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I S 1646: 1997

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CODE OF PRACTICE FORSAFETY OF BUILDINGS (GENERAL):ELECTRICAL INSTALLATIONS

( Second Rev i si on )

ICS 91.120;13.220.50

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Fire Safety Sectional Committee, CED 36

FOREWORDThis Indian Standard (Second Revision) was adopted by the Bureau of Indian Standards, after the draftfinalized by the Fire Safety Sectional Committee had been approved by the Civil Engineering DivisionCouncil.This standard was first published in 1961, revised subsequently in 1982. The present revision is based onthe subsequent development and modifications in other regulations such as electrical rules of the TariffAdvisory Committee, Indian Electricity Rules, etc, and other Indian Standards. Special precautionarymeasures for use of aluminium conductors and for use of fluorescent fittings in electrical installations areincluded in the revision. The other changes relate to the developments in wiring methods and othergeneral aspects.The requirements of this code are to be treated as supplementary to the requirements of the IndianElectricity Act, 1910 and the Rules of 1956 thereunder and in no case as substitutes. In the preparationof this code, it has been presumed that the electrical installation work is carried out by qualifiedcontractors and electricians under the supervision of competent engineers as required by the IndianElectricity Rules.For the purpose of deciding whether a particular requirement of this standard is complied with, thefinal value, observed or calculated, expressing the result of a test, shall be rounded off in accordance withIS 2 : 1960 Rules for rounding off numerical values (revised). The number of significant places retainedin the rounded off value should be the same as that of specified value in this standard.

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IS 1646 1997

I ndian St andardCODEOFPRACTICEFOR

FIRESAFETYOFBUILDINGS(GENERAL>ELECTRICALINSTALLATIONS

( econd Rev i si on )1 SCOPEThis standard covers recommendations relating tofire safety of electrical installations in buildings.2 REFERENCES2.1 The Indian Standards listed in Annex A containprovisions which, through reference in this text,constitute provisions of this standard. At the timeof publication, the editions indicated were valid.All standards are subject to revision, and parties toagreements based on this standard are encouragedto investigate the possibility of applying the mostrecent editions of the standards given in Annex A.3 GENERAL REQUIREMENTS3.1 Besides conforming to this Codeall equipmentshall comply with relevant Indian StandardSpecifications (wherever available) as regards con-struction, temperature rise, current rating, over-loads and performance, etc, where an IndianStandard does not exist the various items of electri-cal equipments should be those approved by thecompetent authority.3.2 Execution of work unless otherwise exemptedunder the appropriate rule of the Indian ElectricityRules, the work of electrical installations shall becarried out by an electrical contractor licensed andunder the direct supervision of a person holding acertificate of competency and by persons holding avalid permit issued and recognized by any IndianGovernment.3.3 All equipment shall be capable of developingand/or consuming the rated power safely and con-tinuously (unless specifically meant for intermitentuse), without undue heating, sparking, noise andvibration.3.4 All electrical equipment shall be securelymounted on the surface on which they are installed.3.5 All electrical equipment, fittings, accessoriesand wiring systems in locations which are exposedto the following shall be of types approved for

particular situations and subject to special condi-tions as laid down in the appropriate clauses of thiscode:a)b)

Fumes;Flammable or other gases, vapours or li-quids having deleterious effect on equip-ment and conductors or creating dangeroussituations;

c)d)e)

Dust and fibrous accumulations;Damp or wet locations; andExcessive temperature.

3.6 Manufacturers name, trade-mark or otherdescription markings by which the manufacturermay be identified shall be placed on all electricalequipment, accessories, electrical cables, etc.Other markings like voltage current and wattageshall also be provided as necessary. Marking shallbe of sufficient durability to withstand the environ-mental conditions.3.7 The type of wiring installed in a particularoccupancy shall be as permitted under the relevantprovisions of this standard.3.8 Where aluminium conductors are used in theelectrical installation, special precautionarymeasures as given in IS 732 shall be followed.4 POWER EQUIPMENT4.1 The term power equipment shall be deemed toinclude motors, motor-generators, control gears,switch gears, rotary convertors, rotary balancers,rotary condensers, phase advancers, frequencychangers and any other rotating electric equipment,rectifiers and inverters.4.2 All electrical equipment located in situationswhere:

a) The atmosphere is likely to contain flam-mable/explosive gases or vapours; and

b) Combustible dust, fluff or similar materialslike saw mills and other wood working oc-cupancies, cotton/jutebooden/viscose and

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IS 1646:1997acrylic, nylon 66 fibre mills, flour mill, pul-verising works, etc, shall comply with thespecial requirements in respect of Hazard-ous Location specified in 13.

4.3 Equipment which depends on natural air forcooling shall be so located and installed that airflow over the exposed cooling surface shall not beprevented by adjacent equipment or walls. Forfloor mounted equipment, clearance between topsurface of the equipment and the adjacent surfaceshall be provided to dissipate rising hot air.4.4 Equipment ventilating openings shall be soinstalled that no obstruction may prevent free aircirculation through them; nor shall any material bedumped or allowed to settle on them so as to clogthe ventilation openings or interfere in any waywith normal cooling of such equipment.4.5 All equipment of more than 114 kW shall beseparated from unprotected woodwork by a dis-tance of at least 300 mm horizontally and 1200 mmvertically. Equipment of l/4 kW or less, exceptthose of totally enclosed type, shall be suitablyguarded to avoid heat being transmitted to readilycombustible material in the vicinity.4.6 Equipment shall be periodically inspected andmaintained as per relevant Indian Standards bycompetent staff who shall keep complete records ofall such activities.4.7 The position of equipment shall be selectedwith due consideration of accessibility, main-tenance and overhaul.4.8 Equipment terminals shall be rigidly designedand planned according to size and type of machine.Industrial motors shall have a robust metal cladterminal box of adequate dimensions arranged toreceive armoured or vulcanized rubber insu-lated/PVC cables in conduits without unnecessarybends in the cables. All terminal boxes shall beentirely reptile, rodent and insect proof.5 SWITCHBOARDS5.1 Switchboards shall be erected in easily acces-sible and approved positions where cotton fluff,dust or dirt is not present. The switchboard shallbe located in dry locations.5.2 The space around the switchboards shall not beused for storing of clothing or other materials, evenfor temporary period.5.3 Each outgoing circuit from the switchboardshall be separately controlled by a suitable auto-matic circuit breaker or linked switches and cut-outs. In case the electrical installation draws powerfrom a distribution transformer having a capacityof 150 BVA or more, the switches shall be provided

with HRC fuses at all fuse points, irrespective ofcurrent rating of the circuit. This, however, neednot be insisted in case of low tension installation.5.4 All switches and circuit breakers shall beoperated from the front of the switchboard.5.5 All fuses shall be mounted on the front of theswitchboard as far as practicable.5.6 All screws, bolts and nuts, which secure currentcarrying parts to the board shall be of brass, copperor similar rustproof material.5.7 All wires and cables shall be provided withsoldered or approved lugs or crimped joints or anyother approved means of connection.5.8 In situations where the atmosphere is likely tocontain explosive gases or vapour, switchboardsshall be of explosion protected type. Selection ofelectrical equipment shall be as per IS 5571 (seealso IS 5572 for classification of hazardous areas).Alternately pressurised air lock enclosures may beprovided for switchrooms. Wherever not possibleswitchroom should be themselves pressured.5.9 Where the switchboard is erected in a room ofa building isolated from the source of supply or ata distance from it, adequate means of control andisolation shall be provided both near the boards andat the origin of supply.5.10 All switchboard shall be of metal clad totallyenclosed type or any insulated enclosed patternwhich should be fixed at close proximity to the pointof entry of supply.5.11 In case of outgoing circuits from theswitchboard, where the current rating exceeds 63A,connection between the busbar chamber and theautomatic circuit breaker or switch fuse or anyother control gear shall be made only by solid con-nections.5.12 Timber shall not be used in construction of aswitchboard.5.13 All circuits shall be clearly and indeliblylabelled for identification in English and ver-nacular.5.14 Moulded case circuit breakers shall not bepermitted except inside a metal enclosure.5.15 The neutral of each main and branch maincircuit shall be provided with a removable linkplaced in an easily accessible position, for purposeof testing. The neutral shall not be punched at theback of the board.

