Electrical Specification.doc

7/25/2019 Electrical Specification.doc

1/26

SPECIFICATION FOR ELECTRICAL WORKS


2/26

TABLE OF CONTENT

1.0 GENERAL SPECIFICATIONS..............................................................................1

1.1 Scope....................................................................................................................................11.2 Rates....................................................................................................................................1

1.3 Quat!t!es............................................................................................................................1

1." #$a%!&s.............................................................................................................................1

1.' Cutt!&( Patc)!& A* Repa!$!&......................................................................................2

1.+ E,u!p-et P$otect!o........................................................................................................2

1. Ise$ts A* S/eees.............................................................................................................2

1. C/ea!&..............................................................................................................................2

1. Ope$at!o............................................................................................................................2

1.10 Gua$atee.........................................................................................................................2

1.11 E,u!p-et Coect!os...................................................................................................3

1.12 Saet4 A* #!scoect S%!tc)es......................................................................................3

1.13 Co*es( Ru/es( A* Re&u/at!os........................................................................................3

2.0 TEC5NICAL SPECIFICATIONS........................................................................."

2.1 Po%e$ Supp/4......................................................................................................................"2.1.1 Lt Power Supply........................................................................................................................ .........4

2.1.2 Ht Power Supply.................................................................................................................................4

2.2 Fee*e$ P!//a$........................................................................................................................"2.2.1 General................................................................................................................................................4

2.2.2 Construction........................................................................................................................................4

2.2.3 Switch Fuses................................................................................................................................. ......4

2.2.4 Miniature Circuit Breaker MCB!.................................................................................................... ..4

2.2." Moul#e# Case Circuit Breaker MCCB!............................................................................................42.2.$ %ir Circuit Breaker %CB !................................................................................................................"

2.2.& Bus'ars................................................................................................................................. ......... ....."

2.3 Fus!& A* Spa$e Fuses.....................................................................................................'

2." G$ou*!& 6Ea$t)!&7........................................................................................................'2.4.1 General................................................................................................................................................"

2.4.2 (arthin) Set........................................................................................................................... .......... ..."

2.4.3 Pro*isions..................................................................................................................................... ......$

2.4.4 Li)htnin) Protection Syste+......................................................................................................... .....$

2.4." (lectrical (,uip+ent Protection..................................................................................................... ....$

2.4.$ Buil#in) Protection.............................................................................................................................$

2.' Stee/ Tu8u/a$ Po/es.............................................................................................................+2.".1 Poles -or alkway li)htin).................................................................................................................$

2.".2 Poles -or %rea li)htin)..................................................................................................................... ...&

2.".3 Poles -or L/ 0*erhea# lines........................................................................................................ ......&

2.".4 Poles -or H/ 0*erhea# lines...............................................................................................................&

2."." Pole Stay......................................................................................................................................... ....&

2.".$ House Ser*ice Cla+p........................................................................................................... ......... .....&

2.+ 9a!s A* Su8:9a!s Pc Isu/ate* A$-ou$e* Ca8/es.................................................

2. Ca8/e La4!& ; Oe$)ea* #!st$!8ut!o


3/26

2. W!$!& Ca8/e Ru =*e$ #e!e* Co*!t!os..................................................................2..1 Multi:Core Ca'le............................................................................................................................... .9

2..2 Pro*ision -or Ma;i+u+ Loa#...................................................................................................... ......9

2..3 Selection o- Sie o- Con#uctor........................................................................................................ ...9

2..4 Ca'le (n#s....................................................................................................................................... ...9

2.." Passin) /hrou)h alls %n# Floors.....................................................................................................9

2. Lt S%!tc) Gea$s................................................................................................................102.9.1 Main Switch Boar#........................................................................................................................ ...1-;c. witch gear busbars - & ?;)-?d. 07C fuse links-& :@-e. Aistribution fuse boards-& >;)->f. nclosure for low voltage switch gear-&


7/26

o. 2G0 meters - & - ; F p. /. B. &solators - & >:; F ;q. /. B. +ir Circuit $reakers - & ) F )r. Hiniature Circuit $reakers - DHC$E - & @@@ F


8/26

2.0 TEC5NICAL SPECIFICATIONS

2.1 Po%e$ Supp/4

2.1.1 Lt Po%e$ Supp/4The electrical power system shall be of +C three phase ! single phase with9::!?< volt, ): hert1 system. Three phase system shall be ?-phase, 9-wire withneutral solidly earthed.

