In many critical applications it is imperative that the prime power system operate without fail. As a result, specifying engineers may require two on-site power generation plants to insure that an alternate power source will be available. In this scenario the Communication Towers Shelters Dual Prime Source option is ideally suited.
Dual prime operation is typically utilized for installations where no utility power is available thereby requiring two generator sources to supply a site load. This option allows either source to be selected as the “preferred” or “prime” source. The preferred selected generator would be operating on load, with the alternate “standby” generator stopped.
When the “preferred” generator source fails, the transfer switch will automatically transfer to the alternate generator supply if available.
As in a conventional transfer switch, the Dual Prime Source Transfer Switch is designed to transfer a load between two power sources with one power source being designated as the Preferred Source (Genset No.1) while the other is designated as the Alternate Source (Genset No.2).
In this system, selection of the Preferred Source (Genset No.1 or Genset No.2) is accomplished by a door mounted selector switch provided. In the Automatic mode, a time clock alternates which power source is the Preferred Source at a set time or multiple times during a seven day period.
If a failure of the Preferred Source occurs, the transfer switch will start the Alternate Source and transfer the load to it. When the faulted Preferred Source is returned to service, the transfer switch will then retransfer the load back to the Preferred Source power.
The Dual Prime Source accessory for a Generator to Generator system provides the following accessories and/or descriptions:
CYCLIC OPERATION ATS – PLC or Analog Approach (Contactor or Breaker Type)
a. 1 or 3 phase close differential over/undervoltage sensing on both sources
b. Time Delay Control timer for both sources to allow engine to attain speed
c. Engine Maintain Timer for both sources to allow engine cool down period
d. Preferred Source Selector switch to choose the preferred (Genset No.1 – Auto -
Genset No.2) source with “OFF” option
e. Pilot lights to indicate the source to which the load is connected and FAULTS
f. Fault RESET button and TEST button for LAMPS (Busted)
g. A fourteen day or preferred time clock which will automatically alternate the
generator set selected as the Preferred Source at a chosen interval to ensure even
running time on both engine generator sets. (Automatic operation only)
h. ATS & Generator Remote Controlling, Monitoring and Communication Capability
1. TCP/IP over Ethernet Connectivity
2. Supports SNMP v1, SNMP v2 Protocols
3. Alarm and Status functions
Normal operation would require one generator continuously on load with the second generator operating as a “standby” unit.
Dual prime logic allows an operator to select which source is “preferred” (i.e. either source may be selected as preferred or Automatic Mode), therefore, the opposite source will act as the “standby” source.
A PREFERRED SOURCE selector switch is provided for an operator to manually select a “Preferred” operating source. The “Preferred” selected source will continuously operate on load with an engine start signal maintained. The non-selected unit (standby) will remain in the OFF condition. The “standby” unit will be signaled to automatically start the engine and transfer on load (following its engine start and warm-up delay period) should the “Preferred” operating unit fail. When the “Preferred” selected unit is returned to normal operating status, the load will automatically retransfer back to the “Preferred” selected source.
If the PREFERRED SOURCE selector switch is turned to the non-operating unit, the load will automatically transfer to this new “Preferred” source once the engine has started and warm-up period has expired. The originally selected prime unit will continue to operate for its cooldown period (0-1800 sec. adjustable), and then stop.
Note: For automatic operation, both engine control panels must be set for the automatic mode of operation.
When the selected sources supply voltage drops below a preset nominal value (70 -
100% of rated adjustable) on any phase, an engine start delay circuit will be initiated to the opposite (standby) sources engine control and the transfer to the sleeted source signal will be removed (i.e. contact opening). Following expiry of the engine start delay period (0-60 sec. adjustable) an engine start signal (contact closure) will be given. Once the opposite (or standby) engine starts, the transfer switch controller will monitor the generator’s voltage and frequency levels. Once the generator voltage and frequency rises above preset values (70 - 100% nominal adjustable), the engine warm-up timer will be initiated. Once the warm-up timer expires (0-1800 sec. adjustable), the transfer signal (contact closure) will be given to the transfer switch mechanism. The load will then transfer from the prime selected source to the opposite (standby) source via motor driven mechanism.
The “standby” will continue to supply the load until the prime selected source has returned and the retransfer sequence is completed as follows:
When the prime selected source voltage is restored to above the preset values (70 - 100% of rated adjustable) on all phases, then the load will retransfer from the “standby” source back to the prime source.
An engine cooldown timer circuit will be initiated once the load is transferred from the “standby” generator. Following expiry of the cooldown delay period (0-30 min. adjustable), the engine start signal will be removed (contact opening) to initiate stopping of the “standby” generator set.
Saturday, June 13, 2009
Procurement / Material Engineer – Electrical
Principal duties of the position include:
- Identification, scheduling and procurement of the project construction materials to meet the requirements of the established program of work and the specifications as defined in the contract.
- Preparation of materials delivery schedules in accordance with the overall and detailed work programs.
- Propose the most suitable sources of supply taking into consideration the combined factors of quality, price, and delivery that are most economical to the project.
- Monitoring receipt, issue, and usage of materials in order to keep stocks at an adequate level and to determine and report on wastage.
- Identification and compilation from contract documents all quantities and specifications of materials required for the project. Studying materials prices as shown in the budget, and recommending substitute materials where in his opinion they would be more advantageous to the project.
- Review the overall and the detailed construction programs, and schedules materials deliveries accordingly to ensure that materials will be available on site as and when required.
- Solicit offers from local and overseas suppliers and negotiates with them in order to obtain the best suitable terms concerning quality, price, and delivery; recommend to the Project Manager / Procurement Manager the most suitable source of supply.
- Discussing with client/consultant and obtaining their acceptance of alternative or substitute materials.
- Placing firm orders with the nominated suppliers, following up on shipments and monitors deliveries to site, expediting with suppliers/forwarders as necessary to meet schedules. Approve invoices for payment against goods duly checked and received.
- Liaise with Managing Office on such materials as are to be ordered by them, confirming specifications, quantities, and delivery schedules.
- Monitoring consumption trends and current stock levels of materials in order to plan future requirements and replenish stocks as necessary. Monitoring materials issues against actual usage in order to determine the waste factor and reports his finding.
- Identification, scheduling and procurement of the project construction materials to meet the requirements of the established program of work and the specifications as defined in the contract.
- Preparation of materials delivery schedules in accordance with the overall and detailed work programs.
- Propose the most suitable sources of supply taking into consideration the combined factors of quality, price, and delivery that are most economical to the project.
- Monitoring receipt, issue, and usage of materials in order to keep stocks at an adequate level and to determine and report on wastage.
- Identification and compilation from contract documents all quantities and specifications of materials required for the project. Studying materials prices as shown in the budget, and recommending substitute materials where in his opinion they would be more advantageous to the project.
- Review the overall and the detailed construction programs, and schedules materials deliveries accordingly to ensure that materials will be available on site as and when required.
- Solicit offers from local and overseas suppliers and negotiates with them in order to obtain the best suitable terms concerning quality, price, and delivery; recommend to the Project Manager / Procurement Manager the most suitable source of supply.
- Discussing with client/consultant and obtaining their acceptance of alternative or substitute materials.
- Placing firm orders with the nominated suppliers, following up on shipments and monitors deliveries to site, expediting with suppliers/forwarders as necessary to meet schedules. Approve invoices for payment against goods duly checked and received.
- Liaise with Managing Office on such materials as are to be ordered by them, confirming specifications, quantities, and delivery schedules.
- Monitoring consumption trends and current stock levels of materials in order to plan future requirements and replenish stocks as necessary. Monitoring materials issues against actual usage in order to determine the waste factor and reports his finding.
Saturday, February 07, 2009
NEC 2008 - UPDATE
Article 100 Please review definitions for:
Bonding, Branch-Circuit Over-current Protection, Clothes Closet
Ground, Grounding, Grounded, Intersystem Bonding
Termination, Kitchen (Key words “an area”), Neutral
Conductor/Neutral Point, Short Circuit Current Ratings
Article 110.16 Revised: Electrical equipment shall be field marked with
“Arc Flash Warning” signs.
Article 110.22 Revised and New: All equipment shall be marked
(B) + (C) “series combination systems” and identified, whether manufactured
as a system or an individually engineered designed systems.
Article 110.26 Revised: Equipment rooms require 2 egress doors when
(C)(2) equipment is rated 1200 amps or more and is over 6 feet wide.
Article 110.26(C)(3) New: Egress Doors in equipment rooms less than 25’
from equipment rated 1200 amp or more require panic/pressure
hardware and the doors are required to open in the direction of the
egress (see 110.33 (A)(B) for over 600V equipment)
Article 200.2 (B) Revised: Continuity of the grounded conductor cannot
rely on metallic enclosures, raceways, or cable armor.
Article 210.4 (B) Revised: All ungrounded conductors of a multi-wire circuit
shall be simultaneously disconnected at the point of origin.
Article 210.4 (D) Revised: All ungrounded and neutral conductors of a multi-wire circuit shall be
grouped together when entering in a panel unless in their own raceway or cable.
(Example of grouping is wire tires).
Article 210.8 Deleted: GFCI Protection is now required for all 120 V 15 and 20
(A)(2) + (A)(5) amp receptacles in garages, accessory building and unfinished basements.
(Exceptions were deleted for appliances, etc.)
Article 210.8 Revised Definition: In other than dwellings, all 15 amp and 20 amp 120V
(B) (2) receptacles require GFCI Protection in kitchens other than dwellings.
(definition of a kitchen)
Article 210.8 Revised Definition: In other than dwellings, all 120 V 15 and 20
(B) (4) amp outdoor receptacles are required GFCI Protection
Article 210.8 New: All 15 amp and 20 amp 120 V receptacles require GFCI
(B) (5) Protection within 6’ of sinks in other than dwellings (see specific exceptions).
Article 210.8 (C) Revised Definition: All receptacles not exceeding 240 V required GFCI Protection
in a dwelling boat hoist.
Article 210.12 (B) Revised Definition: Major change for arc fault protection in dwelling units. All
120V, 15 amp and 20 amp branch circuits. (See specific list of rooms)
Article 210.52 Revised Definition: Switched controlled receptacles are not considered as the
required outlets for dwelling units. (switching one half of the receptacle will still
meet the required outlets).
Article 210.52 (E) New: Balconies, decks and porches that are accessible from inside a dwelling unit
(20 ft 2) or more, require at least 1 receptacle outlet not more than 6 ½’ above the
surface.
Article 210.60 (A) Revised: Sleeping rooms in dormitories shall have the required receptacle outlets
in accordance with 210.52 (A) and (D).
Article 210.62 Revised: Show window receptacles shall be within (18 inches) of the top of the
window.
Article 215.6 Revised: Feeders shall include an equipment grounding conductor
(see 250.32 (B) ) for exceptions for existing buildings.
Article 215.10 Revised: Ground fault protection of equipment when supplied by a
EXCEP. 2 transformer must be on the load side of the transformer and not the primary side
when required by this article.
Article 230.44 Revised: Service conductors when installed in cable trays with
EXCEP. fused wiring requires solid barriers and the cable tray must be identified “service
entrance conductors” in a manner along the entire length of the tray so to be
readily traced.
Article 230.82 (3) Revised: Disconnects ahead of metering equipment is being considered as a
mandatory installation by many power companies, especially on 277/480V
services. This will provide a level of safety for working on metering equipment. In
most cases it appears the disconnect will be owned, installed and maintained by
the power companies. (Check with your local power company for clarification).
Article 230.205 (A) Revised: Service disconnects for primary power shall be permitted to not be
readily accessible.
Article 240.24 (F) New: Prohibits over current devices to be installed over stair steps.
Article 250.30 Revised: Where grounding multiple separately derived systems
(A)(4) to a single grounding electrode conductor, the bonding jumpers must be installed
at the point the grounding taps are connected.
Article 250.32 (B) Revised: An equipment grounding conductor is required to be ran with the feeder
when feeding separate buildings or structures. (See exception)
Article 250.35 Revised: Clarifies generator bonding, grounding and grounded
(A)(B) conductor sizing for separately derived and non separately derived systems (See
250.30 for separately derived); (See 250.102 (C)) for supply side of non
separately derived systems and 250.102 (D) for load side of non separately
derived systems) (Example of a separately derived system is : when the grounded
conductor of the system is broken and not solid by a transfer switch)
Article 250.52 Revised: Concrete encased electrodes can be located vertically
(A)(3) when within the portion of the footer or foundation connected to earth (See other
requirements of this article)
Article 250.64 (D) Revised: Clarifies grounding requirements when services consist of multiple
disconnects (1) tapping a single grounding electrode conductors sized for the
total service and each tap size for the individual disconnect by 250.66.
(2) Installing individual grounding electrode conductors sized for each individual
disconnect by 250.66. (3) Installing a single grounded electrode conductor to a
common location, in an enclosure.
Article 250.94 Revised: Bonding for other systems such as CATV, communications, etc. shall
have an external means available by installation of listed equipment grounding
bars that will accept at least 3 terminations. These bars shall be bonded with a
minimum #6 AWG copper conductor to the service equipment or the grounding
electrode. (See exceptions for existing installations).
Article 250.104 Revised: Clarifies when metallic water systems are metallically isolated at a
tenant space supplied by a feeder, the equipment grounding conductor ran to an
accessible metallic water system is size by 250.122 for the purpose of bonding
the tenant space sub panel.
Article 250.122 (C) Revised: Clarifies that a single equipment grounding conductor used in
raceways, cables and cable trays for multiple circuits shall be sized for the largest
over-current device by 250.122. (See 392 for other grounding requirements and
sizing for cable trays.)
Article 250.146 (A) Revised: Clarifies that surface mounted box covers may be listed for grounding
when a receptacle is mounted to the cover by a permanent means or locking
screws with flat type surface cover mounting holes (key words listed for
grounding)
Article 300.4 (E) New: Cables and raceways installed under metal corrugated roof decking shall
not be less then 1 ½” from the surface.
Article 300.5(B) Revised: Clarifies that the interior in all raceways and enclosures underground
are wet locations. (This includes PVC and conductors and splices installed shall
be rated for wet locations.) (See 300.9 for above grade wet locations)
Article 300.5 Revised: Clarifies underground conductors and cable under
(C) + (C1) a building shall be in a raceway.
Article 300.5 Revised: Clarifies direct buried cables and conductors emerging
(D) (1) from grade shall be protected to at least 8’ above finish grade to at least 18”
below grade
Article 300.9 New: Insulated conductors in raceways, in wet locations above grade, shall be
listed for wet locations. (Example: NMB installed in PVC outside to feed an a/c
disconnect would be a violation) (Damp locations would also apply to this
requirement when condensation and moisture occur).
Article 300.12 New: Cables and conduits when installed in open bottom type
(EXCP 2) equipment are not required to be mechanically secured to the enclosures.
(Bonding of metal raceways and cables is a required)
Article 310.15 New: Conductors and cables installed in raceways exposed to
(B) (2) (C) direct sunlight on roofs will follow the adjustments shown in Table 310.15 (B) (2)
for ambient temperatures. (Please take note.)
Article 314.16 Revised: Devices or utilization equipment wider than a single
(B) (4) box shall have a double volume allowanced for each gang required by Table
314.16 (a). (Example given: is an electric dryer outlet in a single gang box will not
allow proper box fill space for the conductors and device)
Article 314.28 Revised: Clarifies that this article is to include boxes with
(A)(2) splices as well as Angle and U pulls, to be sized by this article.
Article 334.12 Revised: NM cable is not permitted in Type I and Type 2
(EXCEP.) construction; (basically block and steel construction types). It is now permissible
if installed in a raceway, not a partial sleeve, and meets all other installation
codes. (Interior installation of S.E. and S.E.R. cables also apply to Part II of this
Article. Also see 338.10(B)(4).)
Article 334.12 Revised: Clarifies NM shall not be installed in a wet and damp
(B)(4) location. (Keep in mind, NM installed in PVC or Metallic raceways does not
change the location classification.)
Article 334.15 (C) Revised: When sleeving NM on the wall in a basement or crawl space thru
conduit or tubing, the cable must be secured within 12” of where it enters the
tubing or conduit. Insulated bushing or adapters are also a requirement for
abrasion. (See this entire article for other requirements)
Article 334.80 Revised: Clarifies that the ampacity of NM cable shall be adjusted by 310.15
(B)(2)(a) if affected when installed in contact with thermal insulation without
maintaining cable spacing. (See the manufactures test reports for effects)
Article 338.12 (A) Revised: Clarifies S.E. cable shall not be used underground with or without a
raceway (See 338.12 (A)&(B) for article restructure).
Article 342.30 (C) New: IMC not over 18” does not require support when installed without
coupling and is terminated without encountering oversized, concentric or
eccentric knockouts. (Same rule applies for RMC., see344.30 (C) and PVC,
352.30 (C).)
Article 348.12 (1 Revised: FMC shall not be permitted in wet locations.
Article 348.60 Revised: Clarifies FMC where installed for flexibility requires the installation of an
equipment grounding conductor. (See 350.60, the same requirement applies for
LFMC)
Article 350.30 (A) Revised: Revised and restructured for securing LFMC when fished or installed for
flexibility. (See article, goes by trade sizes)
Article 352.10 (F) Revised: Revised and new F.P.N. added to clarify that schedule 80 is identified
for areas subject to physical damage.
Article 362.30 New: ENT shall be permitted to be fished in unbroken lengths
(EXCEP 3) without couplins.
Article 366.2 Revised: Revised definitions for metallic and non-metallic gutters. Distinguishes
that gutters and wireways are not the same. (See articles 376 and 378 for
wireways.)
Article 376.56 Revised: Clarifies that distribution blocks that serve live parts in a
(B) (4) wireway shall be of the insulated type. (Wireway covers do not provide
compliance.)
Article 404.8 (C) New: General use multiple snap switches that are supplied by more than 1 circuit
must be listed and marked as a 2 or 3 circuit switch, or rated for the system line to
line voltage.
Article 406.4 (G) New: Receptacles when grouped or ganged in a enclosure with other devices
must be arranged so the voltage between all adjacent devices does not exceed
300V unless an approved and identified barrier is installed between the devices
(Now mirrors existing snap switch requirements in 404.8 (B).
Article 406.8 Revised: Standard non-locking straight blade receptacles rated 15 and 20 A;
(A) (B) & (Excep.) 125V and 250V installed outdoors in a damp location or in any wet location shall
be a listed weather resistant type. Exception: high pressure spray areas shall be
permitted to have weather proof enclosures that remain weather proof after the
attachment plug is removed.