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IS 1646 : 19976 POWER DISTRIBUTION AND MOTOR compartment but separated from each other byCONTROL GEAR more than 15 m.6.1 All equipment shall be of metal clad construc- 6.9 Outgoing circuits shall be clearly marked intion throughout, dust tight, suitably proportioned English and vernacular, indicating the departmentand of adequate capacity and shall conform to the or place or item controlled, by each.relevant Indian Standards. 6.10 All circuits shall be arranged symmetrically,6.2 Equipment shall be accessible at all times, as far as practicable.stacks of goods and the like shall not impede accessto any part of the equipment. 6.11 Each circuit from a main distribution boardshall be provided with a circuit breaker, linked6.3 Wiring to and from the gear shall be of the switches or cut-outs.armoured,.mineral insulated or screwed steel con-duit type and provision shall be made to secure the 6.12 Looping of conductors and tee joints in powersame by approved and efficient mechanical wiring shall be provided with a circuit breaker,methods. Flexible tubing shall not be accepted for linked switches or cut-outs.general wiring. It may, however, be used for con- 6.13 Detachable inspection covers shall benections between the terminal boxes of motors and provided to examine connections.

_tarters, switches and motors but the length shall berestricted to a maximum of 1 200 mm. 6.14 Woodwork shall not be permitted for mount-NOTE - Non-metallic conduits conforming to IS 9537 ing of or construction of frame work of any iron-(Part 3) may be used for mediumoltage installation, subject clad switch control or distribution gear.to following conditions:

a) The conduits should be supported not more than 800mm distance and should have suitable joints.

b) Separate earthing conductor shall be run inside theconduit for earthing the equipment to which the con-ductor is connected.

c) Gpansion joints shall be provided where required tocompensate for thermal expansion and contraction.

Such non-metallic conduit shall not however be allowed infollowing locations:

a) In locations less than 2.5 m above walking floor levelunless protected against mechanical damage.

b) Where ambient temperature is likely to be. above 55Cat some time or other during year.c) In concealed places of combustible construction.

d) In locations where the atmosphere is likely to containflammable gases or vapours.

e) In locations where the surrounding atmosphere is likelyto affect the non-metallic conduits.

6.4 The ends of all conduits shall be bushed.6.5 All unused cable holes shall be effectivelyclosed.6.6 All current carrying parts, namely terminals,washers and clips shall be of copper, brass or of anyother equally non-rusting material, properly tinnedat joints.6.7 All cables shall be provided with soldered lugsor other approved means for connection.6.8 Where a distribution board or group of dis-tribution boards is/are erected in a room of a build-ing isolated from the source of supply, adequatemeans of control and isolation shall be providedboth near the board and at the origin of supply.Similar means of control and isolation shall beprovided even if the source of supply and the dis-tribution board(s) is/are located inside the same

6.15 Motors shall not be connected to lighting dis-tribution boards.6.16 Suitable guard enclosures shall be provided toprotect exposed current carrying parts of motorsand insulations of motor leads where installeddirectly under equipment or in other locationswhere dripping or spraying of oil, water or otherinjurious liquids may occur, unless the motor isdesigned for such conditions.6.17 In situations where dust or flying materialsmay collect on or in motors in such quantities as toseriously interfere with ventilation or cooling ofmotors, totally enclosed or totally enclosed fan-cooled motors that will not overheat under prevail-ing conditions, shall be used.7 TRANSFORMER SUBSTATION,EXCLUDING BELL AND DRAWING FRAME,TRANSFORMER AND TRANSFORMERS OFSMALL CAPACITY7.1 Every oil-filled apparatus, such as transformer,static condenser, switchgear or oil circuit breakerhaving an individual or aggregate oil capacity of2 000 litres or more shall be housed in a locked,weather and fire resistant building and shall beproperly ventilated to the outside of the buildingonly. The building housing the oil-filled apparatusshall be separated by a distance of not less than 6 mfrom all other buildings.

NOTES1 If the building housing the transformer iswithin 6 m of thesurrounding building there shall not be any door or windowopening in the substation or the surrounding building.2 If the building or compartment housing oil-filled ap-paratus is communicating with another building or com-

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IS 1646 : 1997partment, the substation shall be segregated by separatingwalls of 355 mm thick brick wall or 230 mm thick RCC,carried up to roof level with door openings therein protectedby single fireproof doors of 2 h rating.3 Not withstanding the above, if the substations suppliespower to fire pumps, the same shall be segregated from, theadjoining building by 400 mm thick brickwall or 300 mm thickRCC wall without any door opening therein where, however,dooropenings areabsolutely necessary, he openingsshall beprotected by double fire resisting doors of 2 h rating each. Ifthe substation is attached to a stomyed structure, in additionto segregations, it will also be necessary for the substation tobe provided with RCC slab roof.

7.2 Each oil-filled apparatus, such as transformer,bank of static condensers, including high tensioncircuit breakers, switch and main distributionboards, having an individual or aggregate oilcapacity of 2 000 litres, shall also be segregated fromall other apparatus by 355 mm thick fire resistingbrick wall or 230 mm thick RCC. The separatingwall shall be carried right up to the roof level unlessthe roof is more than 3 m above the highest pointof the equipment, in which case the wall shall becarried up to a height at least 600 mm above the topof the equipment so separated.

NOTES1 This provision need not be applied to furnace and rectifiertransformers as also to transformen of testing apparatus orother equipment ofwhich the transformer is an integral part,whether they are oil-filled or not.2 The requirements given under this rule, however, do notapply to dty type transformers, or transformers having sul-phur hexafluoride, non-flammable coolants and havingprimary voltage not mote than 33 kV.3 If the substation supplies power to fire pumps, separatingwalls as described above will be necessary between thevarious items irrespective of the oil contents.

7.3 Each building or compartment housing oil-filled apparatus containing 2 000 litres or more ofoil shall be provided with oil drains of at least 150mm in diameter and soak pits, the latter being notless than 2.5 m away from the substation. Floorsshall be sloped not less than 1 in 96 towards oildrains. The soak pits shall be of sufficient capacityto take the entire oil content of the equipment anddesigned to provide for drainage of liquids to a safelocation.7.4 A minimum clearance of 750 mm shall beprovided between the transformer or other ap-paratus and enclosing or separating walls.7.5 Substations and switchgear rooms shall only beused to house the intended equipment. Storage ofany kind/or any repair work shall not be permittedtherein.7.6 Suitable apparatus shall be provided in ap-proved positions for the control and protection ofwindings of transformers.

4

7.7 All transformers shall have suitable isolatingequipment on both high and low/medium tensionside.7.8 Cable trenches inside substations shall be filledwith sand, pebbles or similar non-flammablematerials or covered with incombustible slabs. If anumber of cables are taken in a trench, it isdesirable that cables are taken on racks.7.9 All control gears shall be protected againstrodents, reptiles and insects.7.10 It is essential in all transformer houses and inplaces of similar applications that an efficient anddistinctive indicating device be provided to showclearly whether the supply in the main incomingcable is On or Off for the safety of fire-fightingpersonnel in the event of an outbreak of fire.7.11 Transformers and equipment installed out-doors, having an individual or aggregate oil contentof 2 000 litres or more shall be located in a suitablyfenced and locked enclosure separated on all sidesby at least 6 m from any building including substa-tion. Separating walls are necessary between trans-formers having an individual or aggregate oilcontent of 2 000 litres.

8

NOTES1 There should be no door or window opening in the sur-rounding building, if the transformers are within 6 m thereof.2 If the transformers are within 6 m of doors and windowopenings of surrounding buildings then they shall beprotected by single fire proof doors and 6 mm thick wiredglass in steel frames respectively.3 Separating walls shall not be necessary in case of trans-formers having an aggregate oil capacity exceeding 2 000litres but individual oil capacity of less than 5 000 litres if thedistance between transformers and other apparatus is morethan 6 m or if the transformers ate protected by an approvedhigh velocity water spray system.4 Where however oil capacity of individual transformer islarger than 5 000 litres separating walls shall be providedunless all equipment/building/plant are located at a cleardistance of not less than the following:Oi l Capaci ly of ndividual Clear Separat ing

Transformer (1) Distance (m)5 000-20 000 8Over 20 000 15

5 The provisions of 7.1, 7.2,7.3 and 7.11 are not applicableif the transformer is filled with non-combustible insulantliquid.EARTH CONNECTIONS

8.1 All earth connections shall strictlycomplywithIS 3043.8.2 In no case shall gas, steam, sprinkler orhumidifier pipes be used for an earth connection.9 WIRING METHODS9.1 General Requirements9.1.1 Only such wiring methods as are permissiblefor a particular situation or location as laid down inrules under this clause, shali be allowed.