2.1.2 5t Po%e$ Supp/4The high voltage power supply shall be of +C three phase


9/26

receive link or cable shoes used for +/C4KA cables. The terminals shall beequipped with insulating barriers to avoid inter-phase arcing. The operatinghandle shall give denite trip indication by positioning the operating handle inbetween 4K and 488 positions. The resetting of trip mechanism shall be done bypushing the handle to 488 position prior to re-closing. The HCC$ shall beequipped with silver alloy contacts with wipe action movement during operation.

The contacts shall be provided with individual arc chutes to draw away the arcfrom the contact tips to quench the arc. The HCC$ shall be equipped with bi-metallic strip for overload protection with inverse characteristic and magnetic coilfor short circuit protection. The HCC$ shall be suitable to interrupt short circuitfault current range of


10/26

2." G$ou*!& 6Ea$t)!&7

2.".1 Gee$a/The grounded neutral of the secondary distribution system shall be supplementedby an equipment grounding system to safeguard equipment and personnelproperly. quipment grounding system shall be incorporated to all metallic

enclosures, cabinets and other conductive items in close proximity with electricalcircuits and shall operate continuously at ground potential and shall provide a lowimpedance path for possible ground fault currents. The system shall comply with& M $ specications.

2.".2 Ea$t)!& Set

The earthing set as per & M $ should consist of the following or as detailed in thebill of quantities.

a. < no. >: cm x >: cm x :.? cm - copper plateb. < no. mm copper strips or bare copper wire of

appropriate gauge, as the case may be, as stated in the $J.

2.".3 P$o!s!oseparate earthing station with complete earthing set as mentioned above shall beprovided for each of the following

a. 8eeder 3illars, Hain switch board, distribution boards, transformer body, etc.

b. /ightning +rresters for high voltage equipment.c. /ightning protection of the buildingd. Transformer neutrale. Ienerator neutral

NOTE :

The armour of the armoured cable shall be used as additional earthing conductoras far as practicable. The interconnection of earth stations shall be done as far aspracticable to reduce the earth resistance of the earth grid, and these inter-connection shall be done under ground only .The si1e of the inter-connectingconductor shall be not smaller than GI @ copper wire. The earth resistance shall,in no case exceed > ohm. Auring the connection and the burial of the earth

stations the presence and the approval of the representative from the client isobligatory.

2."." L!&)t!& P$otect!o S4ste-&n order to protect the high voltage electrical equipment, and the personnelagainst atmospheric lightning surges the incoming over-head lines and themetallic parts of the building should be e"ectively earthed with minimumimpedance, to discharge the surge prior to reaching surge voltage to theequipment or personnel to be protected.

2.".' E/ect$!ca/ E,u!p-et P$otect!o

The high voltage power cable connecting the end of incoming over-head line,distribution transformer connected directly to the over-head line or other end ofthe under ground cable and high voltage switch-gears are to be protected against

$


11/26

lightning surge voltage by means of lightning arresters with non-linearcharacteristics. These arresters will have to be install nearest to the equipment tobe protected, at the beginning end of insulated cable, or transformer connection.The arrester will be e"ective only if good earth with minimum impedance isconnected. The nearest earth terminal shall be connected to the lightningarresters. Care must be taken to see that the copper wire or strip used to connect

the earth station shall be as straight as possible without any loop and no metallicpipe shall be used as mechanical protection to the earth conductor. &f there is aneed to protect any portion of the earth connecting lead against mechanicaldamage non metallic pipe may be used.

2.".+ Bu!/*!& P$otect!oThe most e"ective way of protection of building against lightning surge is toinstall lightning rods with pointed tips erected at the highest points of thebuilding. The number of lightning rods and their distribution depends upon theheight and roof area of the building. +ll the lightning rods shall be interconnectedand connected to the nearest earth station by means of down copper conductorsof appropriate section. The down conductors shall be as short and straight as

possible avoiding unnecessary bends and loops to reduce the impedance to thelightning surge. The down conductor strip shall be clamped to the vertical wall bymeans of insulator blocks at an interval of one metre.

