Revamping of Earthing System

Laying, routing and fixing of 65 x 10 mm GI earth flats (supplied as 6 mtr pieces) to form the earth ring network of TP unit to interconnect all the in plant substations, panel rooms, heavy equipments, structurals etc with the Main step down station of KMML. The GI strips shall be laid through existing cable trays, structurals, walls, ground etc by interconnecting to form a ring structure. The joints shall be properly cleaned full length lap welded and shall be painted with two coats of zinc chromate paint over two coats of zinc chromate primer with bitumen tape over it. (a minimum of one weld joint for every 6 meter length of strip and carrying out additional weld joints wherever required based on cut lengths and site conditions). The welding shall be continuous, mechanically strong and electrically sound to ensure proper continuity of earthing system. Electrical continuity to be checked and recorded at each weld joints (R<0.01 ohms). A minimum of one disconnecting type test lead of 65x10 x 200 mm with 2 sets of GI bolts, nuts and washers complete at each end shall be provided for each earth mat (approximately 40 numbers) duly connected to the earthing system with suitable terminations, insulators, mounting arrangements and hardware, ensuring ease of access for periodic testing and measurement of earth resistance with applicable standards and specifications.The test link shall be installed in an accessible location from ground to facilitate isolation of earth electrode. The cable trays shall be connected to earth strips using GI bolts and nuts at every 6 meter intervals. The GI flat shall be connected to GI cable trays with 1C x 16/25 sqmm earth cables using cable lugs, GI bolts, nuts washers complete. The required cable for earthing shall be supplied by KMML. Final resistance of the ring network shall be less than or equal to 0.5 ohms. All works shall be carried out in strict compliance with IS 3043 and IEEE 80 guidelines. 65X10 mm GI flats will be supplied by KMML. All other materials/consumables like GI bolts, nuts, washers, bitumin, jute, insulators for mounting test links etc included in the scope of the contractor.