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9.1.2 Wherever aluminium conductors are used,the special precautionary measures laid down inIS 732 shall be followed.9.1.3 Conductors shall be insulated except whereenclosed or bare conductors are specifically per-mitted under the rules.9.1.4 Conductors exposed to oils, greases, vapours,gases, fumes, liquids or other substances havingdeleterious effects upon the conductor or its insula-tion shall be of approved type for the purpose.9.1.5 Conductors may be permitted to be con-nected in parallel (electrically joined at two ends toform a single conductor only) if such conductors areof same length, material and cross-sectional area,have same type of insulation and terminated insame manner.9.1.6 Where cables, conduits, cable ducts or trunk-ings pass through floors, walls, partitions or ceil-ings, the surrounding holes shall be made good withcement or similar incombustible material to the fullthickness of floor, wall, etc. In addition where con-ductors are installed in channels, ducts, trunkingsor shafts passing through floors, walls, partitions orceilings, suitable internal fire resisting barriersshall be provided to prevent spread of fire from oneside to the other.9.1.7 Cables of ac circuits installed in steel con-duits, shall always be so bunched that the cables ofall phases and the neutral (if any) are contained inthe same conduit.9.1.8 Ducts of metal or insulating material andtrunking shall be securely fixed and where they areliable to suffer mechanical damage, shall be ade-quately protected.9.1.9 Trunkings shall be constructed of metal ornon-combustible insulating materials.9.1.10 Cables, cable ductings or trunking of metal-lic construction and conduits may be buried under-ground provided they meet the following minimumearth cover requirement:Wiring Method Minimum Depth of

Earth CoverRigid metal conduits 150 mmOther type of conduits 4.50 mmMetallic ductings or 450 mm (with con-trunkings Crete envelope of notless than 50 mmaround the ducting of

trunking)Directly buried cables 600 mm9.1.11 No wiring system of any kind shall be per-mitted inside ducts needed for transporting dust,loose materials or flammable vapours.

IS 1646 : 19979.1.12 Electrical.services shall not be installed inthe same conduit or trunking as pipes or tubes ornon electrical services like air, gas, oil, water, etc.9.1.13 Only PVC sheathed armoured cables orrigid metallic conduits shall be allowed in ducts orplenums used for movement of environmental air.10 PERMIlTED TYPES OF WIRING METHODS10.1 General10.1.1 Wiring shall be on distribution board sys-tem with main, branch main and final sub-circuitboards fixed at convenient positions and shall con-form to IS 732.10.1.2 Conductors which are not arranged for con-nection to the same system and circuit or whichsupply different phases of the same supply, shall bekept apart throughout their entire run. This shallparticularly apply to installations in which there arepilot lights in addition to the main lighting and thelike.10.1.3 Conductors for final sub-circuits shall notbe enclosed in the same conduit or casing as submain and branch of main conductors.10.1.4 Conductors which pass through windows ordoor frames, wood beams walls, ceilings and floorsshall be protected by porcelain tubes or conduitsaccording to the conditions. The tube or conduitshall extend at least 13 mm on both sides of the walland 25 mm above the floor and below the ceiling.10.1.5 All conduit ends shall be bushed.10.1.6 Cables which are unarmoured shall bemechanically protected up to a height of 1.8 mabove working floor level or up to the height ofswitchboard.10.1.7 Branch main and distribution boards shallbe mounted in suitable accessible positions, nothigher than 2 m above floor level. Adequate work-ing spaces and freedom from danger shall beprovided.10.1.8 Incoming mains shall be used for control ofcircuit in conjunction with suitable circuit breakers.10.1.9 The system of wiring and all other detailsshall be suitable to the conditions prevailing.10.1.10 Linked tumbler switches shall not be usedfor control of circuits.10.1.11 Flexible leads shall hang verticallydownwards from the ceiling rose without anyobstructions, shall not be in contact with shaftingstructural member, pipe work, etc, and shall not becoiled or tied up but cut to correct length.

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ISl646:199710.1.12lexible leads shall be renewed when theyshow signs of deterioration. Joints in flexible con-ductors of pendants shall not be permitted.10.1.13 Flexible leads shall not be used where theyare likely to swing due to ventilation or humidifierapparatus or any other cause; fmed rod or conduitprotection shall be used in such cases.10.1.14 Flexible leads and fittings shall not beallowed to vibrate.10.1.15 Ceiling roses shall be securely fixed andshall be complete with caps.10.1.16 Straight or slanting wall batten holdershall not be fitted at switchboard height or on theswitchboard.10.1.17 Shades or reflectors of light points shallnot be in contact with structural members, pipework, etc.10.1.18 Temporary wiring shall not be permitted.10.1.19 Pendants in close proximity to humidifiersshall be provided with approved water-tight fit-tings.10.1.20 Only rod pendants shall be used in in-dustrial buildings like textile mills, flour mills, sawmills, etc.10.1.21n ducts and tunnels only bulk head fittingswith wires in conduits or armoured cables shall beused for lighting.10.1.22 The base of accessories shall be of vitreousmaterials.

NOTES1 Bakelite ceiling roses may be permitted in industrialbuildings except in areas where the atmosphere is likely tocontain explosive gases or vapours.2 Bakelite switches may be permitted in industrial buildingsexcept in Hazardous Locations as defined later in this code.

10.1.23eflector fittings meant to be suspendedby chain shall not be suspended by string or anyother similar material.10.1.24 Fittings for lamps in places where con-siderable dust or fluff is present (such as willowing,lap breaking, waste opening, mixing, blowing, andraising rooms in textile mills, flour mills, saw millsand other wood working factories, etc) shall be ofdust tight type conforming to IS 4013.10.1.25 In situations where the atmosphere islikely to contain explosive/flammable gases orvapours, fittings of flameproof type shall be usedunless otherwise permitted under clauses relatingto Hazardous Locations.10.1.26 The run or course of wiring shall bearranged to avoid crossing of belt drives; where

such crossing is unavoidable mechanical protectionshall be provided against damage by belt breakages.10.1.27 The paper insulated lead covered cablesshall not be brought right through the sealing boxwithout a break. The conductors of paper insulatedcables shall be terminated in the trifurcating boxand tails of India Rubber (VIR) Conductorssweated by ferrules to the conductors of paperinsulated cables shall be brought through thetrifurcating box.10.1.28 All filament lamps shall be so placed or soguarded as to prevent ignition of combustiblematerial. Any shade or guard used for this purposeshall be suitable to withstand the heat of the lamp.10.1.29 Wiring.of lighting circuits shall be ondistribution board system and circuit diagrams shallbe attached to it.10.1.30 Conductors shall be run as far as possiblealong the walls and ceilings, so as to be accessiblefor inspection.10.1.31 Where two or more points are mounted,with a voltage differences exceeding 230 V betweenthem, a minimum distance of 2 m between thepoints shall be maintained to avoid possibility ofshocks.10.1.32 Cord grips shall be provided for pendantlamp ho!ders of bayonet contact type, and chainsuspended reflector fittings shall have the cableentries made bell-shaped or bushed to avoiddamaging the flexible cables.10.1.33 Chain suspended fittings, fans, etc, shall befixed at a distance not exceeding 250 mm away fromceiling rose.10.1.34 Where long spans occur between beamsand supports, battens shall be provided for attach-ment of conduits, casing, or other wiring or fittings.The runners shall be of well seasoned teak wood,free from shakes, splits, etc, and shall not be lessthan following dimensions:

span (m) Dimensions (mm)1.2 to 1.8 75 x 381.8 to 2.4 75 x so2.4 to 3.4 75 x 633.4 to 4.4 100x75

Alternatively, they may be suspended from acatenary arrangement or be supported on steel sec-tions of suitable size.10.1.35 The wiring for hot air chambers shall bemounted on the walls outside the chamber, as far aspossible. The light fittings inside the chambersshall be of oyster type or shall be waterprooffittings.

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10.1.36 Where wiring is to be carried along the faceof rolled steel joists or stanchions, a wooden ornon-conducting backing, preferably of the fullwidth of joists or stanchions shall first be laid on thejoist or stanchions and secured rigidly thereto.Wooden pieces for the support of casing or conduitto steel joists or stanchions shall be secured bymetal clips with at least two screws.10.1.37 Scaffolding ropes shall not be tied roundconduits, casings or other forms of wiring.10.1.38 All strands of cables shall be fitted intoterminals of switches, fuses, etc; strands of cablesshall not be cut. In damp locations, the strandsshall be soldered together.10.2 The wiring methods specified in 10.3 to 10.7shall only be permitted subject to conditions stipu-lated therewith.10.3 Conduits10.3.1 Conduits and fittings shall be of solid drawnand welded steel of heavy gauge screwed type, con-forming to IS 2667.