2.' Stee/ Tu8u/a$ Po/es

2.'.1 Po/es o$ Wa/%a4 /!&)t!&The pole shall be of galvanised ! painted steel of appropriate diameter and lengthas specied in the drawing or bill of quantities. &t should also have holes for cableentry and exit. The poles shall be planted to specied depth in accordance withthe height of the pole and the pole bottom shall be concreted by plain cementconcrete of ratio


12/26

lenght above ground level. The remaining ;: cm shall remain buried underground. The pole including cross arms shall be painted by two coats of red oxidepaint.

2.'." Po/es o$ 5T Oe$)ea* /!es

The poles to be used shall be mt long DcompleteE consisting of three sectionof di"erent si1ed H pipes welded together with at least : cm of overlap at the'oints. The dimensions of each section of the pole shall be as follows

Pole Section Outside dia. Length ThicknessTop section


13/26

2.+ 9a!s A* Su8:9a!s Pc Isu/ate* A$-ou$e* Ca8/es

These shall conform to /atest &!$!CH pecications and shall be of plaincircular ! sector shaped stranded +luminium ! Copper conductor with si1e andcolour as mentioned in the $ill of Juantities.

2. Ca8/e La4!& ; Oe$)ea* #!st$!8ut!o!-u- Loa*+ll conductors, switches and accessories shall be of such si1e as to be capable ofcarrying, without their respective ratings being exceeded, maximum currentwhich will normally Now through them.

2..3 Se/ect!o o S!De o Co*ucto$The si1es of conductors of circuits shall be so selected that the drop in voltagefrom consumers# terminals in a public supply to any and every point on theinstallation does not exceed three percent of voltage at the consumer#s terminalswhen the conductors are carrying the maximum current under the normalconditions of service.

&f the cable si1e is increased to avoid voltage drop in the circuit, the rating of thecable shall be the current which the circuit is designed to carry. &n each circuit orsub-circuit every cable shall have a current rating not less than that of the currentrating of the respective protection gear.

1


15/26

2.." Ca8/e E*stranded Conductors having a nominal cross-sectional area exceeding > sq. mmshall always be provided with cable lugs and crimping method suitably applied.

Ghen a stranded conductor having a nominal cross-sectional area less than > sq.mm is not provided with cable socket, all strands at the exposed end of the cable

shall be soldered together. +nti oxide grease shall be provided on the exposedend conductor after soldering.

&n any system of wiring, no bare or twist 'oints shall be made at intermediatepoints in the through run of cables unless the length of a nal sub-circuit, sub-main or main is more than the length of the standard coil as given by themanufacturer of the cable. &f any 'oint shall be made through proper cut-outs orthrough proper 'unction boxes they shall be easily accessible for inspection.

2..' Pass!& T)$ou&) Wa//s A* F/oo$sGhere conductors pass through walls, one of the following methods shall beemployed. Care shall be taken to see that wire pass freely through protective pipe

or box and that wire pass through in a straight line without any twist or cross inwires on either ends of such holes.

The conductor shall be carried either in a rigid steel conduit conforming toaccepted standards or a rigid or semi-rigid non-metallic conduit conforming toaccepted standards.

2. Lt S%!tc) Gea$s

2..1 9a! S%!tc) Boa$*The main switch board shall be in door type, totally enclosed, mild steel sheetmetal of GI clad, front standing and shall be dust and vermin proof. The

design shall be xed on a modular construction, the fused switch ! HCC$ ! HC$feeder units being arranged in multi-tier formation in hori1ontal ! vertical panels,fed from hori1ontal ! vertical busbars. The ratings of each feeder and their orderincluding other ancillary gears to be equipped with will be as detailed in the bill ofquantity.

i. +ll cabling and maintenance shall be carried out from front and the unit shallbe extensible feeder control units arranged in individual compartments withhinged doors. +ll feeder control units shall be front operated. +d'oining surfaceof doors and covers shall be gasketed.

ii. $usbars shall be of high conductivity copper bar of su5cient cross sectionalarea so that a current density of ?) amp. per sq.cm is not exceeded at

normal current rating and supported on non-hygroscopic insulator. The neutralbusbar cross section shall be not less than ):L of the phase busbars. Theearth bar cross section shall not be less than )L of the phase busbars.

iii. Clamp type terminals for copper cables may be provided for feeders up to ?:amp. 8or feeder of higher rating suitable cable lugs shall be used.

iv. The feeder control units ratings shall be as specied in the drawing or bill ofquantity, switches shall be of quick make and break design with double breakper pole. witch contacts shall be silver plated and housed in suitableinsulator. The feeder control operating handle shall be mounted on the frontcover.