Article 406.11 New: Tamper-Resistant Receptacles are now required in all locations in dwelling
units listed in 210-52 (This will also apply to retrofits and repairs)
Article 408.3 (F) New: Switchboards and panel boards supplied by 4 wire delta high leg system,
must be permanently field marked to warn users of voltage supply. (See specific
wording as to how to mark the system. Example of a high leg system voltage is
120/240v 3 phase with a high leg of 208v.)
Article 408.4 Revised: Panel board circuit directories have been required to be specifically
labeled to identify what each circuit breaker feeds, now spare breaker spaces with
a breaker installed shall also be identified as a spare position. (Both rules apply to
service/panel changes as well as new installations.)
Article 408.36 Revised: Panel boards require over-current protection on the supply side (See
exceptions 1, 2, and 3). The differentiation between a lighting and appliance
panel board and a power panel board has been removed. The limitation of 42
overcurrent devices in a panel board has been revised to be permitted unless
prohibited by the panel boards “listing” or by exception 2. (My interpretation is that
transformers and feeders in the 10’ tap rule will also require a main.)
Article 409 Revised: Industrial Control Panels: This article should be reviewed in its entirety
especially 409.106 and 409.110 for “listing” information that is required to be
marked on equipment.
Article 410.16 Revised: LED luminaries were included in the article requirements for clothes
(A) (3) closets (must be listed for the use)
Article 410.130 Revised: Listed internal or external disconnects are required for
(G1, 2, 3) indoor, other then residential fluorescent luminaries, that utilize double ended
lamps and contain ballast for servicing. If supplied by a multi-wire branch circuit
then all conductors including the grounded conductor shall be disconnected. A
single switch is permissible to disconnect more than one fixture when the switch is
accessible, within sight of the fixture, the fixtures are not supplied by a mulitwire
circuit and the area will not be left in total darkness. (This will apply to old and new
installations).
Article 422.51 Revised: Clarifies the GFCI protection requirements for vending machines
manufactured or remanufactured prior to January 1, 2005.
Article 422.52 New: Electric drinking fountains now require GFCI protection.
Article 424.19 Revised: Disconnecting means for fixed electric space heating equipment shall
have an ampere rating not less than 125% of the total load of the motors and
heaters. Disconnect locking devices shall remain in place whether or not the lock
is installed.
Article 430.103 Revised: Motor and controller disconnecting means are not permitted to be a
type that will close automatically. (Example given is a time clock). While manually
switched off, could automatically return to the on position while servicing the unit.
Article 440.14 Revised: A/C and refrigeration disconnects shall not be mounted on equipment
access panels or to obstruct the visibility of the equipment nameplate. Disconnect
locking devices shall remain in place with or without the lock installed.
Article 445.19 Revised: Generator disconnects shall be lockable in the open position.
(Important: Article 225.32 and 445.18 also apply to the disconnect location of a
generator.)
Article 480.5 New: On over 30V storage battery systems a disconnecting means shall be
readily accessible and within sight from the system; in order to disconnect the
derived ungrounded conductors.
Article 501.30(B) Revised: Flexible and liquid tight metal conduit shall not be used as the sole
grounding means path (also see 502.30 (B) and 503.30 (B) for same requirement)
Article 511.20 New: Definitions added to define a major and minor repair garage (see article for
all revisions.) (May require an engineer evaluation for a minor repair
classification.)
Article 525.11 Revised: Where multiple sources of supply serve portable structures in carnivals,
etc. and are not separated by less than 12’, the equipment grounding conductors
must be bonded together by 250.122 but not smaller than 6 awg. (see new
definitions added in this article)
Article 547.5 (F) Revised: Agricultural Buildings: Equipment grounding conductors shall be copper
and if installed underground it shall be insulated or covered.
Article 547.5 (G) Revised: Accessible receptacles supplying dedicated loads are not required
GFCI protection when a GFCI receptacle is installed within 3 feet, of the non-
GFCI receptacle.
Article 547.9 (E) New: When more than 1 service is installed less than 500’ apart, a plaque shall
be installed at the distribution points donating the locations of the other
distribution points.
Article 555.9 Revised: Conductor splicing devices listed for submersion on floating piers can
be used above the water line and below the datum plane in junction boxes.
Article 555.21 Revised: Class I, Division I & II areas; total revision (should be read)
Article 600.6 Revised: When sign and controller disconnects are not within sight
(A) (1) of the sign, a disconnect locking means that is the type remains in
place shall be permitted.
Article 600.21 (E) Revised: Attic and soffits that ballast, transformers and power
supplies are installed, require a light containing a switch or a wall
switch at the point of entry. The light shall be located at the
equipment.
Article 680.12 Revised: Clarifies maintenance disconnects must be readily accessible and 5’
from the inside walls of a pool, spa, or hot tub unless separated by a barrier
that provides a 5’ reach path (integral hot tub disconnect are not
recognized)
Article 680.22 Revised: Several articles for receptacle distances have been
changed to be located at least 6’ from the inside walls of a pool.
See 680.22 (A)(1), (2),(3) ; 680.34,680.43 (A), 680.43 (A)(1), 680.62
(E), 680.71.
Article 680.22 (B) Revised: Hard wired and cord connected pool pumps are required
to be GFCI protected. Applies to 15A and 20A, 120V or 240V.
Article 680.22 (E) Revised: Receptacle outlets not associated with a indoor pool shall
be at least 10’ from the inside walls of the pool.
Article 680.26 Revised: Equipotenial bonding requirements have had a major
revision. Please review in its entirety: short cut to some of the
changes are as follow:
1. All surfaces paved and unpaved are now included in the 3’ equipotential
plane distance.
Types of Grids
A. Structural reinforcement steel includes conductive type rebar and wire
mesh when used in concrete are recognized as that portion of the grid.
B. A single 8AWG bare solid copper conductor following the
contour of the pool. This conductor shall be installed 18” to
24” from the inside walls of the pool and at a minimum depth
of 4” and maximum depth of 6” below subgrade.
C. Copper grid construction in 12” by 12” network.
Note: (1) Conductive Rebar and wire mesh are only acceptable when
used only in a concrete pour. (2) Outside of a poured area an 8 AWG
copper conductor or grid network as described in B will only be acceptable.
(3) Deck bond shall be connected to the pool in 4 uniformed spaced
locations.
Article 680.26 (C) New: An intentional bond of a minimum conductive surface area of 5806 mm2
(9 in.2) shall be installed in contact with the pool water and it must be connected
to the equipotential bonding grid. (This would apply to pool water that is not in
contact with a (9 in2) conductive surface.)
Article 680.31 Revised: Storable Pool pumps are required to have integral GFCI
protection built into the supply cord within 12” of the attachment plug.
Article 680.71 Revised: Hydromassage tubs and their associated equipment are required to be
on an individual branch circuit.
Article 680.74 Revised: Clarifies that other metal piping for a hydromassage tub
shall not be required to be attached to any panel boards or
electrodes but connected to a terminal on the circulating pump.
Article 695.6 Revised: Fire pump supply conductors when protected by fire rated assemblies
or listed electrical protective circuit systems shall now have a 2 hr rating or be
encased in concrete.
Bonding, Branch-Circuit Over-current Protection, Clothes Closet
Ground, Grounding, Grounded, Intersystem Bonding
Termination, Kitchen (Key words “an area”), Neutral
Conductor/Neutral Point, Short Circuit Current Ratings
Article 110.16 Revised: Electrical equipment shall be field marked with
“Arc Flash Warning” signs.
Article 110.22 Revised and New: All equipment shall be marked
(B) + (C) “series combination systems” and identified, whether manufactured
as a system or an individually engineered designed systems.
Article 110.26 Revised: Equipment rooms require 2 egress doors when
(C)(2) equipment is rated 1200 amps or more and is over 6 feet wide.
Article 110.26(C)(3) New: Egress Doors in equipment rooms less than 25’
from equipment rated 1200 amp or more require panic/pressure
hardware and the doors are required to open in the direction of the
egress (see 110.33 (A)(B) for over 600V equipment)
Article 200.2 (B) Revised: Continuity of the grounded conductor cannot
rely on metallic enclosures, raceways, or cable armor.
Article 210.4 (B) Revised: All ungrounded conductors of a multi-wire circuit
shall be simultaneously disconnected at the point of origin.
Article 210.4 (D) Revised: All ungrounded and neutral conductors of a multi-wire circuit shall be
grouped together when entering in a panel unless in their own raceway or cable.
(Example of grouping is wire tires).
Article 210.8 Deleted: GFCI Protection is now required for all 120 V 15 and 20
(A)(2) + (A)(5) amp receptacles in garages, accessory building and unfinished basements.
(Exceptions were deleted for appliances, etc.)
Article 210.8 Revised Definition: In other than dwellings, all 15 amp and 20 amp 120V
(B) (2) receptacles require GFCI Protection in kitchens other than dwellings.
(definition of a kitchen)
Article 210.8 Revised Definition: In other than dwellings, all 120 V 15 and 20
(B) (4) amp outdoor receptacles are required GFCI Protection
Article 210.8 New: All 15 amp and 20 amp 120 V receptacles require GFCI
(B) (5) Protection within 6’ of sinks in other than dwellings (see specific exceptions).
Article 210.8 (C) Revised Definition: All receptacles not exceeding 240 V required GFCI Protection
in a dwelling boat hoist.
Article 210.12 (B) Revised Definition: Major change for arc fault protection in dwelling units. All
120V, 15 amp and 20 amp branch circuits. (See specific list of rooms)
Article 210.52 Revised Definition: Switched controlled receptacles are not considered as the
required outlets for dwelling units. (switching one half of the receptacle will still
meet the required outlets).
Article 210.52 (E) New: Balconies, decks and porches that are accessible from inside a dwelling unit
(20 ft 2) or more, require at least 1 receptacle outlet not more than 6 ½’ above the
surface.
Article 210.60 (A) Revised: Sleeping rooms in dormitories shall have the required receptacle outlets
in accordance with 210.52 (A) and (D).
Article 210.62 Revised: Show window receptacles shall be within (18 inches) of the top of the
window.
Article 215.6 Revised: Feeders shall include an equipment grounding conductor
(see 250.32 (B) ) for exceptions for existing buildings.
Article 215.10 Revised: Ground fault protection of equipment when supplied by a
EXCEP. 2 transformer must be on the load side of the transformer and not the primary side
when required by this article.
Article 230.44 Revised: Service conductors when installed in cable trays with
EXCEP. fused wiring requires solid barriers and the cable tray must be identified “service
entrance conductors” in a manner along the entire length of the tray so to be
readily traced.
Article 230.82 (3) Revised: Disconnects ahead of metering equipment is being considered as a
mandatory installation by many power companies, especially on 277/480V
services. This will provide a level of safety for working on metering equipment. In
most cases it appears the disconnect will be owned, installed and maintained by
the power companies. (Check with your local power company for clarification).
Article 230.205 (A) Revised: Service disconnects for primary power shall be permitted to not be
readily accessible.
Article 240.24 (F) New: Prohibits over current devices to be installed over stair steps.
Article 250.30 Revised: Where grounding multiple separately derived systems
(A)(4) to a single grounding electrode conductor, the bonding jumpers must be installed
at the point the grounding taps are connected.
Article 250.32 (B) Revised: An equipment grounding conductor is required to be ran with the feeder
when feeding separate buildings or structures. (See exception)
Article 250.35 Revised: Clarifies generator bonding, grounding and grounded
(A)(B) conductor sizing for separately derived and non separately derived systems (See
250.30 for separately derived); (See 250.102 (C)) for supply side of non
separately derived systems and 250.102 (D) for load side of non separately
derived systems) (Example of a separately derived system is : when the grounded
conductor of the system is broken and not solid by a transfer switch)
Article 250.52 Revised: Concrete encased electrodes can be located vertically
(A)(3) when within the portion of the footer or foundation connected to earth (See other
requirements of this article)
Article 250.64 (D) Revised: Clarifies grounding requirements when services consist of multiple
disconnects (1) tapping a single grounding electrode conductors sized for the
total service and each tap size for the individual disconnect by 250.66.
(2) Installing individual grounding electrode conductors sized for each individual
disconnect by 250.66. (3) Installing a single grounded electrode conductor to a
common location, in an enclosure.
Article 250.94 Revised: Bonding for other systems such as CATV, communications, etc. shall
have an external means available by installation of listed equipment grounding
bars that will accept at least 3 terminations. These bars shall be bonded with a
minimum #6 AWG copper conductor to the service equipment or the grounding
electrode. (See exceptions for existing installations).
Article 250.104 Revised: Clarifies when metallic water systems are metallically isolated at a
tenant space supplied by a feeder, the equipment grounding conductor ran to an
accessible metallic water system is size by 250.122 for the purpose of bonding
the tenant space sub panel.
Article 250.122 (C) Revised: Clarifies that a single equipment grounding conductor used in
raceways, cables and cable trays for multiple circuits shall be sized for the largest
over-current device by 250.122. (See 392 for other grounding requirements and
sizing for cable trays.)
Article 250.146 (A) Revised: Clarifies that surface mounted box covers may be listed for grounding
when a receptacle is mounted to the cover by a permanent means or locking
screws with flat type surface cover mounting holes (key words listed for
grounding)
Article 300.4 (E) New: Cables and raceways installed under metal corrugated roof decking shall
not be less then 1 ½” from the surface.
Article 300.5(B) Revised: Clarifies that the interior in all raceways and enclosures underground
are wet locations. (This includes PVC and conductors and splices installed shall
be rated for wet locations.) (See 300.9 for above grade wet locations)
Article 300.5 Revised: Clarifies underground conductors and cable under
(C) + (C1) a building shall be in a raceway.
Article 300.5 Revised: Clarifies direct buried cables and conductors emerging
(D) (1) from grade shall be protected to at least 8’ above finish grade to at least 18”
below grade
Article 300.9 New: Insulated conductors in raceways, in wet locations above grade, shall be
listed for wet locations. (Example: NMB installed in PVC outside to feed an a/c
disconnect would be a violation) (Damp locations would also apply to this
requirement when condensation and moisture occur).
Article 300.12 New: Cables and conduits when installed in open bottom type
(EXCP 2) equipment are not required to be mechanically secured to the enclosures.
(Bonding of metal raceways and cables is a required)
Article 310.15 New: Conductors and cables installed in raceways exposed to
(B) (2) (C) direct sunlight on roofs will follow the adjustments shown in Table 310.15 (B) (2)
for ambient temperatures. (Please take note.)
Article 314.16 Revised: Devices or utilization equipment wider than a single
(B) (4) box shall have a double volume allowanced for each gang required by Table
314.16 (a). (Example given: is an electric dryer outlet in a single gang box will not
allow proper box fill space for the conductors and device)
Article 314.28 Revised: Clarifies that this article is to include boxes with
(A)(2) splices as well as Angle and U pulls, to be sized by this article.
Article 334.12 Revised: NM cable is not permitted in Type I and Type 2
(EXCEP.) construction; (basically block and steel construction types). It is now permissible
if installed in a raceway, not a partial sleeve, and meets all other installation
codes. (Interior installation of S.E. and S.E.R. cables also apply to Part II of this
Article. Also see 338.10(B)(4).)
Article 334.12 Revised: Clarifies NM shall not be installed in a wet and damp
(B)(4) location. (Keep in mind, NM installed in PVC or Metallic raceways does not
change the location classification.)
Article 334.15 (C) Revised: When sleeving NM on the wall in a basement or crawl space thru
conduit or tubing, the cable must be secured within 12” of where it enters the
tubing or conduit. Insulated bushing or adapters are also a requirement for
abrasion. (See this entire article for other requirements)
Article 334.80 Revised: Clarifies that the ampacity of NM cable shall be adjusted by 310.15
(B)(2)(a) if affected when installed in contact with thermal insulation without
maintaining cable spacing. (See the manufactures test reports for effects)
Article 338.12 (A) Revised: Clarifies S.E. cable shall not be used underground with or without a
raceway (See 338.12 (A)&(B) for article restructure).
Article 342.30 (C) New: IMC not over 18” does not require support when installed without
coupling and is terminated without encountering oversized, concentric or
eccentric knockouts. (Same rule applies for RMC., see344.30 (C) and PVC,
352.30 (C).)
Article 348.12 (1 Revised: FMC shall not be permitted in wet locations.
Article 348.60 Revised: Clarifies FMC where installed for flexibility requires the installation of an
equipment grounding conductor. (See 350.60, the same requirement applies for
LFMC)
Article 350.30 (A) Revised: Revised and restructured for securing LFMC when fished or installed for
flexibility. (See article, goes by trade sizes)
Article 352.10 (F) Revised: Revised and new F.P.N. added to clarify that schedule 80 is identified
for areas subject to physical damage.
Article 362.30 New: ENT shall be permitted to be fished in unbroken lengths
(EXCEP 3) without couplins.
Article 366.2 Revised: Revised definitions for metallic and non-metallic gutters. Distinguishes
that gutters and wireways are not the same. (See articles 376 and 378 for
wireways.)
Article 376.56 Revised: Clarifies that distribution blocks that serve live parts in a
(B) (4) wireway shall be of the insulated type. (Wireway covers do not provide
compliance.)
Article 404.8 (C) New: General use multiple snap switches that are supplied by more than 1 circuit
must be listed and marked as a 2 or 3 circuit switch, or rated for the system line to
line voltage.
Article 406.4 (G) New: Receptacles when grouped or ganged in a enclosure with other devices
must be arranged so the voltage between all adjacent devices does not exceed
300V unless an approved and identified barrier is installed between the devices
(Now mirrors existing snap switch requirements in 404.8 (B).
Article 406.8 Revised: Standard non-locking straight blade receptacles rated 15 and 20 A;
(A) (B) & (Excep.) 125V and 250V installed outdoors in a damp location or in any wet location shall
be a listed weather resistant type. Exception: high pressure spray areas shall be
permitted to have weather proof enclosures that remain weather proof after the
attachment plug is removed.
Article 406.11 New: Tamper-Resistant Receptacles are now required in all locations in dwelling
units listed in 210-52 (This will also apply to retrofits and repairs)
Article 408.3 (F) New: Switchboards and panel boards supplied by 4 wire delta high leg system,
must be permanently field marked to warn users of voltage supply. (See specific
wording as to how to mark the system. Example of a high leg system voltage is
120/240v 3 phase with a high leg of 208v.)
Article 408.4 Revised: Panel board circuit directories have been required to be specifically
labeled to identify what each circuit breaker feeds, now spare breaker spaces with
a breaker installed shall also be identified as a spare position. (Both rules apply to
service/panel changes as well as new installations.)