NOTE-Rigid non-metallic conduits conforming to IS 9537(Part 3) may, however, be used for low and medium tensioninstallations except in locations mentioned under 9.3.5 andsubject to the following conditions:a) Conduits should be supported not more than 800 mmand should have suitable joints;b) For earthing, separate earthing conductors shall be runinside the conduit from end to end; andc) Expansion joints shall be provided, where required, tocompensate for thermal expansion and contraction.

10.3.2 Solid drawn welded steel conduit shall bepermitted under all atmospheric conditions and inall occupancies subject to stipulations laid downin 10.3.3 and 10.3.4.10.3.3 In damp situations, such as textile sheds, theconduits shail be hot galvanized or zinc impreg-nated or treated with special rust-proof paint.10.3.4 In occupancies like chemical factories,bleach and dye houses, where strong corrosivevapours are present special conduits or conduitswith additional coatings of bitumen paint or with aglass wool lagging provided with a protectivecovering shall be used.10.3.5 Non-metallic conduits shall not beper-mitted in the following locations:

a)b)Cl

Where wiring height is less than 2.5 m aboveworking floor level, unless protected againstmechanical damage;Where exposed to ambient temperatureslikely to be above 55Cat sometime or otherduring the year;In concealed places of combustible con-struction;

d)e)f)

IS 1646 : 1997Where the atmosphere is likely to containflammable gases or vapour;Where conductor operates at voltage above650 V, andIn locations where surrounding atmosphereis likely to affect the non-metallic conduits.

10.3.6 Flexible conduits shall not be used forgeneral wiring. It may be, however used for connec-tions between terminal boxes of motors andstarters, switches and motors but thelength shall berestricted to a maximum of i 200 mm.10.4 Mineral Insulated and Other Types of MetalSheathed Cables10.4.1 Mineral insulated metal sheathed cablesand other types of metal sheathed cables are per-mitted under all atmospheric conditions and in alloccupancies except as mentioned hereunder:

a)b)

Cl Metal sheathed cables of other types shallnot be directly buried under ground, norshall they be used in wet locations unless:1)2)3)

the metallic sheath is impervious tomoisture,a lead sheath or waterproof jacket isprovided under the sheath, andthe insulated conductors under thesheath are approved for use in wetlocations.

Where they would be exposed to destructivecorrosive conditions.Where directly buried under ground,without suitable protection againstmechanical damage and corrosive condi-tions.

10.4.2 In case of wet locations like in parts oflaundries, tanneries, etc, and in locations wherewalls are frequently washed, a minimum clearanceof 6 mm shall be maintained between mineralinsulated cable and the wall to which it is affixed.10.5 Armoured Cables105.1 Armoured cables shall be permitted underall atmospheric conditions and in all occupanciesexcept in commercial garages, storage batteryrooms and in locations where they would be ex-posed to corrosive fumes or gases.10.6 Tough Rubber and Other Non-metallicSheathed Cables10.6.1 Tough rubber or plastic sheathed cablesshall not be permitted in the following locations:

a) Where considerable dust and/or fly ingenerally present (for example cotton andjute mills and other vegetable, fibre process-ing factories, flour mills, saw mills and other7

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IS 1646 : 1997

b)Cld)e>

10.6.2

wood working factories, plastic and rubbergoods factories, pulverising works, etc);Where atmosphere is likely to contain flam-mable/explosive gases or vapours;Where the hazardous trades or processesare carried out (for example, oil mills, paintand varnish factories);Where they would be exposed to mechanicaldamage (godowns, engine rooms, rope andmotor alleys, etc); andWhere wet processes are carried out.These systems shall generally be permittedin office; and residential buildings. Appropriateauthorities may however specially permit their usein industrial buildings of types other than thoseindicated in 10.6.1.

10.7 Cleated Wiring System10.7.1 This system shall be permitted for use inindustrial buildings for low tension circuits only,with prior approval of appropriate authority.10.7.2 When installed in bleaching or dyeing sec-tions of a textile mills, the wiring shall be held byporcelain bobbins secured to teak wood battens bybrass screws and the whole run inverted.10.7.3 This system shall not be used for any type ofbuilding of permanent nature other than of the kindmentioned in 10.7.2.10.8 Cable Trays or Wire or Bus Ducts10.8.1 All cable trays or wire or bus ducts shall beconstructed from earthed sheet metal, enclosed oropen troughs with hinged or removable covershousing and protecting either electric wires andcables, installed at site, or factory mounted bareconductors of aluminium or copper and shall becapable of withstanding electro-mechanical stres-ses.10.8.2 Such systems shall be permitted under allatmospheric conditions and all occupancies exceptin following locations:a>b)C>d)e>

Where exposed to severe mechanicaldamage;Where exposed to corrosive vapours;Where the atmosphere is likely to containflammable or explosive vapours;Where wet processes are carried out; andWhere it is concealed.

10.8.3 The system shall be securely supported atintervals not exceeding 1.5 m.10.8.4 Such systems of totally enclosed type shallbe permitted to be extended vertically throughfloors provided they are adequately protected

against mechanical damage up to a minimum dis-tance of 2.5 m above working floor level.10.8.5 Dead ends of all cable troughs or ducts shallbe closed.10.8.6 Extensions and branches of such systemsshall also be of the same type.10.9 Under Floor Cables Trenches (withinBuildings)10.9.1 Such systems may be permitted under allatmospheric conditions and in all occupanciesexcept where exposed to corrosive vapours andlocations where flammable/explosive vapours orgases may be present, unless the cables or conduc-tors are specially approved for such use or thetrenches are completely filled with sand.10.9.2 Conductors or cables inside the trenchesshall be so mounted on insulated racks or othersupports as to be at least 75 mm above trenchbottoms.10.9.3 The top of the trenches shall be coveredwith removable concrete slabs or chequered plates.10.9.4 In case of long trenches, it is recommendedthat trenches of more than 1000 cm2 cross-section-al area be divided by incombustible barrier walls atintervals not exceeding 45 m. Such barrier wallsshall be of at least 50 mm thickness and of the sameheight as of the cable trench. The cables shall becarried through holes in these barrier walls, whichshall be made good thereafter to prevent passage offire beyond the barriers (see also IS 12459).NOTE - This provision need not be applied if the trenchesare completely filled with sand, pebbles, etc.10.9.5 The combined cross-sectional area of allconductors or cables shall not exceed 40 percent ofthe internal cross-sectional area of the trench.10.9.6 The trench shall be kept free of accumula-tion of water, dust and waste materials.10.10 Compartmentation of Cable Tunnels/GalleriesThe requirements for compartmentation of cabletunnels/galleries should be as per IS 12459.10.11 Flexible Cables and Cords10.11.1 Flexible cabies and cords shall be per-mitted only as:

a) Pendants;b) Wiring of fixtures;c) Connections of portable appliances orlamps;d) Lift cables;e) Wirings for cranes and hoists; and

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IS 1646 : 1997f) Connections to mains-operated electricalstickers and motors mounted on parts of astationary machine, which undergo to andfro motion during operation.

10.11.2 Where a lighting fitting is supported byone or more flexible cords, the maximum mass towhich twin flexible cords may be subjected shall beas follows:Nomi nal Cross- Number and MaximumSecti onal Ar ea of Di amet er Permi ssibl eTw in FlexibleCord, mm2 of L ines, mm Mass, kg

0.5 1610.2 1.70.75 2410.2 2.61.0 3210.2 3.5

10.11.3 Where flexible cables or cords are exposedto risks of contact with oil or petrol or where cablewhich will not support combustion is required, useshall be made of cables or cords having a PVC oroil resisting and fire retardant sheath.10.11.4 Flexible cables and cords shall not be usedas fixed wiring unless contained in earthed metal orany other non-combustible and mechanicallystrong enclosure. This requirement need not, how-ever, apply to short lengths of sheathed flexiblecable or flexible cord used as final connections tofixed apparatus or for connections of control gearof fluorescent lamps or discharge lamps. Non-sheathed flexible cables and flexible cords shall notbe drawn into conduits or ducts.10.11.5 Flexible cables or cords shall also not berun through holes in walls, ceiling or floors orthrough doors, windows or other similar openings.Nor shall they be permitted to be concealed behindwalls, ceilings or floors.10.12 Bare Conductors10.12.1 Bare conductors are permitted for low ten-sion side, of drawing frame transformer circuitswhere the potential difference does not exceed 12volts. Bare or lightly insulated conductors of extralow voltage systems shall have adequate insulationand further protection, where necessary, to ensurethat they do not cause risk of fire.Bare conductors are also permitted for cranes andhoists subject to special conditions laid down in thiscode for such equipment.10.13 Lightning Protection and Overhead Lines10.13.1 The lightning protection system for build-ings shall generally conform to IS 2309.10.13.2 All overhead transmission lines, includingcompound lines shall not be run above any processor storage blocks or open storage site.