11


16/26

2..2 #!st$!8ut!o Boa$*Aistribution board shall consist of fused switch ! HCC$ ! HC$ of ratings as detailedin the drawing or bill of quantities. &t should be factory assembled, Nush mountedtype, of mild steel cabinets, having dead front with hinged door, Nush locks, and atypewritten card directory on the door identifying each circuit. The A$ box shall benished with grey enamel paint on all sides. $ranch circuit breakers used for

various circuits shall be mounted in a group at the suitable location of the board.The outgoing circuit breakers shall be quick make and break type equipped withoverload thermal and short circuit magnetic tripping protection.

Mounting The board shall be mounted with the top of the cabinet > feet, >inches above the nished Noor unless otherwise noted in the drawings or bill ofquantity. The cabinet shall be plumb and square with the wall of the structure.

12


17/26

2.10 Fee*e$ W!$es A* Ca8/es

2.10.1 Sta*a$*s+ll wires and cable for feeder circuits shall be as per latest & ! $ ! CH+ ! Kspecications.

2.10.2 W!$e A* Ca8/e P$otect!ouitably protect wires and cables from weather and damage during storage andhandling item shall be in rst class condition when installed.

2.10.3 W!$e a* Ca8/e Ista//at!o

i. Conductors si1es shall be standard metric or $ritish wire gau1e. Conductorsshall be stranded and shall have colour coded phase wires. Keutral used for?:B circuits shall have a distinguished colour tracer. Cables installed inconduits shall be single core un-armoured and colour coded as per & wiresi1e, insulation, and manufacturer#s name shall be permanently marked on

conductor 'acket.

ii. Circuit conductors shall extend to the outlets shown. Circuiting basically shallbe as shown in the drawings provided. +n arrow indicating to distributionboard is a complete circuit i.e. consisting of - one phase conductor, oneneutral conductor and one earthing conductor wires with colour codes, in asuitable conduit and wire si1es of all should be same as per the outletsloading. 7equest for deviations in methods of circuiting and conduit branchcircuit distribution shall be submitted in shop drawings form for approval.

2.11 W!$!&s

2.11.1 Gee$a/Giring of nal circuits for lights, convenience outlets, fans, call bell, etc., shall becarried out by distributions and looping system as shown in the drawings. The si1eof phase wires shall not be less than amp. convenience outlets


18/26

14


19/26

2.12 Co*u!t!&

a. +ll wiring shall be drawn inside 3BC conduits and in concealed manner, unlessotherwise shown. The smallest si1e of the conduit used shall be mm dia.and mm thick. The si1e of the conduit to be used in any section depends

upon the number and si1es of the cable to be drawn in that particular section.+s a general rule the sum total area of the cables shall not exceed >: L ofthe internal sectional area of the conduit.

b. Ghere no si1e is shown for conduit for the conductors indicated, use theminimum code-permitted si1e. 3rovide si1es in excess of code requirementswhere more bends are encountered.

c. 3rotect conduits from entry of foreign materials during construction, replaceconduits containing any foreign materials that can not be removed, clean outconduit containing water before conductors pulled in.

d. Conduits shall run in a direct line with long sweep bends and o"sets. HetallicConduits shall be continuous and secured to boxes with glands termination tomaintain electrical continuity.

Conduits Crossing 4ver xpansion Points 3rovide minimum ?: cm lengthNexible conduit at the point of crossing building expansion 'oints. xtraconduits and cables shall be provided at the expansion 'oints for minimum


20/26

2.13.2 Wa// B$acet a* Ce!/!& Bo>es$oxes for lighting xtures outlets at wall bracket and ceiling surface mountedlocations shall be not less than >.) mm dia. and of appropriate depth.

2.13.3 uct!o Bo>es

Punction $oxes for branch circuits shall be not less than


21/26

deemed excessively noisy by the Consultant shall be replaced, without anyadditional cost.

g. 8ixture diameters and si1es shall be as specied in $ill of Juantities or asapproved.

h. /eave xtures clean at the time of nal completion of work every item shallbe in proper working order. 3rotect xtures as required from dirt, dust, paint,debris, etc.

i. 3rovides all Nuorescent xtures with power factor improvement capacitors.

