Specifications

159
NLUO PMC CONTRACTOR
SIGNATURE AND SEAL SIGNATURE AND SEAL SIGNATURE AND SEAL
2. MATERIALS :
All materials, fittings, appliances, used in electrical installations, shall conform to Indian Standard Specifications wherever
these exist. A list of approved materials is attached afterwards. Materials not included in the list shall be got approved by the
Architects / Engineer-in-charge / Owner prior to actual use.
3. MAIN SWITCH GEAR :
Iron clad switch fuse and isolator units should conform to B.S. 861 (I.S. 2510-1954). The quick made and break mechanism
shall be self interlocked with the cover. In “Off” position there must be two breaks per pole.
Main switch gear shall be properly earthed with two numbers conductors if M.V. and one number of L.V.
4. BUSBAR CHAMBER (BBC) :
This shall be totally enclosed, metal clad type fabricated from rust proofed 14 SWG sheet steel on angle iron frame and
provided with sheet or cast iron cover and undrilled detachable and plates, suitable for mounting angle iron floor stand and
painted with high quality enamel paint. G.I. bolts and nuts shall be used for assembly with suitable packing materials to ensure
dust proof finish. Meters shall be provided on suitable sheet steel boxes. Switch shall be provided with cable and boxes as
required.
The depth of B.B.C. shall be 150 mm (minimum). Minimum clearance of phase bars to earth shall be 25 mm and between bus
bars shall be minimum 32 mm.
H.C. (High Conductivity) copper bus bars properly tinned are to be rated at 1000 amps. per sq. in and aluminum bus bars
(wrought aluminum alloy strip) conforming to relevant I.S. specification at 800 amps per sq. in.
Neutral Bus bars are to be rated to carry 60% of phase current. These shall be carried on glazed porcelain supports of proper
dielectric and mechanical strength and shall be appropriately colour coded for identification of phase.
Lettering shall be done for identification of switches as directed. The contractor shall submit fully dimensioned Tendered
Drawing of the board with the physical position of the switches and other components to the Architects for their approval
before the same is fabricated.
There shall be two numbers of Earth Terminals Suitable Danger Board shall be provided.