10.13.3 Lightning arresters shall be provided forlines at both ends and at supports where exposed toand liable to damage or injury from lightning. Thearresters shall preferably be of the non-horn typefor low and medium tension because of likelydamage by buds and distortion.10.14 Wall Plugs and Sockets10.14.1 All wall plugs and sockets in industrialbuildings shall be of metal clad 3 pin patternseparately controlled by a switch, adjacent to thewall socket.

NOTE - This shall not apply in case of wall plug and socketwith current ratings of 5 amp and less.10.14.2 Where it is necessary to earth the metalcase of wall plug and/or portable appliances, theconnection shall be done with soldered or approvedlugs or crimped joints or any other approved meansof connection.11 LIGHTING, FITTINGS AND ACCESSORIES11.1 Fluorescent Lamp Fittings11.1.1types:

a)b)

c)

These fittings may be one of the following

General purpose t ype - For use in office,residences and similar locations.Industrial ype - For use in places wheredust, fly or corrosivevapours may be present(see Annex B for specification of fittings)..Flame proof explosion t ype - For use inplaces where flammable/explosive gases andvapours are present.

NOTES1 Where fumes or corrosive vapours or gasea evolved dueto chemical action, may be present, the reflector shall be ofvitreous enamel or non-combustible plastic and wiring shallbe in load-sheathed conductors. Rayon Spinning Sectionsshould have lead coated metal reflectors or equipment.2 The position of fittings shall be carefully selected to avoidany mechanical damage by belt drives, shafts, etc, and ifnecessary suitable guards shall be provided. The fittings shallbe clear of the humidifier jets.3 Where flammable/explosive gas orvapours may be presentthe fittings shall be of flame proof type [see IS 5572 (Part 1)for classification of hazardous areas 1.

11.2 Lighting Switchboard11.2.1 Main switches and fuses shall be metal cladand branch main board shall be metal clad whenused on medium tension circuits.11.2.2 All equipment shall be of robust construc-tion, of adequate dimensions and thoroughly dusttight.11.2.3 Each circuit from main distribution centreexcept fuse distribution board shall be provided

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IS 1646 : 1997with a circuit breaker of linked switches andcutouts.11.2.4 Adequate means of control in approvedpositions shall be provided for distribution boardsor a group of distribution boards which are fed froma switchboard or distributing centre and within areasonabledistance therefrom, such as one or moreboards erected in a room or building isolated fromsource of supply.11.2.5 Each final sub-circuit from a distributionboard shall be controlled by a single pole switchconnected to the live, outer or phase conductor.11.2.6 Wood work shall not be used for mountingof or construction of the frame work for iron cladswitch, distribution boards and control gear.11.2.7 All equipment shall be numbered in Englishand vernacular for ready identification and to indi-cate the department, place or circuit controlled.11.2.8 Circuits shall be arranged in symmetry as faras practicable.12 SPECIAL ELECTRICAL EQUIPMENT ANDAPPLIANCES12.1 Radio and Television Sets and SoundApparatus12.1.1 The antenna of radio and television setsshall be connected through a double pole changeover switch so connected that the antenna and theset completely earthed when not in use of during,thunderstorms.12.1.2 The antenna shall be provided with asuitable lightning arresters if situated in an areasubject to heavy thunderstorms.12.1.3 All circuits (aerial and all internal wiring)shall be so constructed that contact with any otherelectric light and power circuits is impossible.12.1.4 The lead-in conductor shall be of copperand shall be not less than 2 mm in diameter.12.1.5 The lead-in conductor shall enter the build-ing through a non-combustible and non-absorptiveinsulating bushing.12.2 X-Ray Apparatus12.2.1 The installation and precautionarymeasures shall comply strictly with Rule 73 ofIndian Electricity Rules.12.2.2 All such apparatus shall be located either inindependent detached building or in compartmentssegregated by 355 mm thick brick walls with each

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supplying power to the fire pumps are not per-mitted within a horizontal distance of:from units and/or storage tanks of plant handlingflammable liquids/gases.

a) 15 m of any process building/plant or tankscontaining flammable liquids, andb) 6 m of any other building of tanks containingnon-flammable liquids or of storage inopen.

12.6.12 The motor rating should be adequate todrive the pump when operating on 150 percent ofrated flow.

In case the feed to such sub-station is by means ofunder-ground cables, the cables shall not passunder any building or permanent structure.12.6.4 Where there is more than one sources ofpower for the operation of pumping set(s), theelectrical circuits shall be so designed as to ensurethat when necessary the set(s) shall continue tooperate without manual operation of any emergen-cy switch, when the supply is interrupted.

12.6.13 The fire pump circuit shall be protected atits origin by an automatic circuit breaker, fromwhich either the no volt coil is removed or which isfitted with automatic re-setting type of no-volt coil,and the overload setting shall be so adjusted as topermit the motor to carry on overload of 50 percentof its rated capacity.

12.6.5 Indicator lamps shall be fitted in prominentposition(s) both in the sub-station and pumphouse, which would continuously glow as long aspower is available to the fire pump(s). A soundalarm shall also be provided in the event of powerfailure to the fire pumps.

12.6.14 Cables for motors of fire pumps and theirswitchgear shall be armourd or shall be enclosed inheavy gauge screwed steel conduit. Overhead linesshall not be permitted within 6 m of window, dooror other opening in any of the protected buildingor any other building within 15 m of a protectedbuilding.12.6.15 Equipment shall be painted throughout inred or in orange yellow colour.

12.6.6 The pump set(s) shall be of direct coupledtype, securely mounted on robust bed-plate(s), if orhorizontal type and should be free from vibrationsat all variations of load.

12.6.16 Pumping sets shall be worked for at least15 min each week and records of the same shall bemaintained.

12.6.7 The motors of fire pumps shall be either oftotally enclosed or drip-proof type, the latterhaving air-inlets and outlets protected with meshedwire panels to exclude rodents, reptiles and insects.12.6.8 The motors shall be wound for Class-Einsulation and the windings shall be vacuum im-pregnated with heat and moisture-resisting varnishpreferably glass-fibre insulated, to withstand tropi-cal conditions.

12.6.17 The incoming cable to the fire pump roomshall terminate in an isolating switch fuse unitincorporating HRC fuses and where necessaryprovided with distribution system.12.6.18 The starting switchgear for the fire pumpsshould be suitable direct on line starting but otheralternative arrangements are acceptable with theapproval of competent authority.13 REQUIREMENTS FOR SPECIALOCCUPANCIES

12.6.9 Motors wound for high-tension suppliesshall have a suitable fixed warming resistance tomaintain the motor windings in a dry condition atall times and particularly under monsoon con-ditions. The resistance shall be fed from mediumvoltage circuits.

13.1 Hazardous LocationsFor the purpose of this code a location shall beregarded as hazardous where any one or more ofthe following conditions exist:

12.6.10 Heating apparatus shall also be provided,when necessary, for medium tension motors wherethey are located below ground level, in order tomaintain the motor winding in a dry conditions.Adequate drainage shall also be provided in thepump house in such cases.

a)

b)C>

Where flammable gases or vapours may bepresent in the atmosphere in sufficientquantities to produce explosive orflammable mixtures;Where combustible dust is produced orhandled; andWhere vegetable or viscose, acrylic andnylon 66 fibres are processed or handled.