'. Berify, ceiling construction, recessing depth, and other constructional detailsprior to installation. 3rovide plaster frame for all xtures recessed in plasterceilings.

2.1+ #!st$!8ut!o T$aso$-e$

2.1+.1 Re,u!$e-etCopper wound


22/26

a. 4" load tap changer with locking arrangement.b. ilica gel breatherc. 4il conservator with oil level indicatord. /ifting lugs.e. teel rollers

f. Tank grounding terminalsg. Arain valve with plug on the bottom of the tank.

2.1 5!&) ?o/ta&e S%!tc) Boa$*

a. The switch board shall be in general line with & ) (?* rated to ): HB+Dminimum fault levelE at


23/26

2.1 Sta*:B4 #!ese/ Gee$ato$ Set

The details of the diesel generator set including the capacity and the ancillaryequipment, ie indication, protection, alarm gears , etc. shall be as per the bill ofquantity or the addenda supplied along with this specication.

2.1 Co-p/et!o Tests

+fter completion of the electrical installation work, the following tests will becarried out on both the 0igh Boltage and /ow Boltage sides before the installationwork is made operational.

a. Tests related to all statutory regulations of the local supply authorities e.g.Kepal lectricity +uthority.

b. Hake tests as per &!$ specications and & code of practice to demonstratethat all equipment, accessories and connection thereto have been properlyinstalled, and the complete facility operates with its intended purpose and asper contract document.

c. Tests related to the specication and instructions of the manufacturers of the

equipment being installed.d. The insulation resistance of low voltage system and high voltage system shall

be measured separately to insure su5cient insulation resistance of eachsystem between the line conductor and earth prior to test charging. &n thecase of high voltage system insulation resistance is measured by applying )::volt dc supply. +fter the successful testing with ):: volt pressure further testvoltage of ):: volt dc shall be applied and the resulting insulation resistanceshall be measured. &n the case of low voltage system neutral conductorshall be isolated from earth prior to supplying ):: volt dc test voltage to allphases with all light switches and feeder switches closed, and insulationresistance shall be measured. The insulation resistance value of eachfeeder shall be such that it should not be less than ): divided by the numberof points connected to that particular feeder. The insulation resistance of thewhole installation , however, shall not be less than one mega ohm.

3rior to performing test on the completed works the consultant shall be notied inadvance. The contractor shall arrange all the instruments required for testing athis own cost.

The consultant may direct to perform additional test other than the scheduledtests to conrm the quality of materials used and workmanship of completedworks.

hould any defects discovered or arise during testing the contractor shallpromptly correct those defects including any modication, if necessary, to avoid

such premature defects arising in the future, and get test certicate from theconsultant prior to nal approval of the completed works.

2.20 Ot)e$ Spec!!cat!os @I B$!e

a. Ghen quoting for various items listed in the $ill of Juantities specic mentionmust be made of what make of goods will be supplied ! installed. +ll quoteditems should be products of reputable ! recognised manufacturers.

b. +ll the A$s will have an in-comer isolator or fuse switch or HC$ or HCC$ asdetailed in the $J and drawings. The sheet steel wall mounting A$ will havehinged and lockable door.

19


24/26

c. +ll control units including A$s will have continuous earth connection to themain earth connector with GI-@ copper wire or copper tape of appropriatesi1es as detailed in the $J.

d. arthing will be as per && ?:9> (>*. Haximum earth resistance shall notexceed > ohm.

e. +ll main multi-core power cables to switch board ! A$ shall be rated at


25/26

lectrical &nspector from the Kepal lectricity +uthority or any other concernedauthority. The work shall not be deemed to have been completed until theabove certicate has been obtained by the Contractor.

21


26/26

L!st o app$oe* 9auactu$e$s o$ E/ect$!ca/ 9ate$!a/s

. /. T. 0ouse wiring cables Kepal Gires and Cables Trishakti Cables, 3ioneerlectro cables

;. Hain witch $oard 8abrication 0yon'an lectrical $ala'u lectro /td Coronalectrical ngineering or equivalent

@. Aistribution $oard 8abrication 0yon'an lectrical $ala'u lectro Crabtree0avells,Corona lectrical ngineering or equivalent

=. Houlded Case Circuit $reaker Herlin Ierin I. 0avells nglish lectric CoDHCC$E iemens or equivalent

Electrical Specification.doc

Documents

Transcript of Electrical Specification.doc