GENP-67/2021-22 PROVN OF EARTHING PIT FOR CRITICAL EQUIPMENTS AT AF STN PALAM UNDER GE AF PALAM

Amount

Supply, installation, testing and commissioning of maintenance free earth electrode of size 100 mm Dia x 30.5 Mtr long with 17.2 mm Cu bonded MS conductor pre cast or in-situ cast in high purity electrically conductive granular material having ultra low resistive value of 0.001 Ohm-m. Electrode made of conductive earth enhancing material mixed with cement in the ratio of 3:1 to achieve result of earth resistance less than 1 Ohm encase or backfill the voids surrounding the 17.2 mm Cu Bonded MS conductor or other metal components placed in augured bore hole of 100mm dia x 30.5 Mtr depth, resulting to increase in the effective surface area of the earth electrode or grids to lower the resistance. Earth enhancing matetial should not leach chemicals into the adjacent soil or underground water channels and should be in pH neutral range. Earth enhancing material should permanently protect the encased metal components of the earthing system, copper bonding on MS rod should be minimum 250 microns. All hardware like nuts, bolts and washers should be of stainless steel. Electrode should withstand fault current upto 35 KA for 1 second. Electrode's top terminal be sealed permanently packed with conductive concrete and Cu bonded MS/ copper strip taken out be terminated on to earth test point and equipment terminal. Test certificate of NABL laboratory shall be submitted by the contractor, test link of size 50 mmX6mm X200mm, RCC pit cover including brazing of all the joints upto test point complete, all as specified and directed by Engineer-in-Charge. Make of electrically conductive earthing material: Macronite or Its equivalent as approved by Command Chief Engineer/E-in-C Branch with same earthing category

Supply, installation, testing and commissioning of maintenance free earth electrode of size 100 mm Dia x 15 Mtr long with 17.2 mm Cu bonded MS conductor pre cast or in-situ cast in high purity electrically conductive granular material having ultra low resistive value of 0.001 Ohm-m. Electrode made of conductive earth enhancing material mixed with cement in the ratio of 3:1 to achieve result of earth resistance less than 2 Ohms encase or backfill the voids surrounding the 17.2 mm Cu Bonded MS conductor or other metal components placed in augured bore hole of 100mm dia x15 Mtr depth, resulting to increase in the effective surface area of the earth electrode or grids to lower the resistance. Earth enhancing matetial should not leach chemicals into the adjacent soil or underground water channels and should be in pH neutral range. Earth enhancing material should permanently protect the encased metal components of the earthing system, copper bonding on MS rod should be minimum 250 microns. All hardware like nuts, bolts and washers should be of stainless steel. Electrode should withstand fault current upto 35 KA for 1 second. Electrode's top terminal be sealed permanently packed with conductive concrete and Cu bonded MS/ copper strip taken out be terminated on to earth test point and equipment terminal. Test certificate of NABAL laboratory shall be submitted by the contractor, test link of size 50 mmX6mm X200mm, RCC pit cover including brazing of all the joints upto test point complete, all as specified and directed by Engineer-in-Charge. Make of electrically conductive earthing material: Macronite or Its equivalent as approved by Command Chief Engineer/E-in-C Branch with same earthing category Note :- (i) Test certificate of earthing material from certified NABL laboratory shall be submitted & verified by GE. Test certificates shall be kept in record by GE. (ii) Payment of Earthing shall be allowed only if result of earth resistance is achieved below specified value. (iii) Manufactures warranty for performance of resistance value less than specified values for period of min 25 years after commissioning shall be provided by contractor.

M&L for Earth continuity conductor or main earthing lead fixed to wall or recess or buried in ground or drawn in conduit/pipe or fixed to poles or any other indicated situation for loop earthling etc. as required with 20mmx3mm copper strip complete with and including brazing of copper strips and earthing insulators fixed to walls all as specified and directed by Engr-in-Charge.

LAIQ RAM VERMA

RUHI ASSOCIATES

BRIJ MOHAN LAL AND CO.

MAHABIR SINGH

SM CONSTRUCTION COMPANY