12.6.11 The pumping set shall preferably be 13.1.1 In locations where the atmosphere mayhoused in a separate building located at least 6 m contain flammable gases or vapours the clas-away from all other buildings and at least 15 m away sification of areas and selection of Electrical

IS 1646 : 1997

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IS 1646 : 1997Equipment permitted to be installed therein shallbe governed by IS 5572 (Part 1) and IS 5571respectively. These requirements may, however, bemodified in any particular situation as per theprovisions of 13.1.3.13.1.2 In case of process or operations involvingcombustible liquid(s), the presence of flammablevapour in the atmosphere may be deemed probableonly if the flash point of the liquid(s) is below32.2C. However, locations where combus-tible/flammable liquids having flash points above32.2C but not above 93.3C are handled shall beregarded as hazardous if such liquid is (a) sprayedor (b) present in the form of mist or (c) heat to orabove its flash point.13.1.3 Wherever possible, the hazardous locationswhere installation of flameproof electrical equip-ment and fittings is required shall be located eitherin a detached building or in a compartmentsegregated from the remainder of the premises atleast by a non-combustible fire resisting wall of 2 hrating without any kind of opening. Areas where,however, this is not practicable, shall be demar-cated by fencings, railing or boundary lines paintedon floor and all electrical equipment and fittingshall be of flameproof type within the hazardouslocation as also up to a distance from the boun-daries of the demarcated area indicated hereunder:a>

b)

Where the processes or operations neces-sitating the use of flame-proof equipmentand fittings are carried out in the open.All space within 6 m horizontally in anydirection from the demarcating fencing/railing or boundary line and 3 m verticallyabove the highest hazard source.Where the processes or operation neces-sitating the use of flame-proof equipment iscarried out in enclosed space of equipment,as in the case of paint spray booths, bakingor drying ovens, enamelling or coatingequipment, etc.All space within 6 m horizontally of openface or door opening of such equipment and3 m vertically above the roof of such equip-ment.

13.1.4 Except the wiring of rigid metal conduitsand armoured cable wiring, no electrical equipmentor fittings shall be permitted where it may be sub-jccted to hazardous accumulation of readily ig-nitable deposits or residue, as within a spraypainting booth or drying oven.13.1.5 Illumination of spray painting booths orsimilar coating or finishing equipment throughglass panels is permitted, provided the:

a)b)C>,d)

lighting fittings are of fixed type and in-stalled behind glass panels;glass panel(s) is so sealed, that, it effectivelyisolates the lighting equipment from thehazardous area;panels are so located that deposits of haz-ardous residues on them are avoided as faras possible; andglass used for panel is either of the wired orspecially toughened type.

13.1.6 Electrical installation in hazardouslocations involving presence or use of combustibledust or fibre (vegetable, animal or synthetic) shallcomply with the following special provisions:a>

b)C>

4

e>flg>

Wiring methods - The type of wiringmethods permitted shall be as follows:Screwed steel or rigid metal conduits,mineral insulated or other sheathedcables, armoured cables and enclosedmetal COVeTedable or bus ducts.

Motors - Motors shall be either of totallyenclosed, or totally enclosed fan-cooled ordust tight type.Distribution andpanel boards - Location ofdistribution and panel boards wherecombustible dust is evolved shall be avoidedas far as possible.Switchgears - In areas where combustibledust may be present, oil circuit breakersshall be preferred.Lighting fittings - Use of incandescentlamps shall be avoided as far as practicableand the fluorescent light fitting used shall beof industrial type.In case of incandescent lamps being used,the fitting shall be enclosed in dust tightenclosures.The leads from ceiling rose to lamp ter-minals shall be enclosed in conduits.

13.2 Lifts13.2.1 The installation of lifts and care of electricalinstallation shall fully comply with relevantprovisions of IS 1860 and IS 4666.13.3 Petrol Station13.3.1 Electrically Operated valves shall be sodesigned that they can also be manually Operated.13.3.2 The valve or valves shall close automaticallywhen the electric supply ceases.13.3.3 All fusible links in the circuit supplying thevalve or valves shall be in series and on the live lead.13.3.4 The circuit in which the possible links forma path for the current to the fire valve shall be a

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separate final sub-circuit controlled by a switch andby a fuse not exceeding 5A capacity both on the linelead.13.35 Equipment shall be of certified flameproof type unless it is separately mounted and isaway from any possible source of fumes.13.4 Cinematographic Projection and RewindingRooms13.4.1 Where general lighting of the auditoriumand exits can be controlled from within theenclosure, separate and independent means ofcontrol shall also be provided outside the enclosureand well away from it.13.4.2 All switches, fuses and connections thereofshall by totally enclosed and iron-clad and allelectric lamps and resistances so protected as toavoid their possibility of coming into contact withor in close proximity of films or other combustiblematerials. Resistance connected with auditoriumor stage lighting shall not be located in the projec-tion or rewinding rooms.13.4.3 The insulating material of all electric cablesincluding leads to lamps shall be covered with fireresisting material.13.4.4 There shall be no unnecessary and looseelectric cable. The leads to the projector lampsshall be taken as separate circuits from the sourceof supply and from the supply side of main fuses ingeneral lighting circuit. Efficient switches andfuses shall be inserted at the point where the supplyis taken, and, in addition, an efficient double poleswitch shall be fitted in the cinematograph lampcircuit inside the enclosure. When thecinematograph lamp is working the voltage acrossthe terminals of the double pole switch inside theenclosure shall not exceed 110 volts.13.4.5 Cables from projector lamps should betaken as separate circuits from the source of supplyand from the supply side of main fuses in generallighting circuit. Efficient switches and fuses shouldbe inserted at the point where the supply is taken,and in addition, an efficient double pole switchshould be fitted in the cinematrograph lamp circuitinside the enclosure when the cinematograph lampis working the voltage across the terminals of thedouble pole switch inside the enclosure should ex-ceed 110 volts.13.4.6 Resistances shall be made entirely of incom-bustible material and shall be so constructed andmaintained that no coil or other part shall at anytime become undully heated. All resistances, withthe exception of a resistance for regulating pur-poses shall be placed outside the enclosure and, if

IS 1646 : 1997reasonably practicable, outside the auditorium. Ifinside the auditorium, they shall be protected by awire guard or other efficient means of preventingaccidental contact.13.4.7 The operator shall satisfy himself before thecommencement of each performance that allcables, lead connections and resistances are inproper working order. The resistance shall beinspected at least once during each performance. Ifany fault is detected, current shall be immediatelyswitched off and shall remain switchedoff until thefault has been remedied.13.5 Accumulator or Battery Service Stations135.1 Charging shall be carried out in well venti-lated sit,uations and no smoking or naked lightsshall be allowed.13.5.2 Accumulators/batteries shall stand directlyor non-ignitable, non-absorbing, non-conductingmaterial, such as glass, porcelain or glazed earthen-ware. These materials shall rest on a bench whichshall be kept dry and shall be insulated from earth,or constructed of wood. It shall be of slat formationand treated with anti-sulfuric enamel.13.5.3 The accumulators shall be so arranged onthe bench that a potential difference exceeding 12volts shall not exist between adjacent cells. Thebunching of accumulators or arranging them incircular formation shall not be allowed.13.5.4 All combustible material within a distanceof 60 cm measured horizontally, or within 2 metresmeasured vertically, from any accumulator shall beprotected by asbestos sheets.13.5.5 The charging circuit shall be provided withdouble pole switches and fuses, and, where a motorgenerator is employed the motor shall be providedwith double pole switches and fuses and an auto-matic battery cut-out shall be placed in the gener-ator circuit. Any sub-circuit shall be provided witha fuse rated at not more than 7 A in each liveconductor.13.5.6 Charging control panels shall be of durablenon-ignitable, non-absorbent, non-conductingmaterial and together with the rectifiers, trans-formers and supports for resistances of lamps, shallpreferably be fixed to brick or similar wall. If,however, they are fued to wood work, such woodwork shall be covered with hard-asbestic sheets orsimilar fire-resistive material,13.5.7 If accumulators are charged through resis-tance coils or lamps, such resistance coils or lampsshall be at least at distance of 60 cm from thenearest accumulator.