Article 408.36 Revised: Panel boards require over-current protection on the supply side (See
exceptions 1, 2, and 3). The differentiation between a lighting and appliance
panel board and a power panel board has been removed. The limitation of 42
overcurrent devices in a panel board has been revised to be permitted unless
prohibited by the panel boards “listing” or by exception 2. (My interpretation is that
transformers and feeders in the 10’ tap rule will also require a main.)
Article 409 Revised: Industrial Control Panels: This article should be reviewed in its entirety
especially 409.106 and 409.110 for “listing” information that is required to be
marked on equipment.
Article 410.16 Revised: LED luminaries were included in the article requirements for clothes
(A) (3) closets (must be listed for the use)
Article 410.130 Revised: Listed internal or external disconnects are required for
(G1, 2, 3) indoor, other then residential fluorescent luminaries, that utilize double ended
lamps and contain ballast for servicing. If supplied by a multi-wire branch circuit
then all conductors including the grounded conductor shall be disconnected. A
single switch is permissible to disconnect more than one fixture when the switch is
accessible, within sight of the fixture, the fixtures are not supplied by a mulitwire
circuit and the area will not be left in total darkness. (This will apply to old and new
installations).
Article 422.51 Revised: Clarifies the GFCI protection requirements for vending machines
manufactured or remanufactured prior to January 1, 2005.
Article 422.52 New: Electric drinking fountains now require GFCI protection.
Article 424.19 Revised: Disconnecting means for fixed electric space heating equipment shall
have an ampere rating not less than 125% of the total load of the motors and
heaters. Disconnect locking devices shall remain in place whether or not the lock
is installed.
Article 430.103 Revised: Motor and controller disconnecting means are not permitted to be a
type that will close automatically. (Example given is a time clock). While manually
switched off, could automatically return to the on position while servicing the unit.
Article 440.14 Revised: A/C and refrigeration disconnects shall not be mounted on equipment
access panels or to obstruct the visibility of the equipment nameplate. Disconnect
locking devices shall remain in place with or without the lock installed.
Article 445.19 Revised: Generator disconnects shall be lockable in the open position.
(Important: Article 225.32 and 445.18 also apply to the disconnect location of a
generator.)
Article 480.5 New: On over 30V storage battery systems a disconnecting means shall be
readily accessible and within sight from the system; in order to disconnect the
derived ungrounded conductors.
Article 501.30(B) Revised: Flexible and liquid tight metal conduit shall not be used as the sole
grounding means path (also see 502.30 (B) and 503.30 (B) for same requirement)
Article 511.20 New: Definitions added to define a major and minor repair garage (see article for
all revisions.) (May require an engineer evaluation for a minor repair
classification.)
Article 525.11 Revised: Where multiple sources of supply serve portable structures in carnivals,
etc. and are not separated by less than 12’, the equipment grounding conductors
must be bonded together by 250.122 but not smaller than 6 awg. (see new
definitions added in this article)
Article 547.5 (F) Revised: Agricultural Buildings: Equipment grounding conductors shall be copper
and if installed underground it shall be insulated or covered.
Article 547.5 (G) Revised: Accessible receptacles supplying dedicated loads are not required
GFCI protection when a GFCI receptacle is installed within 3 feet, of the non-
GFCI receptacle.
Article 547.9 (E) New: When more than 1 service is installed less than 500’ apart, a plaque shall
be installed at the distribution points donating the locations of the other
distribution points.
Article 555.9 Revised: Conductor splicing devices listed for submersion on floating piers can
be used above the water line and below the datum plane in junction boxes.
Article 555.21 Revised: Class I, Division I & II areas; total revision (should be read)
Article 600.6 Revised: When sign and controller disconnects are not within sight
(A) (1) of the sign, a disconnect locking means that is the type remains in
place shall be permitted.
Article 600.21 (E) Revised: Attic and soffits that ballast, transformers and power
supplies are installed, require a light containing a switch or a wall
switch at the point of entry. The light shall be located at the
equipment.
Article 680.12 Revised: Clarifies maintenance disconnects must be readily accessible and 5’
from the inside walls of a pool, spa, or hot tub unless separated by a barrier
that provides a 5’ reach path (integral hot tub disconnect are not
recognized)
Article 680.22 Revised: Several articles for receptacle distances have been
changed to be located at least 6’ from the inside walls of a pool.
See 680.22 (A)(1), (2),(3) ; 680.34,680.43 (A), 680.43 (A)(1), 680.62
(E), 680.71.
Article 680.22 (B) Revised: Hard wired and cord connected pool pumps are required
to be GFCI protected. Applies to 15A and 20A, 120V or 240V.
Article 680.22 (E) Revised: Receptacle outlets not associated with a indoor pool shall
be at least 10’ from the inside walls of the pool.
Article 680.26 Revised: Equipotenial bonding requirements have had a major
revision. Please review in its entirety: short cut to some of the
changes are as follow:
1. All surfaces paved and unpaved are now included in the 3’ equipotential
plane distance.
Types of Grids
A. Structural reinforcement steel includes conductive type rebar and wire
mesh when used in concrete are recognized as that portion of the grid.
B. A single 8AWG bare solid copper conductor following the
contour of the pool. This conductor shall be installed 18” to
24” from the inside walls of the pool and at a minimum depth
of 4” and maximum depth of 6” below subgrade.
C. Copper grid construction in 12” by 12” network.
Note: (1) Conductive Rebar and wire mesh are only acceptable when
used only in a concrete pour. (2) Outside of a poured area an 8 AWG
copper conductor or grid network as described in B will only be acceptable.
(3) Deck bond shall be connected to the pool in 4 uniformed spaced
locations.
Article 680.26 (C) New: An intentional bond of a minimum conductive surface area of 5806 mm2
(9 in.2) shall be installed in contact with the pool water and it must be connected
to the equipotential bonding grid. (This would apply to pool water that is not in
contact with a (9 in2) conductive surface.)
Article 680.31 Revised: Storable Pool pumps are required to have integral GFCI
protection built into the supply cord within 12” of the attachment plug.
Article 680.71 Revised: Hydromassage tubs and their associated equipment are required to be
on an individual branch circuit.
Article 680.74 Revised: Clarifies that other metal piping for a hydromassage tub
shall not be required to be attached to any panel boards or
electrodes but connected to a terminal on the circulating pump.
Article 695.6 Revised: Fire pump supply conductors when protected by fire rated assemblies
or listed electrical protective circuit systems shall now have a 2 hr rating or be
encased in concrete.
HOLDING TO ELECTRICAL SPECIFICATIONS
Engineers should maintain their positions on electrical system design, whether for code issues, good design practice- or the owner’s best interest
"Why on earth did you design it that way?"
This is a plaint often heard from the contractor, construction manager, or owner when documents are issued for construction. More often than not, the statement is liberally littered with modifying expletives.
The engineer so challenged, must first decide if the question has a legitimate basis. If so, is it a National Electrical Code (NEC) requirement, good practice, or merely designer preference?
The key is to examine code requirements, how the engineer can maintain a position, and the potential impacts to both the engineer and the project if they fold on their position.
Engineers are charged with a mandate to "safeguard life, health and property, and promote the public welfare," as well as meet project requirements. In addition, there are instances in which they are called upon to certify that drawings to which they have affixed their seals meet all requirements of the NEC and the Authority Having Jurisdiction (AHJ). To meet these weighty obligations engineers must consider seriously their mandate and- on a more practical level- interpret applicable NEC sections for each project and assure that their design meets all requirements.
By stamping and signing design drawings, engineers are signifying that they believe the documents meet project and code. When these documents are sent to contractors for construction bidding, the questions begin. The most common topics of discussion- from contractors, owners and others, comprise the following:
Wire Sizing
• Ampacity. There have been numerous articles written on the subject of conductor sizing to meet the NEC requirements as described in Article 310 (see sidebar, "NEC Conductor Sizing,") These articles agree
The Cast of Characters
Like it or not, there are differing viewpoints on a construction project, and as long as we live in a free market society,there always will be. Participants each have their own agendas and issues of paramount importance. A description of the
cast of character every engineer encounters (and often embodies) follows. While these stereotypes are certainly unfair to many, at the same time there is an underlying truth to the generalizations.
The Owner. The owner wants the best project for either the lowest first cost or life-cycle cost. Meeting code is not always a top priority, particularly when code requirements conflict with project requirements-and when the cost of
compliance increases the budget.
The Construction Manager. Typically hired by the owner, the CM’s views, for the most part, parallel those to the owner.
The AHJ. The Authority Having Jurisdiction (AHJ) wants to project that is safe and meets their interpretation of the various codes. They are usually not interested at all in whether their interpretations impact the cost of the project.
The Contractor. The builder wants to complete the project and make a profit; they’re not necessarily interested in whether the project meets Code, but only that it passes inspection. Also, the contractor be interested in changes to the
design after the contract is signed that mean greater profit for the contractor. So, all opportunities to reduce cost or find design errors can increase the contractor’s profit margin-and his influence with the owner.
The engineer must consider all of these viewpoints, and make value judgments in light of code, cost, constructability, safety and consumer satisfaction (as well as their own profit picture). They must advise the owner on the future operation of the project. Any changes proposed by the contractor must be beneficial to the owner.
That a number of issues must be addressed to properly size conductors, including ambient temperature, termination temperature, number of current-carrying conductors in a raceway, character of the load and type of conductor insulation. While
now included in NEC Appendix B- which is not a code mandate- the Neher-Macgrath calculations for sizing of conductors installed in underground duct banks should also be considered to properly size conductors in a partially insulated environment.
The diligent engineer applies each requirement in the appropriate manner and arrives at a conductor size suitable for the load, the environment and the overcurrent protection. Yet, the controversy often begins when a member of the
construction team compares the conductor sizes on the contract documents to the uncorrected, 75°C column in table 310-16 in the NEC and concludes that the engineer has sized the conductors incorrectly.
The owner or contractor then takes the position that the conductors are too large and, to economize, suggests that the sizes be reduced to match the referenced column.
• Voltage Drop. Ampacities are just one factor in proper conductor sizing. Just as important, though often neglected, is voltage drop. NEC Articles 210-19 (a) (FPN No. 4) and 215-2(b) (FPN No.2)- which are not mandatory rules-recommend sizing both feeders and branch circuits to prevent a voltage drop exceeding 3 percent at the farthest outlet, where the maximum total voltage drop of the feeders and branch circuits does not exceed 5 percent
When the feeder and branch circuit conductors for long circuits are sized on this basis, the conductor sizes are increased even more than that required for ampacity. Perhaps because it is not mandatory, contractors and owners sometimes forget this basic fact. It should not be overlooked, however, because performance and the operating life of utilization equipment can be adversely affected.
Electrical Working Clearance
Clearance for electrical equipment are specified in NEC Articles 110-16 and 384. Working clearances are based on voltage level and conditions of installation, and for installations below 600 volts, these clearances range from 3 to 4 feet in front and in back of equipment (where the equipment has rear access). Headroom is also given as a minimum of 6.5 feet to prevent the installation of electrical equipment in crawlspaces.
Article 384 covers dedicated space in the vicinity of electrical equipment for the installation of conduit and limited physical protection of equipment. Generally speaking, this space is equal to the footprint of the equipment extending from the floor on which the equipment is mounted to the next structural floor, or 25 feet, whichever is less. The article also restricts the intrusion of pipes and ducts into this space.
While the passage clearly states that no equipment foreign to the electrical installation shall be installed in the zones, this often becomes a point of contention between engineer and contractor. In the contractor’s view, the shortest distance between two points is a straight line, even if that line is a pipe passing directly over electrical equipment.
While the code seems clear and straightforward, this is a frequent problem at the construction site. Clearance requirements are often violated to the extent that equipment doors cannot be opened, and Owners and even AHJs may prefer to look the
other way. Many engineering firms have specific coordination stipulations, both in drawings and specifications, to prevent space conflicts between mechanical and electrical systems. In the field, however, there must be a commitment to implement them,
Transformer Protection
Transformer overload and short-circuit protection are addressed in Article 450 of the NEC. Depending on voltage levels and conditions of maintenance and supervision, one of two protection schemes can be used: either primary overcurrent protection
only, or primary and secondary overcurrent protection. Also, the NEC permits fairly wide latitude in the sizing of overcurrent devices.
As a matter of good practice, however, better protection will be realized with breaker settings or fuse ratings lower than the maximum allowable. Likewise, primary-only protection is a minimum-only requirement, which – unlike primary and secondary
protection- does not provide the best protection under all types of fault conditions. Plus, it may introduce nuisance tripping due to magnetizing inrush, cold load pickup and emergency operating conditions.
Using primary and secondary protection, with the primary breaker set between 175 and 200 percent, there is less opportunity for nuisance tripping while offering adequate short-circuit protection for both primary conductors and the transformer. The
secondary overcurrent device, set at 125 percent of full load, provides overload protection. In addition, the primary overcurrent device should be examined to ensure that the transformer damage curve (defined by ANSI/IEEE C57.109) is fully
protected by the primary device, while allowing the transformer magnetizing inrush point to fall below trip characteristics. That way, energizing the transformer will not cause a nuisance trip.
Unfortunately, contractors routinely question the use of larger overcurrent devices and primary conductors on the primary side of the transformer.
Engineers are accused of "overdesigning" projects, overlooking cost savings from reduced conductor and overurrent device sizing. Yet, in most instances, the larger overcurrent device is the same frame size; so, for example, reducing the trip
size from a 200-ampere to a 125-ampere trip on a breaker results in no savings at all. The difference in cost between the conductors and conduit that is perhaps 4 feet long is negligible. In reality, the time wasted in asking the question is
probably more valuable than the cost of the materials needed for the more reliable, better protected installation.
Grounding/Earthing
Conflicts on grounding most often occur between the engineer and the owner’s equipment suppliers. The NEC is very clear. In Article 250-54, it spells out the standard for connecting all grounding conductors to a single grounding electrode.
When electronic systems are installed in a facility, the equipment installation technicians typically request an isolated ground not connected to any other ground in the building, often stating that their equipment will not work without the isolated ground.
The conflict between the NEC requirement and the supplier’s desire is easily resolved: Connect the ground for the electronic system as close to the grounding electrode as possible; this meets the NEC requirement and gives electronic systems their solid, earth ground connection.
The real issue for the systems is having a minimum voltage above ground on the signal ground for the system. By connecting the system ground close to the grounding electrode, there is minimum impedance between the system ground and earth ground,
reducing the voltage to a low value, no matter what the ground current.
An associated but less common request from system technicians is that the voltage difference between neutral and ground at the utilization equipment be less than 1 volt. The equipment ground installed as noted above will minimize the voltage on the
ground; reducing voltage level on the neutral at the utilization equipment is more problematic. Utilization equipment often has a switching power supply, which generates significant harmonic currents that are impressed on to the neutral of the system with a resultant increase in neutral current.
As Ohm’s Law states, when current is increased through the constant circuit impedance, voltage increases. Therefore, the neutral has an inherent voltage impressed at the utilization equipment terminals well above the requirement outside of 1 volt over ground. In fact, no equipment manufacturer has been able to demonstrate either:
1) Good reason for maintaining the neutral-to-ground voltage less than 1 volt; or
2) Any equipment malfunctions attributed to this voltage difference.
Fault Duty
Fault duty on distribution equipment should be a focal point of the engineer’s concentration. Not only is it critical to safety and reliability, but it is an NEC-mandated issue in Article 110-9, which says that equipment intended to break current at fault levels shall have an interrupting rating sufficient for the current that is available at the line terminals.
Contractors, Owners and Construction Managers often seem to think that fault duty of electrical equipment is a myth propagated by engineers to increase the costs of projects. Yet, the fact is that the engineer must meet the NEC requirement by either designing a fully rated system or, as permitted by Underwriters Laboratories (UL), designing a series-rated system. NEC enforces UL requirements in Article 110-3(b), which says that listed or labeled equipment shall be installed and used in accordance with any instructions included in the listing or labeling.
The Contractor that has some passing knowledge of fault duty will suggest that the distribution system be series rated in place of a fully rated system. This suggestion becomes difficult when the series connected rating is applied to systems with a mixture of multiple manufacturers or with various overcurrent devices that are not listed as series connected by UL.
As UL plainly states, "These ratings are applicable only when the series connected devices have been investigated by UL in combination with the end-use equipment and the equipment in which these devices are used is marked with the series connected
rating." Therefore, if series connected devices are not listed in UL Recognized Component directory, they are not suitable for series-rated application.
Between the NEC and UL requirements, engineers very carefully must meet the specific requirements for series ratings confirming in shop drawings equipment labeled for that specific rating- or maintain that all systems must be full-rated.
Resolving Codes and Costs
With all of these viewpoints clouding the issues, the engineer has a difficult problem. Because the engineering firm is hired by the owner, either directly or indirectly, their first commitment must be to the client- the owner.
Along with this commitment, however, engineers must also meet the mandate to protect public safety and welfare. This becomes one of the most sensitive issues engineers face, especially when they choose to hold to a design or specification
against the owner’s wishes. When this happens, these options are available to engineers:
• A Simple Approach: Show the owner where the code does not allow a proposed change. In most cases this is enough
• A Cost-Based Approach: Connect the code-mandated design with construction cost savings or operational savings,
• A Diplomatic Approach: Develop an alternative solution meeting the owner’s requirements and code requirements.
Sometimes, this implies more design time and additional construction cost, but it may be the path of least resistance when owners are adamant about a change.
If these approaches don’t work, further options become less pleasant. Where there appears to be no major hazards, engineers may comply with the owner’s desires and go on record with a letter to the owner stating the engineer’s objection to the approach and recording the reasons why.
For more critical issues, engineers can send a letter absolving themselves of any responsibility- and simply not incorporate the requested approach into the contract documents. This position may risk the loss of future work with the same owner, but this may be a better option than violating a public mandate to design safe buildings.
NEC Conductor Sizing
There are four criteria used for conductor sizing to meet the NEC requirements:
1) The overcurrent device must be sized for the sum of the non-continuous load plus 125 percent of the continuous load.
The overcurrent device may be rounded up to the next available standard size, as long as the device does not exceed 800 amperes.
2) The conductor must be sized so that termination temperatures do not exceed 60°C for conductors smaller than 100 amperes or #1 American wire gauge (AWG), and 75°C for conductors larger than 100 amperes or #1/0 AWG. This results in using the 60°C column of 310-16 for all conductor sizing of circuits 100 amperes and smaller, and the 75°C column of 310-16 for conductors larger than 100 amperes. Even if insulations are utilized, such as XHHW, Z, TFE, etc. two columns must be used to determine conductor sizes.
