provision of 66 nos of additional maintenance free earth pit at 110kv kilpauk water works ss ( 15 nos ) , 33 / 11kv periyar nagar ss ( 12 nos ) , 33 / 11 kv paper mills road ss ( 8 nos ) , 110 / 33 kv manali ss ( 16 nos ) and110 / 33 kv mathur ss ( 15 nos ) .; 1 maintenance free earthing in various ss of chennai north circle as detailed in schedule-a of the specification 2 supply of maintenance free earthing system set consisting of one copper bonded earthing electrode 14.25mm dia, 10 feet length with 250 micron copper bonding along with two bags ( 11.3 kg each ) of ground enhancement matrial ( gem-25a ) and one h-clamp 3 additional earth h-clamp 4 erection charges for hard rocky soil - vertical : making the bore of 9inch dia upto 15 feed deep by using mechanical drilling machine and fill up the bore using black cotton soil / agriculture soil, installation of earthing system 5 labour charges - digging of trench for laying of ms flat, erection of 50 x 6 mm ms strip, cutting and welding on all sides for interconnection of earth pits and earth mat 6 supply of m.s. flat 50 x 8mm for interlinking of earth pits 7 supply of earth pit cement collar 6 inch height & 1 feet diameter