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IS 1646 199713.5.8All wiring shall be securely mounted andprotected against mechanical injury and efficientterminal or connections shall be provided fromwhich the connections to the accumulators can bemade. Rubber or P.V.C. insulated wiring, if oninsulators shall not be run in such a position that afire arising at any accumulator could reach it. Allconductors connecting supply terminals to theaccumulators shall have either rubber or toughcompound insulation without a tape or braid.13.5.9 If the supply is taken from mains having oneconductor earthed, the lamps or other resistancesshall be connected on non-earthed lead and theaccumulators connected direct to earthed conduc-tor. Precaution shall be adopted to prevent theattendant receiving shocks.13.510 Celluloid-cased accumulator shall not bekept on charge at any time without an attendant.13.511 Spring-jacks shall be used for final connec-tion to the accumulator terminals.13.5.12 All insulators shall be kept as dust free aspracticable.13.6 High-Rise Buildings13.6.1 All electric distribution cables/wiring shallbe laid in a separate fire resistant duct. The ductshall be sealed at every floor with non-combustiblematerials having the same fire resistance as that ofthe duct. Low and medium voltage wiring runningin shafts and in false ceiling shall run in separateconduits.13.6.2 Separate circuits for water pumps, lifts andstaircase and corridor lighting and blowers inpressurising system shall be provided directly fromthe main switchgear panel and these circuits shallbe laid in separate conduits so that fire in onecircuit will not affect the others. Master switchescontrolling essential service circuits shall be clearlylabelled.13.6.3 Staircase and corridor lights shall be onseparate circuits and shall be independently con-nected so that it could be operated by on switchinstallation on the ground floor easily accessible tofire fighting staff at any time.13.6.4 A standby electric generator shall be in-stalled to supply power to staircase and corridorlighting circuits, fire lifts, the electrically operatedfire pumps, pressurising fans and blowers in case offailure of normal electric supply.13.65 If more than 200 litres of oil are containedin any oil immersed electric gear a retaining sillthreshold shall be provided around,the gear or atthe door.

14 GODOWNS14.1 GeneralWiring shall either be in rigid steel conduits orarmoured cable. Wall brackets shall be eliminatedand rod pendants and batten holder fittings shall beerected for the lamps which shall be of a typeprotected against mechanical damage. Industrialtype fluorescent light fittings shall, however, bepermitted. The fittings for lamps shall be fmed atsufficient height above the highest level of bulk orother goods which are stored in the godown. Thecircuit shall be controlled by a linked switch andcut-outs which shall be placed outside the godownin a convenient portion.14.2 Raw Jute.Godowns14.2.1 The supply of electricity shall be at lowvoltage, that is, not exceeding 2.50 volts.14.2.2 All wiring shall be encased in screwed steelconduits, the horizontal portions of which shall besloped to allow condensed moisture to collect at setplaces where drainage outlets shall be provided.Such outlets shall be properly secured, againstentry of insects, etc.14.2.3 The cable used shall not be of less than3/.029 size of 250-V grade and shall be of singlecore, rubber or PVC insulated, taped and branded.14.2.4 No joint boxes,or cut-outs of cables shall beallowed inside the godown.14.2.5 The conduit shall be affixed to (not recessedinto) walls or roofs of godowns by means of saddlesgrouped on walls or roofs, the distance betweensaddles not exceeding 750 mm. All conduits mustbe laid externally on the outside walls or roofs ofthe godown except those lengths which are requiredto carry the cables to light fittings. In the latter case,the conduit should be run above the level of higheststacking.14.2.6 Only bulkhead light fittings of approveddesign with C.I. frames of robust construction andbulkhead glasses protected with thick steel linedguards shall be used.14.2.7 Each lighting fittings shall be affixed to thewall or at not more than 450 mm below the roof ofthe godown. In case of a sprinklered godown eachlighting fitting shall either be above the level of thesprinkler heads or not less than 300 mm below thatlevel, it being understood that in no case shall alight fitting be installed low than 750 mm above themaximum stacking height.14.2.8 All lights in the godown shall be controlledby one or more double pole metal-clad switches and

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IS 1646 : 1997fuses situated outside the godown in a convenientplace and effectively protected from weather.14.2.9 An indicator light controlled by theswitch(es) shall be provided on the switch panel toshow whether the lights inside the godown are onor off when the godown is closed and locked.14.3 Strong Rooms14.3.1 Permanent lighting shall be provided bymeans of concealed wiring or solid drawn conduitwiring with the main switch located outside.14.4 Nitrocellulose (and Chemicals HavingSimilar Fire Hazard Characteristics) Godowns14.4-l Lamps in nitrocellulose storage rooms shallbe rigid fixtures of glass enclosed and gasketted typeor flameproof fluorescent fittings. Lamps shall becontrolled by a switch having a pole in each un-earthed conductor. This switch shall be locatedoutside the room and provided with a pilot light toindicate whether the switch is on or off. Thisswitch shall disconnect from all sources of supplyall unearthed conductors terminating in any outletin the room.14.4.2 No socket outlets, electric motors, heaters,portable lights or other portable electric equip-ment shall not be located in nitrocellulose storagerooms.15 TESTING15.1 The electrical installation in a new building oran addition to an existing installation shall be testedas per IS 732 before it is put to service. The instal-lation shall also be checked periodically as decidedby the appropriate authority.

15.2 The following tests shall be carried out asrequired by the appropriate authority:a)b)

Cl

d)e)

Full load and/or flash tests of rotatingmachinery, transformers, condensers,rectifiers, etc.Insulation resistance tests of rotatingmachines, transformers, condensers,regulators, cable circuits, etc, by meggers ofappropriate voltage.Lighting circuits shall be tested in followingmanner:1)

2)

3)

All switches on and consumingdevices in circuit, both poles con-nected together to obtain resistance toearth,Between poles with lamps and otherconsuming devices removed andswitches on; andWith lamps and other consumingdevices in position but switches off.

Earth continuity tests.Power circuits to be tested between phasesor outer and middle or neutral wires and toearth.

15.3 The appropriate authority shall have the rightto vary the foregoing tests or carry out further testsas may be considered necessary.16 INSPECTION16.1 All electrical inspections shall be inspected.periodically and proper vigilance shall be kept.Any faults or defects that are notice shall be at-tended to and the defects rectified immediately.

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IS 1646 : 1997

ANNEX A(Clause 2)

LIST OF REFERRED INDIAN STANDARDS

IS No. T i t l e IS No. T i t l e732 : 1989

1860 : 1980

2309 : 1989

2667 : 1988

Code of practice for electricalwiring installations ( thirdrevision)Code of practice for installation,operation and maintenance ofelectric passenger and goods lifts(first evi sion)Code of practice for the protec-tion of buildings and allied struc-tures against lightning (secondrevision)Fittings for rigid steel conduits forelectrical wiring (first evi sion)

4666 : 1980 Electric passenger and goods lifts(first evi sion)

5.571 : 1979 Guide for selection of electricalequipment for hazardous areasCfirst evi sion)

5572 : 1994 Classification of hazardous areas(other than mines) having flam-mable gases and vapours forelectrical installations (secondrevision)

9537 Conduits for electrical installa-(Part 3) : 1983 tions: Part 3 Rigid plain conduitsof insulating materials3043 : 19874013 : 1967

Code of practice for earthing 12459 : 1988 Code of practice for fire-protec-Dust-tight electric lighting fit- tion of cable runstings

16

http://../link/61to88/732.Bishttp://../link/61to88/732.Bishttp://../link/61to88/732.Bishttp://../link/15to30/1860.Bishttp://../link/15to30/1860.Bishttp://../link/15to30/1860.Bishttp://../link/15to30/2309.Bishttp://../link/15to30/2309.Bishttp://../link/15to30/2309.Bishttp://../link/15to30/2667.Bishttp://../link/15to30/2667.Bishttp://../link/15to30/2667.Bishttp://../link/31to60/4666.Bishttp://../link/31to60/4666.Bishttp://../link/31to60/4666.Bishttp://../link/31to60/5571.Bishttp://../link/31to60/5571.Bishttp://../link/31to60/5571.Bishttp://../link/89to99/9537_3.Bishttp://../link/89to99/9537_3.Bishttp://../link/89to99/9537_3.Bishttp://../link/15to30/3043.Bishttp://../link/15to30/3043.Bishttp://../link/15to30/3043.Bishttp://../link/31to60/4013.Bishttp://../link/31to60/4013.Bishttp://../link/31to60/4013.Bishttp://../link/12/12459.Bishttp://../link/12/12459.Bishttp://../link/12/12459.Bishttp://../link/12/12459.Bishttp://../link/89to99/9537_3.Bishttp://../link/31to60/5571.Bishttp://../link/31to60/4666.Bishttp://../link/31to60/4013.Bishttp://../link/15to30/3043.Bishttp://../link/15to30/2667.Bishttp://../link/15to30/2309.Bishttp://../link/15to30/1860.Bishttp://../link/61to88/732.Bis