3) Conductor size and insulation type must take into consideration conditions of use to prevent insulation damage. Conditions of use include more than three current-carrying conductors in a single raceway and high-temperature ambients. High temperature ambients are-according to the heading of the correction-factor chart for 310-16-any ambient conditions that exceed 30°C or 86°F Most electrical rooms and mechanical rooms and mechanical rooms where mechanical rooms where electrical equipment is installed will exceed 86°F under typical operating conditions
Wire sizing and conductor sizing must not only meet code requirements, they must also meet special needs, such as those for partially insulated environments.
4.) The overcurrent device must protect the conductor under all conditions of use.
"Why on earth did you design it that way?"
This is a plaint often heard from the contractor, construction manager, or owner when documents are issued for construction. More often than not, the statement is liberally littered with modifying expletives.
The engineer so challenged, must first decide if the question has a legitimate basis. If so, is it a National Electrical Code (NEC) requirement, good practice, or merely designer preference?
The key is to examine code requirements, how the engineer can maintain a position, and the potential impacts to both the engineer and the project if they fold on their position.
Engineers are charged with a mandate to "safeguard life, health and property, and promote the public welfare," as well as meet project requirements. In addition, there are instances in which they are called upon to certify that drawings to which they have affixed their seals meet all requirements of the NEC and the Authority Having Jurisdiction (AHJ). To meet these weighty obligations engineers must consider seriously their mandate and- on a more practical level- interpret applicable NEC sections for each project and assure that their design meets all requirements.
By stamping and signing design drawings, engineers are signifying that they believe the documents meet project and code. When these documents are sent to contractors for construction bidding, the questions begin. The most common topics of discussion- from contractors, owners and others, comprise the following:
Wire Sizing
• Ampacity. There have been numerous articles written on the subject of conductor sizing to meet the NEC requirements as described in Article 310 (see sidebar, "NEC Conductor Sizing,") These articles agree
The Cast of Characters
Like it or not, there are differing viewpoints on a construction project, and as long as we live in a free market society,there always will be. Participants each have their own agendas and issues of paramount importance. A description of the
cast of character every engineer encounters (and often embodies) follows. While these stereotypes are certainly unfair to many, at the same time there is an underlying truth to the generalizations.
The Owner. The owner wants the best project for either the lowest first cost or life-cycle cost. Meeting code is not always a top priority, particularly when code requirements conflict with project requirements-and when the cost of
compliance increases the budget.
The Construction Manager. Typically hired by the owner, the CM’s views, for the most part, parallel those to the owner.
The AHJ. The Authority Having Jurisdiction (AHJ) wants to project that is safe and meets their interpretation of the various codes. They are usually not interested at all in whether their interpretations impact the cost of the project.
The Contractor. The builder wants to complete the project and make a profit; they’re not necessarily interested in whether the project meets Code, but only that it passes inspection. Also, the contractor be interested in changes to the
design after the contract is signed that mean greater profit for the contractor. So, all opportunities to reduce cost or find design errors can increase the contractor’s profit margin-and his influence with the owner.
The engineer must consider all of these viewpoints, and make value judgments in light of code, cost, constructability, safety and consumer satisfaction (as well as their own profit picture). They must advise the owner on the future operation of the project. Any changes proposed by the contractor must be beneficial to the owner.
That a number of issues must be addressed to properly size conductors, including ambient temperature, termination temperature, number of current-carrying conductors in a raceway, character of the load and type of conductor insulation. While
now included in NEC Appendix B- which is not a code mandate- the Neher-Macgrath calculations for sizing of conductors installed in underground duct banks should also be considered to properly size conductors in a partially insulated environment.
The diligent engineer applies each requirement in the appropriate manner and arrives at a conductor size suitable for the load, the environment and the overcurrent protection. Yet, the controversy often begins when a member of the
construction team compares the conductor sizes on the contract documents to the uncorrected, 75°C column in table 310-16 in the NEC and concludes that the engineer has sized the conductors incorrectly.
The owner or contractor then takes the position that the conductors are too large and, to economize, suggests that the sizes be reduced to match the referenced column.
• Voltage Drop. Ampacities are just one factor in proper conductor sizing. Just as important, though often neglected, is voltage drop. NEC Articles 210-19 (a) (FPN No. 4) and 215-2(b) (FPN No.2)- which are not mandatory rules-recommend sizing both feeders and branch circuits to prevent a voltage drop exceeding 3 percent at the farthest outlet, where the maximum total voltage drop of the feeders and branch circuits does not exceed 5 percent
When the feeder and branch circuit conductors for long circuits are sized on this basis, the conductor sizes are increased even more than that required for ampacity. Perhaps because it is not mandatory, contractors and owners sometimes forget this basic fact. It should not be overlooked, however, because performance and the operating life of utilization equipment can be adversely affected.
Electrical Working Clearance
Clearance for electrical equipment are specified in NEC Articles 110-16 and 384. Working clearances are based on voltage level and conditions of installation, and for installations below 600 volts, these clearances range from 3 to 4 feet in front and in back of equipment (where the equipment has rear access). Headroom is also given as a minimum of 6.5 feet to prevent the installation of electrical equipment in crawlspaces.
Article 384 covers dedicated space in the vicinity of electrical equipment for the installation of conduit and limited physical protection of equipment. Generally speaking, this space is equal to the footprint of the equipment extending from the floor on which the equipment is mounted to the next structural floor, or 25 feet, whichever is less. The article also restricts the intrusion of pipes and ducts into this space.
While the passage clearly states that no equipment foreign to the electrical installation shall be installed in the zones, this often becomes a point of contention between engineer and contractor. In the contractor’s view, the shortest distance between two points is a straight line, even if that line is a pipe passing directly over electrical equipment.
While the code seems clear and straightforward, this is a frequent problem at the construction site. Clearance requirements are often violated to the extent that equipment doors cannot be opened, and Owners and even AHJs may prefer to look the
other way. Many engineering firms have specific coordination stipulations, both in drawings and specifications, to prevent space conflicts between mechanical and electrical systems. In the field, however, there must be a commitment to implement them,
Transformer Protection
Transformer overload and short-circuit protection are addressed in Article 450 of the NEC. Depending on voltage levels and conditions of maintenance and supervision, one of two protection schemes can be used: either primary overcurrent protection
only, or primary and secondary overcurrent protection. Also, the NEC permits fairly wide latitude in the sizing of overcurrent devices.
As a matter of good practice, however, better protection will be realized with breaker settings or fuse ratings lower than the maximum allowable. Likewise, primary-only protection is a minimum-only requirement, which – unlike primary and secondary
protection- does not provide the best protection under all types of fault conditions. Plus, it may introduce nuisance tripping due to magnetizing inrush, cold load pickup and emergency operating conditions.
Using primary and secondary protection, with the primary breaker set between 175 and 200 percent, there is less opportunity for nuisance tripping while offering adequate short-circuit protection for both primary conductors and the transformer. The
secondary overcurrent device, set at 125 percent of full load, provides overload protection. In addition, the primary overcurrent device should be examined to ensure that the transformer damage curve (defined by ANSI/IEEE C57.109) is fully
protected by the primary device, while allowing the transformer magnetizing inrush point to fall below trip characteristics. That way, energizing the transformer will not cause a nuisance trip.
Unfortunately, contractors routinely question the use of larger overcurrent devices and primary conductors on the primary side of the transformer.
Engineers are accused of "overdesigning" projects, overlooking cost savings from reduced conductor and overurrent device sizing. Yet, in most instances, the larger overcurrent device is the same frame size; so, for example, reducing the trip
size from a 200-ampere to a 125-ampere trip on a breaker results in no savings at all. The difference in cost between the conductors and conduit that is perhaps 4 feet long is negligible. In reality, the time wasted in asking the question is
probably more valuable than the cost of the materials needed for the more reliable, better protected installation.
Grounding/Earthing
Conflicts on grounding most often occur between the engineer and the owner’s equipment suppliers. The NEC is very clear. In Article 250-54, it spells out the standard for connecting all grounding conductors to a single grounding electrode.
When electronic systems are installed in a facility, the equipment installation technicians typically request an isolated ground not connected to any other ground in the building, often stating that their equipment will not work without the isolated ground.
The conflict between the NEC requirement and the supplier’s desire is easily resolved: Connect the ground for the electronic system as close to the grounding electrode as possible; this meets the NEC requirement and gives electronic systems their solid, earth ground connection.
The real issue for the systems is having a minimum voltage above ground on the signal ground for the system. By connecting the system ground close to the grounding electrode, there is minimum impedance between the system ground and earth ground,
reducing the voltage to a low value, no matter what the ground current.
An associated but less common request from system technicians is that the voltage difference between neutral and ground at the utilization equipment be less than 1 volt. The equipment ground installed as noted above will minimize the voltage on the
ground; reducing voltage level on the neutral at the utilization equipment is more problematic. Utilization equipment often has a switching power supply, which generates significant harmonic currents that are impressed on to the neutral of the system with a resultant increase in neutral current.
As Ohm’s Law states, when current is increased through the constant circuit impedance, voltage increases. Therefore, the neutral has an inherent voltage impressed at the utilization equipment terminals well above the requirement outside of 1 volt over ground. In fact, no equipment manufacturer has been able to demonstrate either:
1) Good reason for maintaining the neutral-to-ground voltage less than 1 volt; or
2) Any equipment malfunctions attributed to this voltage difference.
Fault Duty
Fault duty on distribution equipment should be a focal point of the engineer’s concentration. Not only is it critical to safety and reliability, but it is an NEC-mandated issue in Article 110-9, which says that equipment intended to break current at fault levels shall have an interrupting rating sufficient for the current that is available at the line terminals.
Contractors, Owners and Construction Managers often seem to think that fault duty of electrical equipment is a myth propagated by engineers to increase the costs of projects. Yet, the fact is that the engineer must meet the NEC requirement by either designing a fully rated system or, as permitted by Underwriters Laboratories (UL), designing a series-rated system. NEC enforces UL requirements in Article 110-3(b), which says that listed or labeled equipment shall be installed and used in accordance with any instructions included in the listing or labeling.
The Contractor that has some passing knowledge of fault duty will suggest that the distribution system be series rated in place of a fully rated system. This suggestion becomes difficult when the series connected rating is applied to systems with a mixture of multiple manufacturers or with various overcurrent devices that are not listed as series connected by UL.
As UL plainly states, "These ratings are applicable only when the series connected devices have been investigated by UL in combination with the end-use equipment and the equipment in which these devices are used is marked with the series connected
rating." Therefore, if series connected devices are not listed in UL Recognized Component directory, they are not suitable for series-rated application.
Between the NEC and UL requirements, engineers very carefully must meet the specific requirements for series ratings confirming in shop drawings equipment labeled for that specific rating- or maintain that all systems must be full-rated.
Resolving Codes and Costs
With all of these viewpoints clouding the issues, the engineer has a difficult problem. Because the engineering firm is hired by the owner, either directly or indirectly, their first commitment must be to the client- the owner.
Along with this commitment, however, engineers must also meet the mandate to protect public safety and welfare. This becomes one of the most sensitive issues engineers face, especially when they choose to hold to a design or specification
against the owner’s wishes. When this happens, these options are available to engineers:
• A Simple Approach: Show the owner where the code does not allow a proposed change. In most cases this is enough
• A Cost-Based Approach: Connect the code-mandated design with construction cost savings or operational savings,
• A Diplomatic Approach: Develop an alternative solution meeting the owner’s requirements and code requirements.
Sometimes, this implies more design time and additional construction cost, but it may be the path of least resistance when owners are adamant about a change.
If these approaches don’t work, further options become less pleasant. Where there appears to be no major hazards, engineers may comply with the owner’s desires and go on record with a letter to the owner stating the engineer’s objection to the approach and recording the reasons why.
For more critical issues, engineers can send a letter absolving themselves of any responsibility- and simply not incorporate the requested approach into the contract documents. This position may risk the loss of future work with the same owner, but this may be a better option than violating a public mandate to design safe buildings.
NEC Conductor Sizing
There are four criteria used for conductor sizing to meet the NEC requirements:
1) The overcurrent device must be sized for the sum of the non-continuous load plus 125 percent of the continuous load.
The overcurrent device may be rounded up to the next available standard size, as long as the device does not exceed 800 amperes.
2) The conductor must be sized so that termination temperatures do not exceed 60°C for conductors smaller than 100 amperes or #1 American wire gauge (AWG), and 75°C for conductors larger than 100 amperes or #1/0 AWG. This results in using the 60°C column of 310-16 for all conductor sizing of circuits 100 amperes and smaller, and the 75°C column of 310-16 for conductors larger than 100 amperes. Even if insulations are utilized, such as XHHW, Z, TFE, etc. two columns must be used to determine conductor sizes.
3) Conductor size and insulation type must take into consideration conditions of use to prevent insulation damage. Conditions of use include more than three current-carrying conductors in a single raceway and high-temperature ambients. High temperature ambients are-according to the heading of the correction-factor chart for 310-16-any ambient conditions that exceed 30°C or 86°F Most electrical rooms and mechanical rooms and mechanical rooms where mechanical rooms where electrical equipment is installed will exceed 86°F under typical operating conditions
Wire sizing and conductor sizing must not only meet code requirements, they must also meet special needs, such as those for partially insulated environments.
4.) The overcurrent device must protect the conductor under all conditions of use.
Friday, February 06, 2009
PRICE AND COST ANALYSIS
Some form of price or cost analysis should be performed in connection with every procurement action, regardless of whether the organization is a vendor or a subrecipient. The form and degree of analysis, however, are dependent on the particular subcontract or purchase, and the pricing situation. Determination of price
reasonableness through price or cost analysis is required even though the procurement
is source directed by the contracting officer of the sponsoring agency.
In some purchases, price analysis alone will be sufficient; in others, price analysis will be used to corroborate the conclusions arrived at through cost analysis. The form and degree of analysis are dependent on facts surrounding a particular subcontracting or purchasing situation. The scope of price analysis performed and the particular techniques used will depend on whether or not cost analysis is done, as well as on such factors as type of product or service, dollar value, purchase method, and extent of competition.
The words "vendor" and "subcontractor" used herein are interchangeable.
Price Analysis is the process of deciding if the asking price for a product or service is fair and reasonable, without examining the specific cost and profit calculations the manufacturer and/or supplier used in arriving at the price. It is basically a process of comparing the price with known indicators of reasonableness.
When adequate price competition does not exist, some other form of analysis is
required. Some reasons that could affect adequate price competition are: specifications are not definitive, tolerances are restrictive, or production capacity limits those eligible to bid.
Examples of other forms of price analysis information include:
• analysis of previous prices paid
• comparison of vendor's price with the in-house estimate
• comparison of quotations or published price lists from multiple vendors
Cost Analysis is the element -by-element examination of the estimated or actual cost of contract performance to determine the probable cost to the vendor. The goal is to form an opinion on whether the proposed costs are in line with what reasonably economical and efficient performance should cost.
Cost or pricing data, which should be provided by the subcontractor, are the means for conducting cost analysis. Such data provide factual information about the costs that the subcontractor says may be incurred in performing the contract. Cost analysis should be performed in those situations where price analysis does not yield a fair and reasonable price and where cost data are required in accordance with prime contract clauses.
Cost analysis techniques are used to break down a contractor's cost or pricing data so as to verify and evaluate each component. Some of the cost elements examined for
necessity and reasonableness are materials costs, labor costs, equipment and overhead. These costs can be compared with actual costs previously incurred for similar work, the cost or pricing data received from other manufacturer and/or supplier, and independent cost estimate breakdowns.
reasonableness through price or cost analysis is required even though the procurement
is source directed by the contracting officer of the sponsoring agency.
In some purchases, price analysis alone will be sufficient; in others, price analysis will be used to corroborate the conclusions arrived at through cost analysis. The form and degree of analysis are dependent on facts surrounding a particular subcontracting or purchasing situation. The scope of price analysis performed and the particular techniques used will depend on whether or not cost analysis is done, as well as on such factors as type of product or service, dollar value, purchase method, and extent of competition.
The words "vendor" and "subcontractor" used herein are interchangeable.
Price Analysis is the process of deciding if the asking price for a product or service is fair and reasonable, without examining the specific cost and profit calculations the manufacturer and/or supplier used in arriving at the price. It is basically a process of comparing the price with known indicators of reasonableness.
When adequate price competition does not exist, some other form of analysis is
required. Some reasons that could affect adequate price competition are: specifications are not definitive, tolerances are restrictive, or production capacity limits those eligible to bid.
Examples of other forms of price analysis information include:
• analysis of previous prices paid
• comparison of vendor's price with the in-house estimate
• comparison of quotations or published price lists from multiple vendors
Cost Analysis is the element -by-element examination of the estimated or actual cost of contract performance to determine the probable cost to the vendor. The goal is to form an opinion on whether the proposed costs are in line with what reasonably economical and efficient performance should cost.
Cost or pricing data, which should be provided by the subcontractor, are the means for conducting cost analysis. Such data provide factual information about the costs that the subcontractor says may be incurred in performing the contract. Cost analysis should be performed in those situations where price analysis does not yield a fair and reasonable price and where cost data are required in accordance with prime contract clauses.
Cost analysis techniques are used to break down a contractor's cost or pricing data so as to verify and evaluate each component. Some of the cost elements examined for
necessity and reasonableness are materials costs, labor costs, equipment and overhead. These costs can be compared with actual costs previously incurred for similar work, the cost or pricing data received from other manufacturer and/or supplier, and independent cost estimate breakdowns.
Monday, August 18, 2008
Electrical Engineer Job Description
Electrical Engineers design and develop electrical systems and/or components to high specifications, focusing on:
• Economy;
• Safety;
• Reliability;
• Quality;
• Sustainability
They are involved in projects from the concept and detail of the design through to implementation, testing and handover.
Most electrical engineers work in a multi-disciplinary project team, including engineers from other specialisms, as well as architects, marketing and sales staff, manufacturers, technicians and customer service personnel.
Electrical engineers need technical knowledge as well as the ability to project manage and multitask. Additional attributes, such as team leadership skills and commercial awareness, are required as careers progress.
» Typical Work Activities
Many organizations now operate cross-functional teams in which the electrical engineer is involved at every stage of design and development in collaboration with colleagues in other engineering functions, as well as those working in production, research, marketing and after-sales services.
