CONVERSION OF NINE CONVENTIONAL EARTH PITS TO CHEMICAL EARTH PITS AND PROVN OF FOUR ADDL CHEMICAL EARTH PITS FOR CSDO BUILDING UNDER GE (AF) SUBROTO PARK, DELHI CANTT-10

Disconnecting and taking down unserviceable earthing any type & size including all accessories from installations/ bldgs/ communication centers complete all as directed by Engr-in-Charge.

Material and Labour for Conductive Concrete Earth Grid of multiple interconnected Earth Electrodes to achieve the earth resistance value of less than < 3 Ω. The excavation is to be carried out in any type of soil including hard rock. The necessary soil treatment to be carried out to achieve the desire result. The approx specification are as under:- (i) Earth Electrodes: Metal conductor - Copper bonded MS rod dia 17.2 mm (+/-.5mm), Length 3 meter with conductive concrete with bore dia 85mm to 100 mm, Length 3 meter of earth electrode. (ii) All earth electrodes should be installed in specially treated soil earth pits of size 1.5 meter x 1.5 meter x 3 meters each (Minimum four Earth Pits) shall be prepared by removing high resistivity soil/ rock. The earth pits to be filled with fresh low resistivity sieved soil and compacted with water. The soil treatment chemical should be non corrosive, highly conductive & there shall not be need of water for electrical conductivity. (iii) Interconnected Strip: All the multiple Earth Electrodes will be horizontally interconnected with metal conductor - Copper strip flat size : 25mm x 3 mm & conductive concrete embedding size : 75 mm². (iv) Test Link : Test links - Copper strip flat size : 50 mm x 6 mm x 200 mm shall be provided, at any one of the four Earth Electrodes of the grid for connection between earth grid pit and application. (v) Pit Cover : RCC pit cover & frame shall be provided at all Earth Electrode (with test links). (vi) Two Nos of earth strip of size 25x3mm shall be laid from earthing to test point and duly embedded in conductive concrete of size 75 mm2. (vii) Each earth pit base to be provided with strip mesh of size 1200mmx1200mm usinbg copper earth strip of size 25x3mm. Mesh shall be made with 7 Nos of GI strip in length and width and embedded in condutive concrete of 100mm thick.

Supply and fixing of Earth continuity conductor or main earthing lead fixed to wall on batten or recess or chases or burried in ground or drawn in conduit/pipe or fixed to poles or any other indicated situation for loop earthing etc. as required of size 20x3mm copper strip complete all as specified and directed.