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IS 1646:1997ANNEX B

(Clause 11.1.1)FLUORESCENT LAMP FIITINGS

B-l GENERAL PURPOSE TYPE FITTINGSB-l.1 The general design of reflectors shall be ofsuitable type and material. The material shall beany suitable metal or plastic. If plastic of a combus-tible nature is used, it shall not be in contact withany electrical conducting part and shall not igniteby the radiation from the lamp.B-l.2 The auxiliary equipment, that is, choke coil,power-factor condenser and stating unit (compris-ing thermal switch, radio-suppresser condenser)shall comply with relevant Indian StandardsSpecifications and shall preferably be mounted onthe lamp fitting itself in a dust-tight enclosure, butif any item is mounted separately it shall bemounted on parts made of non-combustiblematerial.B-l.3 The wiring connections between the equip-ment, that is, chockes and condensers, shall be inPVC insulated wiring, properly clamped as neces-sary.B-l.4 The suspension shall be made by two con-duits or rods or robust chains, spaced to shareequally the weight of the fitting.B-l.5 The lamp or tube holders may be of plasticmaterial provided these are of efficient and ap-proved design, and that each tube is securely heldby suitable metal spring clips at each end.B-l.6 Earthing of the fixture shall be made with anunbroken conductor, the suspension chains (whereemployed) shall not be regarded as an approvedmeans of earthing.B-l.7 Fluorescent fixtures may be suspended fromconduit wiring junction boxes as a means to preventexposure of conductors from the fitting to thewiring in the conduit. The connection inside thejunction box shall be made to a porcelain junctionbase. Plain procelain connectors shall not be per-mitted in the box.B-2 INDUSTRIAL TYPE FITTINGSB-2.1 Mild steel trough suitably enamelled orpainted or any other robust reflectors shall be usedwhich may, if necessary, have upward lighting slots.

B-2.2 The auxiliary equipment, that is, choke coil,power-factor condenser and starting unit (compris-ing thermal switch and radio-suppresser con-denser) shall conform to relevant Indian Standardsand shall be mounted on suitable framework in aseparate detachable dust-proof non-ventilated box,with tight fitting covers securely fixed by machinescrews and bolts to the main trough.B-2.3 The wiring connections between the equip-ment housed in the choke and condenser box shallbe vulcanised rubber insulated flexible cabling orapproved PVC insulated conductors in heavygauge, welded or solid-drawn steel conduit, or runinternally and properly clamped.B-2.4 Suspension shall be made by two conduitsspaced to share equally the weight of the fitting.Each conduit rod shall be provided with a springloaded ball-and-socket joint ceiling plate at the top,and the other end shall be bolted to the trough.B-2.5 lamp or tube holders shall be made of plas-tic, provided an efficient and approved design isemployed and each tube is held with suitable metalspring clips at each end.B-2.6 Earthing of fixtures shall be made with anunbroken conductor.B-2.7 Fluorescent fixtures may be suspended fromconduit wiring junction boxes, as a means toprevent exposure of conductors from the fitting tothe wiring in the conduit. The connection insidethe junction box shall be made to a porcelain junc-tion base. Plain procelain connectors shall not bepermitted in the box.B-2.8 The chokes of all fluorescent fittings shall bemounted on incombustible material.B-2.9 Incoming twin twisted flexible conductorshall enter the side of the box through a dust-tightbushed hole.B-2.10 The lighting tubes and reflectors shallbe kept clean to obtain maximum efficient light.Cleaning shall be carried out by competent per-sonnel.

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IS1646:1997

ANNEX C(Foreword)

FIRE SAFETY SECTIONAL COMMITTEE, CED 36Chairman Represenri ngShri J. N. VAKILMembers

Tariff Advisory Committee, MumbaiSHRI . RAVE Alternate toShri .I. N. Vakil)DR A. K. BHALLADR K. S. UPPAL Alternate)SHRIM. M. KAPOORSHRIRANA PRATAP Alternore)S~.P.I . N. CHAKRABORTY&RI P. K. MAJLIMDARAltonate)CHIEFFIRE OFFICERSHRIS.M. E~AI

Ministry of Defence (CEESO), New DelhiEngineers India Ltd, New DelhiTariff Advisory Committee, Chennai /Calcutta

SHRIRAMEZSH HOBLEYSHRI S. K. DHERI

SHRIR. C. SHARMA Alternate)SHRIK. P. SHARMA

Assrr SECURITVCOMMISSIONERAlternate)FIRE ADvlsoRy

DY FIRE ADVISOR Alternate)SHRIJ. S. GAHLAUTSHRIP. N. GHOSHSHRIC. P. GOSAINSHRIS. C. GLJ~~A

SHRISANJEEV NGRA (Ak?~~tc)SHRi S. K. SHANGARI

LT-COL A. T. PARNAIKSHRIG. B. MENONMEMBER (HYDRO - CON~IWCXON MON~RING)

CHIEFENGINEER HTD-II) (Alternate)SHRIV. B. NIKAM

Municipal Corporation of MumbaiMumbai Fire Brigade), MumbaiIn personal capacity (B-46 A. G. Khan RoadM unicipal o@xrs Sociery, Worl i, M umbui)Bhabha Atomic Research Centre, MumbaiDelhi Fire Service, Government of Delhi, New Delhi

Ministry of Railways, New DelhiMinistry of Home Affairs, New DelhiState Bank of India, MumbaiIn personal capacity (J-1916, Chirrarunjun Park, New Delhi 19)Central Public Works Department, New DelhiLloyd Insulations (India) Pvt Ltd, New DelhiEngineer-in-Chiefs Branch, New DelhiIn personal capacity (A-5, Puzhukkaru Pa& m, Vennala, Cochin)Central Electricity Authority, New DelhiIn personal capacity (4134,Haji A l i Municipal Off icers Cooperat ive

SHRID. PADANABHASHRIB. S. VENKATE~HAlternate)

SHKIP. N. PANCHALRETD DY INSPECTOR ENERAL FIRE) CISF

PKESIDENTSHRIV. M. RANALI~ARSHRIR. N. CHAChlUSHRIA. R. KHAN

SHRINATARAJAN Ahernure)DRT. . HARMA

DR GOPAL KRISHNAN AIremure)SHRI . SUNDARAJAN

SHRIS. K. CHA~OPADHAYAY (Airemure)SHRIM. .~AGI

SHRI . K. SAKSENAAlremare)MANAGINGDIRECTOR

SHRIT. V. MADHUMANIAlternate)SHRI . K. SHARMA,

Director (Civ Engg)

Housi ng Society, M umbui)Tata Consulting Engineers, MumbaiIn personal capacity (46, Bl ock E-l, Pocket- 11, Sector I S, Rohini , Delh i)Institution of Fire Engineers (India), New DelhiMinistry of Petroleum and Natural GasMetallurgical and Engineering Consultants (India) Ltd, RanchiBharat Heavy Electricals Ltd, BhopalCentral Building Research Institute, RoorkeeNational Thermal Power Gxporation Ltd, New DelhiMinistry of L&our (Regional Labour Institute, Kanpur), New DelhiLoss Prevention Association of India Ltd, MumbtiDirector General, BIS(Ex -0flci o Member)M ember Secreta ryS. CHATLJRVEDI

DY DIRFXXOR CIVIL ENGG), IS

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Bureau of Indian StandardsBIS is a statutory institution established under the Bureau of I ndian Stat1dard.s Act, 1986 to promoteharmonious development of the activities of standardization, marking and quality certification of goods andattending to connected matters in the country.Copyright

BIS has the copyright of all its publications. No part of these publications may be reproduced in any formwithout the prior permission in writing of BIS. This does not preclude the free use, in the course ofimplementing the standard, of necessary details, such as symbols and sizes, type or grade designations.Enquiries relating to copyright be addressed to the Director (Publication), BIS.Review of Indian StandardsAmendments are issued to standards as the need arises on the basis of comments. Standards are also reviewedperiodically; a standard along with amendments is reaffirmed when such review indicates that no changes areneeded; if the review indicates that changes are needed, it is taken up for revision. Users of Indian Standardsshould ascertain that they are in possession of the latest amendments or edition by referring to the latest issueof BIS Handbook and Standards Monthly Additions.This Indian Standard has been developed from Dot: No. cED 36 (5418).

Amend No.Amendments Issued Since Puhlicntion

Date of Issue Text Affected

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Manak Bhavan, 9 Bahadur Shah Zafar Marg, New Delhi 110002Telephones: 323 0131,323 33 75,323 94 02Regional Offices:

Telegrams: Manaksanstha(Common to all offices)

Telephone*Central : Manak Bhavan, 9 Bahadur Shah Zafar MargNEW DELHI 110002Eastern : l/14 C.I.T. Scheme VII M, V.I.P. Road, Maniktola

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132 92 95,832 78 58832 78 91,832 78 92