The nature of the role varies according to industry or sector, but the range of activities common to many posts is likely to include the following:
• Identifying customer requirements;
• Designing systems and products;
• Reading design specifications and technical drawings;
• Researching suitable solutions and estimating costs and timescales;
• Making models and prototypes of products;
• Working to BS and EN standards;
• Liaising with others in the design team;
• Liaising with clients and contractors;
• Attending meetings on site;
• Designing and conducting tests;
• Recording, analyzing and interpreting test data;
• Proposing modifications and retesting products;
• Qualifying the final product or system;
• Servicing and maintaining equipment;
• Preparing product documentation, writing reports and giving presentations;
• Monitoring a product in use so as to improve on future design.
• Economy;
• Safety;
• Reliability;
• Quality;
• Sustainability
They are involved in projects from the concept and detail of the design through to implementation, testing and handover.
Most electrical engineers work in a multi-disciplinary project team, including engineers from other specialisms, as well as architects, marketing and sales staff, manufacturers, technicians and customer service personnel.
Electrical engineers need technical knowledge as well as the ability to project manage and multitask. Additional attributes, such as team leadership skills and commercial awareness, are required as careers progress.
» Typical Work Activities
Many organizations now operate cross-functional teams in which the electrical engineer is involved at every stage of design and development in collaboration with colleagues in other engineering functions, as well as those working in production, research, marketing and after-sales services.
The nature of the role varies according to industry or sector, but the range of activities common to many posts is likely to include the following:
• Identifying customer requirements;
• Designing systems and products;
• Reading design specifications and technical drawings;
• Researching suitable solutions and estimating costs and timescales;
• Making models and prototypes of products;
• Working to BS and EN standards;
• Liaising with others in the design team;
• Liaising with clients and contractors;
• Attending meetings on site;
• Designing and conducting tests;
• Recording, analyzing and interpreting test data;
• Proposing modifications and retesting products;
• Qualifying the final product or system;
• Servicing and maintaining equipment;
• Preparing product documentation, writing reports and giving presentations;
• Monitoring a product in use so as to improve on future design.
ENCLOSURE CLASSIFICATIONS
Industry Standards
Enclosure Types for All Locations
National Electrical Manufacturers Association (NEMA Standard 250)
NEMA/EEC to IEC
TYPE Intended Use & Description
Type 1 General purpose enclosures are suitable for general purpose application indoors, where atmospheric conditions are normal. These enclosures serve as protection against falling dust, but are not dust tight.
Type 2 Drip tight (indoor) enclosures are similar to NEMA 1 enclosures, with the addition for drip shields, and are suitable for application where condensation may be severe, such as that encountered in cooling rooms or laundries.
Type 3 Dust, rain proof and sleet resistant enclosures provide proper protection against windblown dust and weather hazards such as rain, sleet or snow. They are suitable for applications outdoors on ship docks, canal locks, construction work, and for applications in subways and tunnels; use indoors where dripping water is a problem.
Type 3R Dust, rain proof and sleet resistant enclosures provide proper protection against falling dirt and weather hazards such as rain, sleet or snow. They are suitable for applications outdoors on ship docks, canal locks, construction work, and for applications in subways and tunnels; use indoors where dripping water is a problem.
Type 4 Water tight enclosures are suitable for dairies, breweries, etc., where the enclosure may be subjected to large amounts of water from any angle. (They are not submersible)
Type 4X Corrosion resistant enclosures satisfy the same requirements as NEMA 4; in addition they are suitable for food processing plants, dairies, refineries, and other industries where corrosion is prominent.
Type 6 Submersible enclosures are suitable for application where the equipment may be subject to submersion, such as quarries, mines, and manholes. The enclosure design will depend upon the specified conditions of pressure and time.
Type 9 Hazardous location enclosures - Class II, Group E, F or G. These enclosures are designed to meet the requirements of the "Canadian Electrical Code" Part I for Class II hazardous locations, and CSA codes section 18 Class II Group E,F, and G.
Class II Group E - atmosphere containing metal dust
Class II Group F - atmosphere containing carbon black, coal, or coke dust.
Class II Group G - atmosphere containing flour, starch or grain dust.
Type 12 Industrial use enclosures are oil tight. Hammond type 12 enclosures meet JIC standard and also satisfy requirements of NEMA.
Type 13 The cover is held in place with screws, bolts or other suitable fasteners, with a continuous gasket construction. The fastener parts are held captive when the door is opened. There are no holes through the enclosures for mounting or attaching controls inside the enclosure, and no conduit knock-outs or openings. Mounting feet, brackets, or other mounting means are provided. These enclosures are suitable for application to machine tools and other industrial processing machines where oil, coolants, water, filings, dust or lint may enter, seep into or infiltrate the enclosure through mounting holes, unused conduit knock-outs, or holes used for mounting equipment with the enclosure.
The preceding descriptions are not intended to be complete representations
of the National Electrical Manufacturers Association standards for enclosures.
Underwriter Laboratories Inc. (UL 50 and UL 508)
TYPE Intended Use and Description (Approximate IP equivalents)
Type 1 Indoor use primarily to provide protection against contact with the enclosed equipment and against limited amount of falling dirt (IP30).
Type 2 Indoor use to provide a degree of protection against limited amounts of falling water and dirt (IP31).
Type 3 Outdoor use to provide a degree of protection against windblown dust and windblown rain; undamaged by the formation of ice on the enclosure (IP64).
Type 3R Outdoor use to provide a degree of protection against falling rain and sleet; undamaged by the formation of ice on the enclosure (IP32).
Type 3S Outdoor use to provide a degree of protection against windblown dust, rain and sleet; external mechanisms remain operable while ice laden.
Type 4 Either indoor or outdoor use to provide a degree of protection against falling rain, splashing water, and hose-directed water; undamaged by the formation of ice on the enclosure(IP66).
Type 4X Same as type 4 except this one is corrosion resistant (IP66).
Type 6 Indoor or outdoor use to provide a degree of protection against entry of water during temporary submersion at a limited depth; undamaged by formation of ice on the enclosure.
Type 6P Indoor or outdoor use to provide a degree of protection against entry of water during prolong submersion at a limited depth.
Type 11 Indoor use to provide by oil immersion a degree of protection of the enclosed equipment against the corrosive effects of corrosive liquids and gases.
Type 12/12K Indoor use to provide a degree of protection against dust, falling dirt, fiber flyings, dripping water, and external condensation or dripping of non corrosive liquids (IP65).
Type 13 Indoor use to provide a degree of protection against lint, dust seepage, external condensation and spraying of water, oil, and non corrosive liquids (IP65).
If there is anything you would like to add or if you have any comments please feel free to email at electrical_engineer@alriyadh.cc
Enclosure Types for All Locations
National Electrical Manufacturers Association (NEMA Standard 250)
NEMA/EEC to IEC
TYPE Intended Use & Description
Type 1 General purpose enclosures are suitable for general purpose application indoors, where atmospheric conditions are normal. These enclosures serve as protection against falling dust, but are not dust tight.
Type 2 Drip tight (indoor) enclosures are similar to NEMA 1 enclosures, with the addition for drip shields, and are suitable for application where condensation may be severe, such as that encountered in cooling rooms or laundries.
Type 3 Dust, rain proof and sleet resistant enclosures provide proper protection against windblown dust and weather hazards such as rain, sleet or snow. They are suitable for applications outdoors on ship docks, canal locks, construction work, and for applications in subways and tunnels; use indoors where dripping water is a problem.
Type 3R Dust, rain proof and sleet resistant enclosures provide proper protection against falling dirt and weather hazards such as rain, sleet or snow. They are suitable for applications outdoors on ship docks, canal locks, construction work, and for applications in subways and tunnels; use indoors where dripping water is a problem.
Type 4 Water tight enclosures are suitable for dairies, breweries, etc., where the enclosure may be subjected to large amounts of water from any angle. (They are not submersible)
Type 4X Corrosion resistant enclosures satisfy the same requirements as NEMA 4; in addition they are suitable for food processing plants, dairies, refineries, and other industries where corrosion is prominent.
Type 6 Submersible enclosures are suitable for application where the equipment may be subject to submersion, such as quarries, mines, and manholes. The enclosure design will depend upon the specified conditions of pressure and time.
Type 9 Hazardous location enclosures - Class II, Group E, F or G. These enclosures are designed to meet the requirements of the "Canadian Electrical Code" Part I for Class II hazardous locations, and CSA codes section 18 Class II Group E,F, and G.
Class II Group E - atmosphere containing metal dust
Class II Group F - atmosphere containing carbon black, coal, or coke dust.
Class II Group G - atmosphere containing flour, starch or grain dust.
Type 12 Industrial use enclosures are oil tight. Hammond type 12 enclosures meet JIC standard and also satisfy requirements of NEMA.
Type 13 The cover is held in place with screws, bolts or other suitable fasteners, with a continuous gasket construction. The fastener parts are held captive when the door is opened. There are no holes through the enclosures for mounting or attaching controls inside the enclosure, and no conduit knock-outs or openings. Mounting feet, brackets, or other mounting means are provided. These enclosures are suitable for application to machine tools and other industrial processing machines where oil, coolants, water, filings, dust or lint may enter, seep into or infiltrate the enclosure through mounting holes, unused conduit knock-outs, or holes used for mounting equipment with the enclosure.
The preceding descriptions are not intended to be complete representations
of the National Electrical Manufacturers Association standards for enclosures.
Underwriter Laboratories Inc. (UL 50 and UL 508)
TYPE Intended Use and Description (Approximate IP equivalents)
Type 1 Indoor use primarily to provide protection against contact with the enclosed equipment and against limited amount of falling dirt (IP30).
Type 2 Indoor use to provide a degree of protection against limited amounts of falling water and dirt (IP31).
Type 3 Outdoor use to provide a degree of protection against windblown dust and windblown rain; undamaged by the formation of ice on the enclosure (IP64).
Type 3R Outdoor use to provide a degree of protection against falling rain and sleet; undamaged by the formation of ice on the enclosure (IP32).
Type 3S Outdoor use to provide a degree of protection against windblown dust, rain and sleet; external mechanisms remain operable while ice laden.
Type 4 Either indoor or outdoor use to provide a degree of protection against falling rain, splashing water, and hose-directed water; undamaged by the formation of ice on the enclosure(IP66).
Type 4X Same as type 4 except this one is corrosion resistant (IP66).
Type 6 Indoor or outdoor use to provide a degree of protection against entry of water during temporary submersion at a limited depth; undamaged by formation of ice on the enclosure.
Type 6P Indoor or outdoor use to provide a degree of protection against entry of water during prolong submersion at a limited depth.
Type 11 Indoor use to provide by oil immersion a degree of protection of the enclosed equipment against the corrosive effects of corrosive liquids and gases.
Type 12/12K Indoor use to provide a degree of protection against dust, falling dirt, fiber flyings, dripping water, and external condensation or dripping of non corrosive liquids (IP65).
Type 13 Indoor use to provide a degree of protection against lint, dust seepage, external condensation and spraying of water, oil, and non corrosive liquids (IP65).
If there is anything you would like to add or if you have any comments please feel free to email at electrical_engineer@alriyadh.cc
PROJECT MANAGEMENT
A successful project starts with solid planning and ends with a smooth hand-off…
The phrases “on time” and “within budget” are often used in discussions of project delivery, but how often can they actually be used to describe a project? Project schedules can fall apart for any number of reasons, but it's often a case of poor planning and a lack of communication. And if participants have uncommon goals or are left out of the early planning stages, a project can be doomed from the start. The lesson to be learned is that early decisions — both good and bad — have a cascading effect throughout the entire life of the project. Taking the time to establish a well-thought-out plan before the first drawing is printed may seem daunting, but it can help you improve both your budget and schedule performance by 30% or more.
Industry-wide studies conducted by the Philadelphia - based Center for Business Practices (CBP) found that organizations that implemented project-planning initiatives report a 34% improvement in schedule performance, a 30% improvement in budget performance, and a 50% increase in projects completed.
You may not want to take the time to put together a formal plan, but the alternative could be even less desirable. When our firm was contracted to install the electrical portion of a food processing plant, we learned just what kind of an effect poor planning can have. Not only did the various trades not coordinate well with each other, nobody knew who was responsible for completing important tasks on the job. Part way through the project, we discovered large gaps where critical tasks hadn't been assigned to anyone, and other areas where the same task had been assigned to multiple groups. This created mass confusion for all. By the time the project reached completion, the value of our contract had doubled due to extra work and change orders.
The extra money you can make on all those change orders may seem worth it, but it can come back to bite you in the long run. Change orders interrupt or alter the original work sequence and result in additional coordination and planning. They can also extend the use of tools and labor. Sometimes, they may even require you to completely redo your work.
Even a project as simple as switching out light fixtures and outlets requires adequate planning to be successful. It can be very time consuming and expensive to use a trial and error method (Fig. 1). Moving things around and making changes is much easier on paper than it is once you've got the space torn apart. The dry-waller, painter, and electrician must all do their part to make everything come together in a smooth manner.
Whether you're wiring a new office building or retrofitting a multi-million dollar processing plant, the four keys to completing the project successfully are the same.
Key #1: Determine the Overall Goal of the Project. Are you trying to improve the light levels in an office or change the electrical wiring to fit a new room layout? Does the industrial facility want to increase production capacity, improve safety, or reduce utility costs? Focus on the ultimate business goal rather than simply how to complete your given task.
The cost and duration of a project can slowly rise unnoticed until it's too late, so make sure that you understand and define a successful “complete project” so everyone involved — including the owner — is aware of expectations. Early planning and collaboration between the electrical professional and everyone else involved can take into consideration issues like reliability, upgrades, change readiness, operating costs, and energy savings. A good plan will help everyone win, including the customer and the other contractors involved.
Key #2: Get All the Right People Involved Early. Everyone participating in the project must be involved and up-to-date from the beginning. Call a meeting and share all pertinent project information with other subcontractors, suppliers, internal engineering groups, accountants, and maintenance personnel. Early feedback from the assembled team regarding the design can go a long way in both adding value and preventing potential snags farther down the road (Fig. 2). It's much easier to make adjustments to the project/schedule now than later.
Each project has dependencies that need to be mapped out. For example, during office construction, it would be problematic if the electrician didn't know where each office was going to be located in the final layout or if the painter and dry-waller had not received a copy of his work schedule. The carpenter must put up the stud walls before the electrician can rough in the wiring. The painter can't begin until the drywall has been mudded and sanded. Carpeting can't be ordered until the office dimensions and layouts are known.
Trade coordination is especially important to a project in a processing plant. Many parts of a process plant must interface or other components will be negatively affected. One of our firm's recent projects faced both budgetary and technical challenges. By having engineering, construction, instrumentation, and control engineering work together on designing intrinsically safe instrumentation and control hardware in a hazardous area, we found that although more was spent on the initial devices, the reduced wiring costs that resulted (conventional instead of classified) not only compensated for the additional hardware cost but also resulted in overall savings on the project. On top of that, this design now allows the owner to maintain the equipment during operations in the sensitive area.
A big part of getting people involved is also getting their buy-in. Involving everyone in early discussion and decision-making creates a sense of ownership. When people understand why a decision was made, what's considered successful, and feel that their concerns have been adequately addressed; they'll be much more willing to cooperate. This sense of ownership will lead them away from a “looking out for me” mentality and promote overall project success.
Key #3: Coordinate and Communicate — the Earlier the Better. Having a plan is great but it's not worth the paper it's printed on if no one follows it. Owner involvement is the key to ensuring that the plan is followed. Explain what needs to happen when and what the consequences will be if the schedule isn't adhered to.
Often once the “what” of the project is completed, the owner steps out and isn't involved in the “how.” All that matters is that it gets done. As one player among many, electrical contractors are very dependent on others to complete their work.
It's very important to make sure that the owner understands how important each piece in the schedule is to the ultimate success of the project. The owner can then hold everyone accountable and make sure things get done when and how they're supposed to.
Knowing when things are going to happen allows team members to better schedule their time and resources. A Contractor Productivity Survey reported highly improved productivity when their field managers planned for resources more than five days in advance. Early & consistent planning & communication will help identify the team's concerns & resource conflicts early enough to adjust without causing many problems.
During another recent project, our firm needed to install 2,000 feet of conduit within the concrete foundation, all during a very aggressive plant shutdown. By planning effectively, we were able to identify problems early, like drawing errors regarding existing conduit and concrete pier locations, trade stacking, and scheduling inconsistencies, that wouldn't have been discovered until installation. Instead of putting the entire project behind schedule, working closely with the other contractors helped cut three days out of the shutdown schedule.
Unforeseen issues always come up and put people behind schedule. But when the owner stays involved in the project schedule and everyone on the team communicates effectively, it's much easier to manage expectations and adapt accordingly.
Key #4: Hand Off the Completed Project. A complex industrial project can be a once in a lifetime opportunity, so getting things right is critical. And a chief component of that is making sure that the right personnel are involved in the project wrap-up. Too often, while the installer is busy testing the equipment and making sure things are running smoothly, the people that will be responsible for operating the plant when they leave are busy painting railings, sweeping floors, or simply not around.
It's not enough to just get the owner's approval. You must also set up the appropriate support system to help those who will take over. Training and support can often leave a lasting impression on those who now have to operate and maintain the newly installed equipment. Appropriate documentation will make future support and maintenance much easier and also simplify the work for the next person who might have to modify your work.
No project goes exactly as planned, but it will be much easier to resolve problems if you understand the overall project goal, get early input from everyone involved, make sure people are communicating and working together, and leave behind an appropriate support system. These keys will go a long way in helping you achieve your “on time” and “within budget” goals.
The phrases “on time” and “within budget” are often used in discussions of project delivery, but how often can they actually be used to describe a project? Project schedules can fall apart for any number of reasons, but it's often a case of poor planning and a lack of communication. And if participants have uncommon goals or are left out of the early planning stages, a project can be doomed from the start. The lesson to be learned is that early decisions — both good and bad — have a cascading effect throughout the entire life of the project. Taking the time to establish a well-thought-out plan before the first drawing is printed may seem daunting, but it can help you improve both your budget and schedule performance by 30% or more.
Industry-wide studies conducted by the Philadelphia - based Center for Business Practices (CBP) found that organizations that implemented project-planning initiatives report a 34% improvement in schedule performance, a 30% improvement in budget performance, and a 50% increase in projects completed.
You may not want to take the time to put together a formal plan, but the alternative could be even less desirable. When our firm was contracted to install the electrical portion of a food processing plant, we learned just what kind of an effect poor planning can have. Not only did the various trades not coordinate well with each other, nobody knew who was responsible for completing important tasks on the job. Part way through the project, we discovered large gaps where critical tasks hadn't been assigned to anyone, and other areas where the same task had been assigned to multiple groups. This created mass confusion for all. By the time the project reached completion, the value of our contract had doubled due to extra work and change orders.
