SPECIAL REPAIR TO EARTHING PITS AND LIGHTENING ARRESTERS AT AF STATION CHIMNEY HILLS

Material & Labour for earthing complete with GI earth plate electrode 60 cm x 60 cm x 6 cm thick buried directly in ground vertically at a depth not less than 2.25 m below normal ground level with top level of earth plate at depth not less than 1.5 m below normal ground level surrounded form all sides by 15 cm thick and packed layer of charcoal dust and common salt filling in alternate layers and electrode connection by using 25x4mm GI strip by means of bolts, nuts, check nuts and washers of galvanized iron upto test point and protected by GI pipe light grade 40 mm bore up to 7.5 Mtr connected to a main switch board or main control board and GI pipe light grade 20 mm bore for watering and including funnel, wire mesh, 80 mm thick pre-cast RCC 1:2:4, type B-1 cover reinforced with hard drawn steel wire fabric weighing not less than 4 Kg/Sqm in lieu of CI cover, PCC 1:3:6 type C2 pit / chamber including all necessary excavation and earth work, disposal of surplus soil to a distance not exceeding 50 m all as specified and as shown in Electrical Plate No3 of MES Schedule Part – I of 2009.

Material & Labour for Chemical Earthing with copper Earth plate 900x600x5 mm buried directly in ground (earth pit not less than 3.50 mtr deep below ground level) with top edge of the plate not less than 2.6 mtr below normal ground level, connected to copper earth lead strip of size 32 x 6 mm by means of bolts, nuts , check nuts and washers of tinned copper / brass in addition to brazing of all joints including excavation and eatth work, GI pipe light grade 40 mm bore for protection to earth lead including charcoal dust 200 Kg, common salt 200 Kg and Megnisium Sulphate 150 Kg , PCC 1:2:4 type B1 used 20 mm graded stone aggregate in chamber and mild steel angle Iron frame 40 mm x 40 mm x 3 mm and 40 mm thick RCC 1:2:4 type B1 using 20 mm graded stone aggregate as in cover slab reinforced with 8 mm dia TMT bar both ways at 100 mm C/C GI funnel and wire mesh 25 mm bore GI pipe light grade for waterning including necessary earth work and testing complete. NOTE: (I) Earth plate shall be laid in vertical plane such a way that shorted side remains vertical. (ii) Earth plate shall have minium cover of 300 mm thick of charcoal / salt on all sides including top and bottom. (iii) Charcoal and salt shall be laid in alternate layer of 150 mm each with total eight layers (each 4 layer of charcoal and salt). (iv) the earth test point of Gun metal / phosphorus bronze shall be located all as specified and directed by Engr-in-Charge.

Supply & Fixing for Copper strip 20 x 3mm with saddles and fixing screws for fitting screws etc. for pole and down conductors above ground including hook .

Repairs to old broken / damaged steel earth pit cover by replacing MS sheet cover 5 mm thick with iron angle frame including fabrication with lifting facility and fixing on existing earth pit as per site requirement all as specified and directed.

Supply & Fixing for Insulator for copper/Gi strip all as specified and directed

Supply & Fixing for single pointed air termination copper rod 12mm dia and 300mm long and fixing on roof/poles with base insulation materials nut bolts clamps, nuts, bolts and washers etc complete all as specified and directed

Supply & Fixing in repair PVC insulated Copper cable single core multistranded of size 25 Sq mm dia including flxible PVC conduit pipe complete all as specified and directed.

Material & Labour for Painting work for Conventional earth pits (i.e. Lightening arrestor,Signal earth,Equipment earth,Power supply earth ) by two coats yellow paints all as specified and directed

Material & Labour for Painting work for Chemical earth pits (i.e. Lightening arrestor,Signal earth,Equipment earth,Power supply earth ) by two coats red paints all as specified and directed

Repairs/replacing old broken / damaged earth pit Chamber and pit cover by new chamber cover made out of PCC 1:2:4 Type B1 using 20mm graded stone aggregate for repair to existing earthing chamber /chamber cover and making New as per site required all as specified and directed .