COPPER EARTHING: Earthing of Sheet metal/ iron clad switches and metallic cases etc., with 20 mm x 3 mm thick electrolytic copper tape rivetted (with 10 nos. copper rivets) to 30 cm x 120 cm x 3 mm thick tinned copper plate (made cylindrical) burried 10 metre below ground level in the hole of excavation having bore dia. 125mm and surrounded by salt & charcoal dust mixture (20 kg.) including fixing the copper tape on wall and in floor etc., up to 13 metre in length (including bore length). G.I. pipe 20mm dia. (A-class) should be laid in the hole of excavation from bore surface level to 1 feet below ground level and having wire mesh funnel fixed on the top level of the pipe. 300mm x 300mm x 300mm deep haudi of bricks finished with 1:4 cement plaster and haudi covered with cast iron lid having size 300mm x 300mm around the hole of excavation.