The extra money you can make on all those change orders may seem worth it, but it can come back to bite you in the long run. Change orders interrupt or alter the original work sequence and result in additional coordination and planning. They can also extend the use of tools and labor. Sometimes, they may even require you to completely redo your work.
Even a project as simple as switching out light fixtures and outlets requires adequate planning to be successful. It can be very time consuming and expensive to use a trial and error method (Fig. 1). Moving things around and making changes is much easier on paper than it is once you've got the space torn apart. The dry-waller, painter, and electrician must all do their part to make everything come together in a smooth manner.
Whether you're wiring a new office building or retrofitting a multi-million dollar processing plant, the four keys to completing the project successfully are the same.
Key #1: Determine the Overall Goal of the Project. Are you trying to improve the light levels in an office or change the electrical wiring to fit a new room layout? Does the industrial facility want to increase production capacity, improve safety, or reduce utility costs? Focus on the ultimate business goal rather than simply how to complete your given task.
The cost and duration of a project can slowly rise unnoticed until it's too late, so make sure that you understand and define a successful “complete project” so everyone involved — including the owner — is aware of expectations. Early planning and collaboration between the electrical professional and everyone else involved can take into consideration issues like reliability, upgrades, change readiness, operating costs, and energy savings. A good plan will help everyone win, including the customer and the other contractors involved.
Key #2: Get All the Right People Involved Early. Everyone participating in the project must be involved and up-to-date from the beginning. Call a meeting and share all pertinent project information with other subcontractors, suppliers, internal engineering groups, accountants, and maintenance personnel. Early feedback from the assembled team regarding the design can go a long way in both adding value and preventing potential snags farther down the road (Fig. 2). It's much easier to make adjustments to the project/schedule now than later.
Each project has dependencies that need to be mapped out. For example, during office construction, it would be problematic if the electrician didn't know where each office was going to be located in the final layout or if the painter and dry-waller had not received a copy of his work schedule. The carpenter must put up the stud walls before the electrician can rough in the wiring. The painter can't begin until the drywall has been mudded and sanded. Carpeting can't be ordered until the office dimensions and layouts are known.
Trade coordination is especially important to a project in a processing plant. Many parts of a process plant must interface or other components will be negatively affected. One of our firm's recent projects faced both budgetary and technical challenges. By having engineering, construction, instrumentation, and control engineering work together on designing intrinsically safe instrumentation and control hardware in a hazardous area, we found that although more was spent on the initial devices, the reduced wiring costs that resulted (conventional instead of classified) not only compensated for the additional hardware cost but also resulted in overall savings on the project. On top of that, this design now allows the owner to maintain the equipment during operations in the sensitive area.
A big part of getting people involved is also getting their buy-in. Involving everyone in early discussion and decision-making creates a sense of ownership. When people understand why a decision was made, what's considered successful, and feel that their concerns have been adequately addressed; they'll be much more willing to cooperate. This sense of ownership will lead them away from a “looking out for me” mentality and promote overall project success.
Key #3: Coordinate and Communicate — the Earlier the Better. Having a plan is great but it's not worth the paper it's printed on if no one follows it. Owner involvement is the key to ensuring that the plan is followed. Explain what needs to happen when and what the consequences will be if the schedule isn't adhered to.
Often once the “what” of the project is completed, the owner steps out and isn't involved in the “how.” All that matters is that it gets done. As one player among many, electrical contractors are very dependent on others to complete their work.
It's very important to make sure that the owner understands how important each piece in the schedule is to the ultimate success of the project. The owner can then hold everyone accountable and make sure things get done when and how they're supposed to.
Knowing when things are going to happen allows team members to better schedule their time and resources. A Contractor Productivity Survey reported highly improved productivity when their field managers planned for resources more than five days in advance. Early & consistent planning & communication will help identify the team's concerns & resource conflicts early enough to adjust without causing many problems.
During another recent project, our firm needed to install 2,000 feet of conduit within the concrete foundation, all during a very aggressive plant shutdown. By planning effectively, we were able to identify problems early, like drawing errors regarding existing conduit and concrete pier locations, trade stacking, and scheduling inconsistencies, that wouldn't have been discovered until installation. Instead of putting the entire project behind schedule, working closely with the other contractors helped cut three days out of the shutdown schedule.
Unforeseen issues always come up and put people behind schedule. But when the owner stays involved in the project schedule and everyone on the team communicates effectively, it's much easier to manage expectations and adapt accordingly.
Key #4: Hand Off the Completed Project. A complex industrial project can be a once in a lifetime opportunity, so getting things right is critical. And a chief component of that is making sure that the right personnel are involved in the project wrap-up. Too often, while the installer is busy testing the equipment and making sure things are running smoothly, the people that will be responsible for operating the plant when they leave are busy painting railings, sweeping floors, or simply not around.
It's not enough to just get the owner's approval. You must also set up the appropriate support system to help those who will take over. Training and support can often leave a lasting impression on those who now have to operate and maintain the newly installed equipment. Appropriate documentation will make future support and maintenance much easier and also simplify the work for the next person who might have to modify your work.
No project goes exactly as planned, but it will be much easier to resolve problems if you understand the overall project goal, get early input from everyone involved, make sure people are communicating and working together, and leave behind an appropriate support system. These keys will go a long way in helping you achieve your “on time” and “within budget” goals.
Thursday, December 13, 2007
ACHIEVE IT! QUOTES
"Aim for success not perfection... Remember that fear always lurks behind perfectionism. Confronting your fears and allowing yourself the right to be human can, paradoxically, make you a far happier and more productive person." - Dr. David Burns
"The secret to productive goal setting is in establishing clearly defined goals, writing them down and then focusing on them several times a day with words, pictures and emotions as if we've already achieved them." - Denis Waitley
"Your own mind is a sacred enclosure into which nothing harmful can enter except by your permission." - Ralph Waldo Emerson
"Work as though you would live forever, and live as though you would die today" - Og Mandino
"You don't have to be a fantastic hero to do certain things - to compete. You can be just an ordinary chap, sufficiently motivated to reach challenging goals" - Edmund Hillary
"Goals are dreams with deadlines" - Diana Scharf Hunt
"If you're bored with life -- you don't get up every morning with a burning desire to do things -- you don't have enough goals." - Lou Holtz
"Goals are not only absolutely necessary to motivate us. They are essential to really keep us alive." - Robert H. Schuller
"You have to set goals that are almost out of reach. If you set a goal that is attainable without much work or thought, you are stuck with something below your true talent and potential." - Steve Garvey
"You measure the size of the accomplishment by the obstacles you had to overcome to reach your goals." - Booker T. Washington
"It’s always fun to do the impossible." - Walt Disney
"My philosophy of life is that if we make up our mind what we are going to make of our lives, then work hard toward that goal, we never lose - somehow we win out." - Ronald Regan
"Goals. There's not telling what you can do when you get inspired by them. There's no telling what you can do when you believe in them. There's no telling what will happen when you act upon them." - Jim Rohn
"Your goals are the road maps that guide you and show you what is possible for your life." - Les Brown
"Big goals get big results. No goals get no results or somebody else's results." - Mark Victor Hansen
"Goals give you more than a reason to get up in the morning; they are an incentive to keep you going all day. Goals tend to tap the deeper resources and draw the best out of life." - Harvey Mackay
"Emptiness is a symptom that you are not living creatively. You either have not goal that is important enough to you, or you are not using your talents and efforts in a striving toward an important goal." - Maxwell Maltz
"Remember, what you get by reaching your destination isn't nearly as important as what you become by reaching your goals -- what you will become is the winner you were born to be!" - Zig Ziglar
"If you aim at nothing, you'll hit it every time." – Anonymous
"All you have to do is know where you're going. The answers will come to you of their own accord." - Earl Nightingale
"The secret to productive goal setting is in establishing clearly defined goals, writing them down and then focusing on them several times a day with words, pictures and emotions as if we've already achieved them." - Denis Waitley
"Your own mind is a sacred enclosure into which nothing harmful can enter except by your permission." - Ralph Waldo Emerson
"Work as though you would live forever, and live as though you would die today" - Og Mandino
"You don't have to be a fantastic hero to do certain things - to compete. You can be just an ordinary chap, sufficiently motivated to reach challenging goals" - Edmund Hillary
"Goals are dreams with deadlines" - Diana Scharf Hunt
"If you're bored with life -- you don't get up every morning with a burning desire to do things -- you don't have enough goals." - Lou Holtz
"Goals are not only absolutely necessary to motivate us. They are essential to really keep us alive." - Robert H. Schuller
"You have to set goals that are almost out of reach. If you set a goal that is attainable without much work or thought, you are stuck with something below your true talent and potential." - Steve Garvey
"You measure the size of the accomplishment by the obstacles you had to overcome to reach your goals." - Booker T. Washington
"It’s always fun to do the impossible." - Walt Disney
"My philosophy of life is that if we make up our mind what we are going to make of our lives, then work hard toward that goal, we never lose - somehow we win out." - Ronald Regan
"Goals. There's not telling what you can do when you get inspired by them. There's no telling what you can do when you believe in them. There's no telling what will happen when you act upon them." - Jim Rohn
"Your goals are the road maps that guide you and show you what is possible for your life." - Les Brown
"Big goals get big results. No goals get no results or somebody else's results." - Mark Victor Hansen
"Goals give you more than a reason to get up in the morning; they are an incentive to keep you going all day. Goals tend to tap the deeper resources and draw the best out of life." - Harvey Mackay
"Emptiness is a symptom that you are not living creatively. You either have not goal that is important enough to you, or you are not using your talents and efforts in a striving toward an important goal." - Maxwell Maltz
"Remember, what you get by reaching your destination isn't nearly as important as what you become by reaching your goals -- what you will become is the winner you were born to be!" - Zig Ziglar
"If you aim at nothing, you'll hit it every time." – Anonymous
"All you have to do is know where you're going. The answers will come to you of their own accord." - Earl Nightingale
Tuesday, December 11, 2007
GENERAL SPECIFICATION FOR LV SWITCHBOARDS
PART 1 - GENERAL
1.01 DESCRIPTION
A. This section covers the manufacture, furnish, installation and testing of all equipment, accessories and materials required for the installation of LV Switchboards (Type Tested Assemblies) in accordance with the specifications and drawings.
1.02 APPLICABLE CODES AND STANDARDS
A. The work shall be carried out in accordance with this specification, the contract drawings and the standards listed hereunder.
The following codes and standards provide an acceptable level of quality for materials and products:
1. SASO 1609 Saudi Standard for low voltage switchgear and controlgear
assemblies-Part 1 : Type tested and partially type tested assemblies
2. IEC 60439-1 Low voltage switchgear and controlgear assemblies-
Part 1 : Type tested and partially type tested assemblies
3. IEC 60529 Degrees of protection provided by enclosure (IP Code)
1.03 QUALITY ASSURANCE
A. All materials and products shall be new, sound and uniform in quality, size, shape, color and texture and shall be free from defects.
B. The contractor shall be responsible for ensuring that the required standards of quality control as mentioned in relative sections are maintained for the proposed switchboards.
C. If requested by the Ministry, the supplier shall provide proof of application of a quality procedure complying with standards. This means:
1. use of a quality manual approved and signed by a management representative,
2. regular updating of this manual so that it reflects the most recent applicable quality control procedures,
3. ISO 9002 certification.
D. The manufacturer must have a sound experience in the field of LV switchboards for not less than ten years, and should have a presentable reference list of the already supplied equipment of the same type and same make and that this equipment has been in satisfactory operation in Kingdom of Saudi Arabia for at least five years.
1.04 SUBMITTAL
A. Shop Drawings and Manufacturer's Data:
The contractor shall submit to the Ministry representative for review, detailed dimensioned shop drawings and manufacturer's literature where deviations from the contract drawings or specification exist. Shop drawings and/or data sheets shall be based on information stated in the specifications and as shown on the contract drawings and shall show all pertinent deviations and data for the fabrication and complete installation.
Manufacturer's data sheets shall be submitted indicating the necessary installation dimensions, weights, materials and performance information. The above information may be provided by standard catalogue sheets marked to indicate the specific items provided.
B. Operation and Maintenance Instructions:
The contractor shall furnish data covering model, type and serial numbers, capacities, maintenance and operation of each major item of equipment or apparatus in accordance with the requirements of the contract documents. Operating instructions shall cover all phases of control.
C. Test Reports:
The contractor shall submit test reports to the Ministry representative for review.
D. Recommended Spare Parts List:
The contractor shall submit recommended spare parts list to the Ministry representative for review.
E. As Built Drawings:
The contractor shall submit the as built drawings to the Ministry representative for review and approval.
1.05 COORDINATION
A. The contractor shall be held responsible for the proper coordination of all phases of the work under this contract.
B. It shall be the responsibility of the contractor to coordinate the work and equipment as specified herein with work to be performed and equipment to be furnished under other sections of the specifications in order to assure a complete and satisfactory installation.
1.06 PRODUCT DELIVERY, STORAGE AND HANDLING
A. Deliver, store, protect and handle products to site as per manufacturer’s instructions.
B. Store swithboards in clean and dry space. Inspect for damage. Maintain factory wrapping or provide an additional heavy canvas or heavy plastic cover to protect units from dirt, water, construction debris and traffic.
C. Lift only with lugs provided for the purpose. Handle carfully to avoid damage to switchboard internal components, enclosure and finish.
PART 2 - PRODUCTION
2.01 GENERAL
A. The following specifications apply to LV Switchboards rated above 250 Amps and upto 4000 Amps, classified as ‘Main Distribution Boards’ and ‘Sub-Main Distribution Boards’.
B. Extensions to the low voltage electrical switchboards shall be possible on either side (right or left).
C. The Switchboard and the associated Switchgear and Controlgear like Circuit Breakers, Contactors, Switches, Meters etc. should be from the same manufacturer.
2.02 TECHNICAL CHARACTERISTIC
A. The switchboards shall be designed and tested for the following electrical values:
1. Rated voltage 1000 V three-phase.
2. Rated operating voltage 690V
3. Frequency 60 Hz.
4. Insulation level 2.5 kV- 60 Hz, 1min
8 kV-1,2/50µs.
5. Busbar rated current As shown on the drawings.
6. Short-circuit withstand current As shown on the drawings.
7. Degree of protection (IP) IP 31 for Indoor Application and IP55 for Outdoor
Application or as indicated on the drawings
8 Impact strength (IK) IK08 for Indoor Application and IK10 for Outdoor Application.
2.03 SERVICE CONDITIONS
A. The switchboard shall be suitable for operations at a height of less than 2000 meters above sea level.
B. The switchboards shall be capable of operating normally within the following temperature range
1. Maximum air temperature + 40 ° C
2. Minimum air temperature - 5 ° C
C. Manufacturer shall declare wether switchboard is able to operate in air temperature higher than + 40 °C and if current derating is necessary.
2.04 CONSTRUCTION AND OPERATION
A. The low voltage switchboard shall have a permissible asymmetrical short circuit current up to short circuit current shown on the drawings for 1 second. The busbars shall be designed for mounting on insulated supports that are sufficient in number to accept the electro-dynamic forces resulting from the flow of the peak asymmetrical short circuit current.
B. The low voltage switchboard shall have an earthing circuit including a bar that can be removed for isolation purposes during the necessary insulation measurements (removal of the bar shall require a tool)
C. The switchboard shall be suitable for front or rear connections.
D. Cable entry shall be via the bottom or the top.
E. The low voltage switchboard shall not be heigher than 2000mm.
F. Natural ventilation shall make it possible for the Switchboard components to operate with in the recommended temperature ranges.
G. The low voltage electrical switchboard shall have small depths, thus optimizing layout in electrical rooms:
1. Max. 400 mm up to 1600A.
2. Max.1200 mm up to 4000 A.
H. The system shall make it possible to implement fixed or withdrawable distribution switchgear.
I. Selection of switchboard components shall be made in compliance with standard IEC 60947 and related specification in the contract documents.
J. The low voltage electrical switchboard shall be made up of identified functional volumes including the busbar compartment, switchgear and controlgear component compartment, connection compartment and auxiliaries compartment.
1. The different types of busbars shall be the main busbars, distribution busbars and auxiliary busbars.
2. The busbars shall be made of electrolytic copper.
3. The compartment shall be located inside a metal enclosure with walls providing protection against direct contact with live parts and guaranteeing a degree of protection (IP) requested. The frame, the external panels (doors, side and rear panels, tops) and internal elements (ducts) shall be made of 1.5-mm thick folded metal steel sheet and protected by epoxy polyester powder paint coating.
K. Withdrawable circuit breakers shall have four different positions:
1. Connected
2. Test
3. Disconnected
4. Removed
L. The switchboard shall be suitable for installation side by side and back to back and capable of receiving lateral ducts for busbar, cables and terminals.
M. The switchboard cover panel shall be removable.
N. The construction system shall provide a complete set of elements for installing fixed or withdrawable switching and protective devices, measurement devices and control/ monitoring devices in the switchboard.
2.05 Protection and safety
A. The low voltage electrical switchboards shall ensure the safety of life and property as well as provide a high level of continuity to service
1. Switching safety shall be ensured by mechanical device preventing on load withdrawal
2. Operating safety shall be ensured by compartmenting in compliance with standard IEC 60439-1 and according to Form 2b. However, if specifically asked, the same Switchboard should be capable of upgrading to Form 3a, 3b, 4a or 4b.
3. Current interruption shall be of the “ visible break isolation “or “positive contact indication “type as defined by standard IEC 60947-3.
B. In view of reducing the risk of electrical shock
1. Power and control circuit shall be separate and completely isolated.
2. Auxiliary circuits shall be of the extra low voltage type.
2.06 TYPE TESTS AND ROUTINE TESTS
A. Routine Tests
The switchboard shall be subject to Routine Factory Test carried out by the Panelbuilder and shall be substantiated by a test report signed by the factory quality control department., in accordance with IEC 60439 –1 as follows:
1. Conformity with drawings and diagrams.
2. Visual Inspection.
3. Functional electrical and mechanical operation
4. Dielectric test.
B. Type Tests
In accordance with IEC 60439 –1, the Switchboard Design must have qualified fully to the Seven Type-Tests detailed below, conducted by an Accredited Independent Testing Laboratory like ASEFA, ASTA, KEMA etc. Certificates for each Test shall be submitted to the Ministry Representative for Review.
1. Temperature-rise test.
2. Dielectric test.
3. Short-circuit withstand test.
4. Effectiveness of the protective circuits test.
5. Clearance and creepage distance test.
6. Mechanical operation test.
7. Degree of protection test.
PART 3 - EXECUTION
3.01 WORKMANSHIP
A. Materials, products and equipment furnished by the contractor, shall be installed and all work shall be performed in a first-class workmanship manner, in conformity with the best trade practices and the printed directions of the applicable manufacturers; by skilled workers equipped to produce satisfactory results; in a safe, substantial manner so as to avoid undue stresses, rigid enough to prevent undue movement, so as to present a neat, orderly appearance and to facilitate operating, servicing, maintenance and repairing.
3.02 FOUNDATIONS AND SUPPORTS
A. The contractor shall provide concrete pedestals, anchor bolts, hangers, channels, saddles, etc., for installation of equipment and apparatus shown on the drawings and specified in the various sections.
3.03 EQUIPMENT INSTALLATION
A. All electrical equipment shall be installed in accordance with the manufacturer's recommendations, good electrical engineering practice, and the relevant drawings and specifications.
B. All metal surfaces to be bolted shall be thoroughly cleaned before assembly. The connections shall be tightened with manual torque wrenches to the manufacturer's erection instructions.
C. Splices shall be implemented to ensure the electrical continuity of the horizontal busbars, auxiliary buses and the proactive conductor between adjacent sections.
D. It shall be possible to secure the sections to a floor that is flat by nchoring directly to a concrete floor using anchor bolts or by securing to ordinary metal profiles.
3.04 EQUIPMENT TESTING AND COMMISSIONING
A. After the installation is complete and properly adjusted, the contractor shall conduct operating tests. The various equipment and systems shall be demonstrated to operate in accordance with the requirements of the contract documents. Tests shall be performed in the presence of the client/client representative. The contractor shall provide electric power, instruments and personnel necessary for performing the various tests.
B. The testing of all electrical equipment shall include, but not be limited to, the items below. This shall be in addition to testing specified elsewhere in this specification.
1. General equipment check.
2. Field wiring and ground system verification.
3. Equipment adjustment.
1.01 DESCRIPTION
A. This section covers the manufacture, furnish, installation and testing of all equipment, accessories and materials required for the installation of LV Switchboards (Type Tested Assemblies) in accordance with the specifications and drawings.
1.02 APPLICABLE CODES AND STANDARDS
A. The work shall be carried out in accordance with this specification, the contract drawings and the standards listed hereunder.
The following codes and standards provide an acceptable level of quality for materials and products:
1. SASO 1609 Saudi Standard for low voltage switchgear and controlgear
assemblies-Part 1 : Type tested and partially type tested assemblies
2. IEC 60439-1 Low voltage switchgear and controlgear assemblies-
Part 1 : Type tested and partially type tested assemblies
3. IEC 60529 Degrees of protection provided by enclosure (IP Code)
1.03 QUALITY ASSURANCE
A. All materials and products shall be new, sound and uniform in quality, size, shape, color and texture and shall be free from defects.
B. The contractor shall be responsible for ensuring that the required standards of quality control as mentioned in relative sections are maintained for the proposed switchboards.
C. If requested by the Ministry, the supplier shall provide proof of application of a quality procedure complying with standards. This means:
1. use of a quality manual approved and signed by a management representative,
2. regular updating of this manual so that it reflects the most recent applicable quality control procedures,
3. ISO 9002 certification.
D. The manufacturer must have a sound experience in the field of LV switchboards for not less than ten years, and should have a presentable reference list of the already supplied equipment of the same type and same make and that this equipment has been in satisfactory operation in Kingdom of Saudi Arabia for at least five years.
1.04 SUBMITTAL
A. Shop Drawings and Manufacturer's Data:
The contractor shall submit to the Ministry representative for review, detailed dimensioned shop drawings and manufacturer's literature where deviations from the contract drawings or specification exist. Shop drawings and/or data sheets shall be based on information stated in the specifications and as shown on the contract drawings and shall show all pertinent deviations and data for the fabrication and complete installation.
Manufacturer's data sheets shall be submitted indicating the necessary installation dimensions, weights, materials and performance information. The above information may be provided by standard catalogue sheets marked to indicate the specific items provided.
B. Operation and Maintenance Instructions:
The contractor shall furnish data covering model, type and serial numbers, capacities, maintenance and operation of each major item of equipment or apparatus in accordance with the requirements of the contract documents. Operating instructions shall cover all phases of control.
C. Test Reports:
The contractor shall submit test reports to the Ministry representative for review.
D. Recommended Spare Parts List:
The contractor shall submit recommended spare parts list to the Ministry representative for review.
E. As Built Drawings:
The contractor shall submit the as built drawings to the Ministry representative for review and approval.
1.05 COORDINATION
A. The contractor shall be held responsible for the proper coordination of all phases of the work under this contract.
B. It shall be the responsibility of the contractor to coordinate the work and equipment as specified herein with work to be performed and equipment to be furnished under other sections of the specifications in order to assure a complete and satisfactory installation.
1.06 PRODUCT DELIVERY, STORAGE AND HANDLING
A. Deliver, store, protect and handle products to site as per manufacturer’s instructions.
B. Store swithboards in clean and dry space. Inspect for damage. Maintain factory wrapping or provide an additional heavy canvas or heavy plastic cover to protect units from dirt, water, construction debris and traffic.
C. Lift only with lugs provided for the purpose. Handle carfully to avoid damage to switchboard internal components, enclosure and finish.
PART 2 - PRODUCTION
2.01 GENERAL
A. The following specifications apply to LV Switchboards rated above 250 Amps and upto 4000 Amps, classified as ‘Main Distribution Boards’ and ‘Sub-Main Distribution Boards’.
B. Extensions to the low voltage electrical switchboards shall be possible on either side (right or left).
C. The Switchboard and the associated Switchgear and Controlgear like Circuit Breakers, Contactors, Switches, Meters etc. should be from the same manufacturer.
2.02 TECHNICAL CHARACTERISTIC
A. The switchboards shall be designed and tested for the following electrical values:
1. Rated voltage 1000 V three-phase.
2. Rated operating voltage 690V
3. Frequency 60 Hz.
4. Insulation level 2.5 kV- 60 Hz, 1min
8 kV-1,2/50µs.
5. Busbar rated current As shown on the drawings.
6. Short-circuit withstand current As shown on the drawings.
7. Degree of protection (IP) IP 31 for Indoor Application and IP55 for Outdoor
Application or as indicated on the drawings
8 Impact strength (IK) IK08 for Indoor Application and IK10 for Outdoor Application.
2.03 SERVICE CONDITIONS
A. The switchboard shall be suitable for operations at a height of less than 2000 meters above sea level.
B. The switchboards shall be capable of operating normally within the following temperature range
1. Maximum air temperature + 40 ° C
2. Minimum air temperature - 5 ° C
C. Manufacturer shall declare wether switchboard is able to operate in air temperature higher than + 40 °C and if current derating is necessary.
2.04 CONSTRUCTION AND OPERATION
A. The low voltage switchboard shall have a permissible asymmetrical short circuit current up to short circuit current shown on the drawings for 1 second. The busbars shall be designed for mounting on insulated supports that are sufficient in number to accept the electro-dynamic forces resulting from the flow of the peak asymmetrical short circuit current.
B. The low voltage switchboard shall have an earthing circuit including a bar that can be removed for isolation purposes during the necessary insulation measurements (removal of the bar shall require a tool)
C. The switchboard shall be suitable for front or rear connections.
D. Cable entry shall be via the bottom or the top.
E. The low voltage switchboard shall not be heigher than 2000mm.
F. Natural ventilation shall make it possible for the Switchboard components to operate with in the recommended temperature ranges.
G. The low voltage electrical switchboard shall have small depths, thus optimizing layout in electrical rooms:
1. Max. 400 mm up to 1600A.
2. Max.1200 mm up to 4000 A.
H. The system shall make it possible to implement fixed or withdrawable distribution switchgear.
I. Selection of switchboard components shall be made in compliance with standard IEC 60947 and related specification in the contract documents.
J. The low voltage electrical switchboard shall be made up of identified functional volumes including the busbar compartment, switchgear and controlgear component compartment, connection compartment and auxiliaries compartment.
1. The different types of busbars shall be the main busbars, distribution busbars and auxiliary busbars.
2. The busbars shall be made of electrolytic copper.
3. The compartment shall be located inside a metal enclosure with walls providing protection against direct contact with live parts and guaranteeing a degree of protection (IP) requested. The frame, the external panels (doors, side and rear panels, tops) and internal elements (ducts) shall be made of 1.5-mm thick folded metal steel sheet and protected by epoxy polyester powder paint coating.
K. Withdrawable circuit breakers shall have four different positions:
1. Connected
2. Test
3. Disconnected
4. Removed
L. The switchboard shall be suitable for installation side by side and back to back and capable of receiving lateral ducts for busbar, cables and terminals.
M. The switchboard cover panel shall be removable.
N. The construction system shall provide a complete set of elements for installing fixed or withdrawable switching and protective devices, measurement devices and control/ monitoring devices in the switchboard.
2.05 Protection and safety
A. The low voltage electrical switchboards shall ensure the safety of life and property as well as provide a high level of continuity to service
1. Switching safety shall be ensured by mechanical device preventing on load withdrawal
2. Operating safety shall be ensured by compartmenting in compliance with standard IEC 60439-1 and according to Form 2b. However, if specifically asked, the same Switchboard should be capable of upgrading to Form 3a, 3b, 4a or 4b.
3. Current interruption shall be of the “ visible break isolation “or “positive contact indication “type as defined by standard IEC 60947-3.
B. In view of reducing the risk of electrical shock
1. Power and control circuit shall be separate and completely isolated.
2. Auxiliary circuits shall be of the extra low voltage type.
2.06 TYPE TESTS AND ROUTINE TESTS
A. Routine Tests
The switchboard shall be subject to Routine Factory Test carried out by the Panelbuilder and shall be substantiated by a test report signed by the factory quality control department., in accordance with IEC 60439 –1 as follows:
1. Conformity with drawings and diagrams.
2. Visual Inspection.
3. Functional electrical and mechanical operation
4. Dielectric test.
B. Type Tests
In accordance with IEC 60439 –1, the Switchboard Design must have qualified fully to the Seven Type-Tests detailed below, conducted by an Accredited Independent Testing Laboratory like ASEFA, ASTA, KEMA etc. Certificates for each Test shall be submitted to the Ministry Representative for Review.
1. Temperature-rise test.
2. Dielectric test.
3. Short-circuit withstand test.
4. Effectiveness of the protective circuits test.
5. Clearance and creepage distance test.
6. Mechanical operation test.
7. Degree of protection test.
PART 3 - EXECUTION
3.01 WORKMANSHIP
A. Materials, products and equipment furnished by the contractor, shall be installed and all work shall be performed in a first-class workmanship manner, in conformity with the best trade practices and the printed directions of the applicable manufacturers; by skilled workers equipped to produce satisfactory results; in a safe, substantial manner so as to avoid undue stresses, rigid enough to prevent undue movement, so as to present a neat, orderly appearance and to facilitate operating, servicing, maintenance and repairing.
3.02 FOUNDATIONS AND SUPPORTS
A. The contractor shall provide concrete pedestals, anchor bolts, hangers, channels, saddles, etc., for installation of equipment and apparatus shown on the drawings and specified in the various sections.
3.03 EQUIPMENT INSTALLATION
A. All electrical equipment shall be installed in accordance with the manufacturer's recommendations, good electrical engineering practice, and the relevant drawings and specifications.
B. All metal surfaces to be bolted shall be thoroughly cleaned before assembly. The connections shall be tightened with manual torque wrenches to the manufacturer's erection instructions.
C. Splices shall be implemented to ensure the electrical continuity of the horizontal busbars, auxiliary buses and the proactive conductor between adjacent sections.
D. It shall be possible to secure the sections to a floor that is flat by nchoring directly to a concrete floor using anchor bolts or by securing to ordinary metal profiles.
3.04 EQUIPMENT TESTING AND COMMISSIONING
A. After the installation is complete and properly adjusted, the contractor shall conduct operating tests. The various equipment and systems shall be demonstrated to operate in accordance with the requirements of the contract documents. Tests shall be performed in the presence of the client/client representative. The contractor shall provide electric power, instruments and personnel necessary for performing the various tests.
B. The testing of all electrical equipment shall include, but not be limited to, the items below. This shall be in addition to testing specified elsewhere in this specification.
1. General equipment check.
2. Field wiring and ground system verification.
3. Equipment adjustment.
SPECIFICATION FOR LV FINAL DISTRIBUTION BOARDS
PART 1 - GENERAL
1.01 DESCRIPTION
A. This section covers the manufacture, furnish, installation and testing of all equipment, accessories and materials required for the installation of LV Final Distribution Boards rated upto 250 Amps.
1.02 APPLICABLE CODES AND STANDARDS
A. The work shall be carried out in accordance with this specification, the contract drawings and the standards listed hereunder.
The following codes and standards provide an acceptable level of quality for materials and products:
1. SASO 1611 Saudi Standard for Low Voltage Distribution Boards
2. IEC 60439-3 Low voltage Final Distribution Boards.
3. IEC 60529 Degree of Protection provided by the encloure (IP Code)
4. IEC 60947-2 Low Voltage Switchgear and Controlgear – Circuit breakers.
5. IEC 61008-1 Residual Current operated Circuit Breakers without integral Overcurrent Protection (RCCB’s)
6. IEC 61009 Residual Current operated Circuit Breakers with integral
Overcurrent Protection. (RCBO)
1.03 QUALITY ASSURANCE
A. All materials and products shall be new, sound and uniform in quality, size, shape, color and texture and shall be free from defects.
B. The contractor shall be responsible for ensuring that the required standards of quality control as mentioned in relative sections are maintained for the proposed Distribution Boards.
C. The supplier shall provide proof of application of a quality procedure in the manufacturing facility complying with standards. This means:
1. use of a quality manual approved and signed by a management representative,
2. regular updating of this manual so that it reflects the most recent applicable quality control procedures,
3. ISO 9002 certification.
PART 2 - PRODUCTION
2.01 GENERAL
A. These specifications apply to LV Final Distribution Boards rated upto 250 Amps.
B. The Distribution Board and the associated Switchgear and Controlgear like Circuit Breakers, Contactors, Switches, etc. should be from the same manufacturer.
2.02 TECHNICAL CHARACTERISTICS
A. The Distribution Boards shall be designed and tested for the following electrical values:
1. Rated Insulation Voltage 690 V AC.
2. Rated Operating Voltage 415 V AC.
3. Frequency 50/60 Hz.
4. Busbar rated current upto 250 Amps. (or as indicated on the drawings)
5. Short-time withstand current 17 kA RMS for 200ms.
6. Peak Short Time withstand 34 kA
7. Degree of protection (IP) IP31 as per IEC 60529
2.03 CONSTRUCTION AND OPERATION
A. Metal enclosure of the low-voltage distribution board shall be made of electro galvanised steel sheet metal without any welding Points which shall have received an anti-corrosion coating (hot polymerised polyester/epoxy powder).
B. One central slotted hole should be provided to ease accurate levelling of the distribution board.
C. Additional slotted holes for ease at wall fixing should be provided.
D. The front face of the switchboards shall be removable to facilitate servicing.
E. Removable gland plate should be available at the top and the bottom of the distribution board
F. Cable knockouts should be available on sides, top and bottom of the distribution board for quicker and easier installation.
G. Main busbar should be made of tin-plated copper and fully shrouded.
H. Main busbar, in vertical position, should be installed into a rigid and adjustable suspended pan assembly.
I. In order to provide easy connection and maximum cable space, split neutral bars should be provided as standard in both sides.
J. Earth bar should be provided as standard.
K. Number of holes per terminal bar should not be less than the number of outgoings.
L. Switchgear and controlgear should be of DIN installation type.
M. Switchgear and controlgear connections to the busbar should be of bolt-on type.
2.04 PROTECTION AND SAFETY
A. The main busbar of the Distribution Board should be fully shrouded to prevent any accidental direct contact.
B. The split neutral busbar should be completely shrouded to prevent any accidental direct contact.
C. The Main Incoming Circuit-Breakers should provide additional Earth Leakage Protection. All the protection features of the Main Circuit Breaker, including Earth Leakage Protection, should be in full discrimination with those of the outgoing feeders (as per the relevant clauses of IEC 60947-2, IEC 61008 and IEC 61009) to minimise the isolation of a faulty part of the network.
D. All outgoing feeders to bathrooms, socket-outlets, AC units and Heaters should be provided with Residual Current Protection Devices for protection against direct and indirect contact, which should be coordinated with the Earth Protection of the Main Incoming Circuit Breaker.
E. All incoming switchgears should be suitable for isolation as per IEC 60947-2.
F. For critical loads requiring Continuity of Supply, all outgoing Branch Circuit-Breakers should be connected to the Main Bus bar by a fully shrouded OFF-LOAD Isolating Switch which should facilitate the replacement or removal of this Branch Breaker without de-energisation of the Distribution Board or any of the other adjacent Branches, and also provide complete protection against a direct contact with any energised part of the Distribution Board.
G. Keylock facility should be available in order to prevent the opening of the distribution board by non authorized persons.
H. Keylock should be field installable.
2.05 INDICATION
A. Identification labels should be provided for incoming and outgoing circuits, earth and neutral busbar.
B. Outgoer labels should be provided next to the branch circuit breakers for easy and direct outgoers identification
PART 3 - EXECUTION
3.01 WORKMANSHIP & INSTALLATION
A. Materials, products and equipment furnished by the contractor, shall be installed and all work shall be performed in a first-class workmanship manner, in conformity with the best trade practices and the printed directions of the applicable manufacturers; by skilled workers equipped to produce satisfactory results; in a safe, substantial manner so as to avoid undue stresses, rigid enough to prevent undue movement, so as to present a neat, orderly appearance and to facilitate operating, servicing, maintenance and repairing.
B. All electrical equipment shall be installed in accordance with the manufacturer's recommendations, good electrical engineering practice, and the relevant drawings and specifications.
3.02 EQUIPMENT TESTING AND COMMISSIONING
A. After the installation is complete and properly adjusted, the contractor shall conduct operating tests. The various equipment and systems shall be demonstrated to operate in accordance with the requirements of the contract documents. Tests shall be performed in the presence of the client/client representative. The contractor shall provide electric power, instruments and personnel necessary for performing the various tests.
B. The testing of all electrical equipment shall include, but not be limited to, the items below. This shall be in addition to testing specified elsewhere in this specification.
a) General equipment check.
b) Field wiring and ground system verification.
c) Equipment adjustment.
1.01 DESCRIPTION
A. This section covers the manufacture, furnish, installation and testing of all equipment, accessories and materials required for the installation of LV Final Distribution Boards rated upto 250 Amps.
1.02 APPLICABLE CODES AND STANDARDS
A. The work shall be carried out in accordance with this specification, the contract drawings and the standards listed hereunder.
The following codes and standards provide an acceptable level of quality for materials and products:
1. SASO 1611 Saudi Standard for Low Voltage Distribution Boards
2. IEC 60439-3 Low voltage Final Distribution Boards.
3. IEC 60529 Degree of Protection provided by the encloure (IP Code)
4. IEC 60947-2 Low Voltage Switchgear and Controlgear – Circuit breakers.
5. IEC 61008-1 Residual Current operated Circuit Breakers without integral Overcurrent Protection (RCCB’s)
6. IEC 61009 Residual Current operated Circuit Breakers with integral
Overcurrent Protection. (RCBO)
1.03 QUALITY ASSURANCE
A. All materials and products shall be new, sound and uniform in quality, size, shape, color and texture and shall be free from defects.
B. The contractor shall be responsible for ensuring that the required standards of quality control as mentioned in relative sections are maintained for the proposed Distribution Boards.
C. The supplier shall provide proof of application of a quality procedure in the manufacturing facility complying with standards. This means:
1. use of a quality manual approved and signed by a management representative,
2. regular updating of this manual so that it reflects the most recent applicable quality control procedures,
3. ISO 9002 certification.
PART 2 - PRODUCTION
2.01 GENERAL
A. These specifications apply to LV Final Distribution Boards rated upto 250 Amps.
B. The Distribution Board and the associated Switchgear and Controlgear like Circuit Breakers, Contactors, Switches, etc. should be from the same manufacturer.
2.02 TECHNICAL CHARACTERISTICS
A. The Distribution Boards shall be designed and tested for the following electrical values:
1. Rated Insulation Voltage 690 V AC.
2. Rated Operating Voltage 415 V AC.
3. Frequency 50/60 Hz.
4. Busbar rated current upto 250 Amps. (or as indicated on the drawings)
5. Short-time withstand current 17 kA RMS for 200ms.
6. Peak Short Time withstand 34 kA
7. Degree of protection (IP) IP31 as per IEC 60529
2.03 CONSTRUCTION AND OPERATION
A. Metal enclosure of the low-voltage distribution board shall be made of electro galvanised steel sheet metal without any welding Points which shall have received an anti-corrosion coating (hot polymerised polyester/epoxy powder).
B. One central slotted hole should be provided to ease accurate levelling of the distribution board.
C. Additional slotted holes for ease at wall fixing should be provided.
D. The front face of the switchboards shall be removable to facilitate servicing.
E. Removable gland plate should be available at the top and the bottom of the distribution board
F. Cable knockouts should be available on sides, top and bottom of the distribution board for quicker and easier installation.
G. Main busbar should be made of tin-plated copper and fully shrouded.
H. Main busbar, in vertical position, should be installed into a rigid and adjustable suspended pan assembly.
I. In order to provide easy connection and maximum cable space, split neutral bars should be provided as standard in both sides.
J. Earth bar should be provided as standard.
K. Number of holes per terminal bar should not be less than the number of outgoings.
L. Switchgear and controlgear should be of DIN installation type.
M. Switchgear and controlgear connections to the busbar should be of bolt-on type.
2.04 PROTECTION AND SAFETY
A. The main busbar of the Distribution Board should be fully shrouded to prevent any accidental direct contact.
B. The split neutral busbar should be completely shrouded to prevent any accidental direct contact.
C. The Main Incoming Circuit-Breakers should provide additional Earth Leakage Protection. All the protection features of the Main Circuit Breaker, including Earth Leakage Protection, should be in full discrimination with those of the outgoing feeders (as per the relevant clauses of IEC 60947-2, IEC 61008 and IEC 61009) to minimise the isolation of a faulty part of the network.
D. All outgoing feeders to bathrooms, socket-outlets, AC units and Heaters should be provided with Residual Current Protection Devices for protection against direct and indirect contact, which should be coordinated with the Earth Protection of the Main Incoming Circuit Breaker.
E. All incoming switchgears should be suitable for isolation as per IEC 60947-2.
F. For critical loads requiring Continuity of Supply, all outgoing Branch Circuit-Breakers should be connected to the Main Bus bar by a fully shrouded OFF-LOAD Isolating Switch which should facilitate the replacement or removal of this Branch Breaker without de-energisation of the Distribution Board or any of the other adjacent Branches, and also provide complete protection against a direct contact with any energised part of the Distribution Board.
G. Keylock facility should be available in order to prevent the opening of the distribution board by non authorized persons.
H. Keylock should be field installable.
2.05 INDICATION
A. Identification labels should be provided for incoming and outgoing circuits, earth and neutral busbar.
B. Outgoer labels should be provided next to the branch circuit breakers for easy and direct outgoers identification
PART 3 - EXECUTION
3.01 WORKMANSHIP & INSTALLATION
A. Materials, products and equipment furnished by the contractor, shall be installed and all work shall be performed in a first-class workmanship manner, in conformity with the best trade practices and the printed directions of the applicable manufacturers; by skilled workers equipped to produce satisfactory results; in a safe, substantial manner so as to avoid undue stresses, rigid enough to prevent undue movement, so as to present a neat, orderly appearance and to facilitate operating, servicing, maintenance and repairing.
B. All electrical equipment shall be installed in accordance with the manufacturer's recommendations, good electrical engineering practice, and the relevant drawings and specifications.
3.02 EQUIPMENT TESTING AND COMMISSIONING
A. After the installation is complete and properly adjusted, the contractor shall conduct operating tests. The various equipment and systems shall be demonstrated to operate in accordance with the requirements of the contract documents. Tests shall be performed in the presence of the client/client representative. The contractor shall provide electric power, instruments and personnel necessary for performing the various tests.
B. The testing of all electrical equipment shall include, but not be limited to, the items below. This shall be in addition to testing specified elsewhere in this specification.
a) General equipment check.
b) Field wiring and ground system verification.
c) Equipment adjustment.
LV Air Circuit Breakers – (Typical Specifications)
1. General
(a) LV Air circuit breakers shall comply with standards IEC 60 947-1 and 2 or standards derived from the latter.
(b) The Air circuit breakers shall have a breaking capacity justified by calculations taking into account their installation location.
(c) The number of circuit-breaker poles shall be as indicated on the single-line diagram.
(d) The Air Circuit Breaker should be available from 800 Amps to 4000 Amps in only one Frame size.
2. Construction
2.1. General
(a) Circuit breakers shall be designed in such a way that maintenance may be carried out as a function of their use. To reduce maintenance, electrical endurance shall be greater than 12 500 cycles up to 1600 A, 10 000 cycles up to 4000 A and 5000 cycles for values greater than 4000 A.
(b) No safety clearance shall be required around drawout circuit breakers. For fixed circuit breakers, 150 mm of free space shall be provided above the arc chutes to allow removal of the latter.
(c) The operating mechanism shall be of the Open/Closed/Open stored-energy type. The closing time shall be less than or equal to 70 milliseconds.
2.2. Main contacts
(a) The main contacts shall be designed such that no maintenance shall be required under normal conditions of use.
(b) The main contacts shall be equipped with a visual wear indicator that may be accessed by removing the arc chutes, for immediate assessment of contact wear without requiring measurements or specific tools.
2.3. Arc chutes
(a) The arc chutes shall be removable on site.
(b) They shall be equipped with metal filters to reduce effects perceptible from the outside during current interruption.
2.4. Connection/disconnection mechanism
(a) It shall be possible to disconnect the circuit breaker without having to open the door. The three possible positions (connected, disconnected and test) shall be indicated.
(b) Before carrying out a disconnection or connection operation, the operator shall be required to press a release button located on the front of the chassis.
(c) The door shall be equipped with a locking system preventing door opening with circuit breaker in the connected position. Safety shutters shall be placed over the main incoming and outgoing circuits. A mismatch-prevention system shall block insertion of a drawout circuit breaker with a power rating greater than that of the fixed part.
2.6. Electrical auxiliaries
(a) All electrical auxiliaries, including the spring-charging gear motor, shall be installable on site without requiring adjustments or any tools other than a screwdriver.
(b) The auxiliaries shall be placed in a compartment which, under normal operating conditions, shall not contain any conducting parts capable of entering into electrical contact with the circuit-breaker poles. It shall be possible to connect all auxiliary wiring from the front of the circuit breaker.
2.7. Mechanical indicators
Mechanical indicators on the front panel of the power circuit breakers shall indicate the following status conditions:
1. "ON" (main contacts closed) Spring charged
2. "ON" (main contacts closed) Spring discharged
3. "OFF" (main contacts open) Spring charged – circuit breaker ready to close
4. "OFF" (main contacts open) Spring charged – circuit breaker not ready to close
5. "OFF" (main contacts open) Spring discharged
3. Protection / Control unit
3.1. General
(a) The control unit shall be interchangeable on site for adaptation to changes in the installation.
(b) Sensors shall be non-magnetic or of the Rogosky type for accurate current measurements.
(c) The control unit shall measure the true rms value of the current.
(d) The control unit shall comprise a thermal memory to store temperature-rise data in the event of repeated overloads or earth faults.
3.2. Protection
The control unit shall offer the following protection functions as standard:
(a) Long-time (LT) protection with an adjustable current setting and time delay;
(b) Short-time (ST) protection with an adjustable pick-up and time delay;
(c) Instantaneous (INST) protection with an adjustable pick-up and an OFF position.
(d) Current and time-delay settings shall be indicated in amperes and seconds respectively on a digital display.
(e) Earth-fault protection with an adjustable pick-up and time delay shall be provided if indicated on the appended single-line diagram.
3.3. Measurements
(a) An ammeter with a digital display shall indicate the true rms values of the currents for each phase.
(b) A LED bargraph shall simultaneously display the load level on the three phases.
(c) A maximeter shall store in memory and display the maximum current value observed since the last reset. The data shall continue to be stored and displayed even after opening of the circuit breaker.
3.3 Power measurements
(a) The control unit shall measure voltages and calculate power and energy values.
(b) These values shall be displayable on the screen and updated every second. The minimum and maximum values shall be stored in memory.
(c) Accuracy
Energy (kWh) 2.5%
Real power (kW) 2.5%
Apparent power (kVA) 2.5%
Demand power (kWh) 2.5%
3.4Measurement of power quality
The control unit shall offer functions allowing the analysis of the quality of AC distribution system power, including:
Measurement of the amplitude and phase of current and voltage harmonics up to the 50th order;
Measurement of the fundamental components of the voltage, current, active power, reactive power and apparent power;
Measurement of total current and voltage harmonic distortion.
3.5 Additional protection functions
The control unit shall offer the protection functions listed below.
Threshold Time delay
Minimum voltage
Maximum voltage
Voltage imbalance 25 to 690 V
100 to 931 V
10 to 90% Umean 0.5 to 3s
0.25 to 1 s
1 to 15 s
Minimum frequency
Maximum frequency 33 to 400 Hz
33 to 540 Hz 0.5 to 3 s
0.25 to 1 s
Current imbalance
Maximum current 5 to 90% Imax
0.4 In to Isd 1 to 15 s
0.5 to 1000 s
Phase sequence * 1/2/3
Instantaneous
Reverse power 2 to 20% of Pn 0 to 20 s
3.6 Communication
The circuit breaker shall be capable of communicating the following data via a bus:
Circuit-breaker status (open/closed, connected/disconnected/test, tripped on a fault, ready to close);
Control-unit settings;
Tripping causes;
The measurements processed by the control unit: current, voltage, frequency, power, power quality.
It shall be possible to remotely control the circuit breaker.
It shall be possible to remotely modify circuit-breaker settings:
Settings within the range defined by the switches on the front panel of the control unit;
Settings of the protection functions and the alarms.
Communications functions shall be independent of the control unit.
3.7Maintenance
The last ten trips and alarms shall be stored in two registers that may be consulted locally (date and time, type of fault or alarm).
Maintenance indicators shall be displayable on request on the front panel:
Percent wear of contacts;
Operations counter.
4.End of service life
The manufacturer shall provide instructions on the removal, dismantling and processing of circuit-breaker materials at the end of service life (material composition, weight, toxicity).
(a) LV Air circuit breakers shall comply with standards IEC 60 947-1 and 2 or standards derived from the latter.
(b) The Air circuit breakers shall have a breaking capacity justified by calculations taking into account their installation location.
(c) The number of circuit-breaker poles shall be as indicated on the single-line diagram.
(d) The Air Circuit Breaker should be available from 800 Amps to 4000 Amps in only one Frame size.
2. Construction
2.1. General
(a) Circuit breakers shall be designed in such a way that maintenance may be carried out as a function of their use. To reduce maintenance, electrical endurance shall be greater than 12 500 cycles up to 1600 A, 10 000 cycles up to 4000 A and 5000 cycles for values greater than 4000 A.
(b) No safety clearance shall be required around drawout circuit breakers. For fixed circuit breakers, 150 mm of free space shall be provided above the arc chutes to allow removal of the latter.
(c) The operating mechanism shall be of the Open/Closed/Open stored-energy type. The closing time shall be less than or equal to 70 milliseconds.
2.2. Main contacts
(a) The main contacts shall be designed such that no maintenance shall be required under normal conditions of use.
(b) The main contacts shall be equipped with a visual wear indicator that may be accessed by removing the arc chutes, for immediate assessment of contact wear without requiring measurements or specific tools.
2.3. Arc chutes
(a) The arc chutes shall be removable on site.
(b) They shall be equipped with metal filters to reduce effects perceptible from the outside during current interruption.
2.4. Connection/disconnection mechanism
(a) It shall be possible to disconnect the circuit breaker without having to open the door. The three possible positions (connected, disconnected and test) shall be indicated.
(b) Before carrying out a disconnection or connection operation, the operator shall be required to press a release button located on the front of the chassis.
(c) The door shall be equipped with a locking system preventing door opening with circuit breaker in the connected position. Safety shutters shall be placed over the main incoming and outgoing circuits. A mismatch-prevention system shall block insertion of a drawout circuit breaker with a power rating greater than that of the fixed part.
2.6. Electrical auxiliaries
(a) All electrical auxiliaries, including the spring-charging gear motor, shall be installable on site without requiring adjustments or any tools other than a screwdriver.
(b) The auxiliaries shall be placed in a compartment which, under normal operating conditions, shall not contain any conducting parts capable of entering into electrical contact with the circuit-breaker poles. It shall be possible to connect all auxiliary wiring from the front of the circuit breaker.
2.7. Mechanical indicators
Mechanical indicators on the front panel of the power circuit breakers shall indicate the following status conditions:
1. "ON" (main contacts closed) Spring charged
2. "ON" (main contacts closed) Spring discharged
3. "OFF" (main contacts open) Spring charged – circuit breaker ready to close
4. "OFF" (main contacts open) Spring charged – circuit breaker not ready to close
5. "OFF" (main contacts open) Spring discharged
3. Protection / Control unit
3.1. General
(a) The control unit shall be interchangeable on site for adaptation to changes in the installation.
(b) Sensors shall be non-magnetic or of the Rogosky type for accurate current measurements.
(c) The control unit shall measure the true rms value of the current.
(d) The control unit shall comprise a thermal memory to store temperature-rise data in the event of repeated overloads or earth faults.
3.2. Protection
The control unit shall offer the following protection functions as standard:
(a) Long-time (LT) protection with an adjustable current setting and time delay;
(b) Short-time (ST) protection with an adjustable pick-up and time delay;
(c) Instantaneous (INST) protection with an adjustable pick-up and an OFF position.
(d) Current and time-delay settings shall be indicated in amperes and seconds respectively on a digital display.
(e) Earth-fault protection with an adjustable pick-up and time delay shall be provided if indicated on the appended single-line diagram.
3.3. Measurements
(a) An ammeter with a digital display shall indicate the true rms values of the currents for each phase.
(b) A LED bargraph shall simultaneously display the load level on the three phases.
(c) A maximeter shall store in memory and display the maximum current value observed since the last reset. The data shall continue to be stored and displayed even after opening of the circuit breaker.
3.3 Power measurements
(a) The control unit shall measure voltages and calculate power and energy values.
(b) These values shall be displayable on the screen and updated every second. The minimum and maximum values shall be stored in memory.
(c) Accuracy
Energy (kWh) 2.5%
Real power (kW) 2.5%
Apparent power (kVA) 2.5%
Demand power (kWh) 2.5%
3.4Measurement of power quality
The control unit shall offer functions allowing the analysis of the quality of AC distribution system power, including:
Measurement of the amplitude and phase of current and voltage harmonics up to the 50th order;
Measurement of the fundamental components of the voltage, current, active power, reactive power and apparent power;
Measurement of total current and voltage harmonic distortion.
3.5 Additional protection functions
The control unit shall offer the protection functions listed below.
Threshold Time delay
Minimum voltage
Maximum voltage
Voltage imbalance 25 to 690 V
100 to 931 V
10 to 90% Umean 0.5 to 3s
0.25 to 1 s
1 to 15 s
Minimum frequency
Maximum frequency 33 to 400 Hz
33 to 540 Hz 0.5 to 3 s
0.25 to 1 s
Current imbalance
Maximum current 5 to 90% Imax
0.4 In to Isd 1 to 15 s
0.5 to 1000 s
Phase sequence * 1/2/3
Instantaneous
Reverse power 2 to 20% of Pn 0 to 20 s
3.6 Communication
The circuit breaker shall be capable of communicating the following data via a bus:
Circuit-breaker status (open/closed, connected/disconnected/test, tripped on a fault, ready to close);
Control-unit settings;
Tripping causes;
The measurements processed by the control unit: current, voltage, frequency, power, power quality.
It shall be possible to remotely control the circuit breaker.
It shall be possible to remotely modify circuit-breaker settings:
Settings within the range defined by the switches on the front panel of the control unit;
Settings of the protection functions and the alarms.
Communications functions shall be independent of the control unit.
3.7Maintenance
The last ten trips and alarms shall be stored in two registers that may be consulted locally (date and time, type of fault or alarm).
Maintenance indicators shall be displayable on request on the front panel:
Percent wear of contacts;
Operations counter.
4.End of service life
The manufacturer shall provide instructions on the removal, dismantling and processing of circuit-breaker materials at the end of service life (material composition, weight, toxicity).
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