REPLACEMENT OF UNSERVICEABLE EARTHING WITH EARTH STRIP OF VARIOUS SIZES AT JETTY AREA AT NAVAL

Amount

M & L for casting Chemical earth pits with Pipe in Pipe technology 50 mm Cu bonded , 200 microns, 3 Mtr Long Earth Electrode targeted/ achieving individual earthpit result from 1.5 ohms upto maximum of 5.0 ohms for each individual pit and by maintaining of expected Grid value of 0.20 ohms but less than 0.5 ohm for grid earth pits as in around individual technical building with the following items, specifications and testing complete for each pit complete all as specified and directed. (i) Boring 300 mm dia of earth pit in soft and loose soil upto the depth of not less than 2.5 m deep below ground level by means of any method i.e boring/ digging including removal of excavated material to a distance of 50 m as directed by Engr-in-charge in each pit. (ii) Filling the each bore hole with 10 kg thick compacted layer of earth enhancing compound to reduce the soil resistivity as per Clause 14.5d of IEEE 80:2000 (latest Edition) of make Terec+ as per manufacturers specifications. (iii) Placing of 3 m length of 50mm dia of copper bonded pipe-in-pipe earth electrode with welded copper plate 38mmx200mm of 12mm thick on top. The earth rod should be placed at centre of each bore hole/earth pit with minimum of 10 kg inserted in to Terec+ layer

(iv) Back filling with earth enhancing compound up to earth pit GL to reduce the soil resistivity as per clause 14.5b of IEEE 80:2000 (latest Edition) of make Earthcon upto the ground. (v) Connecting/Jointing/brace welding each electrode of earth pit serially with copper earthing strip 25X3 mm with minimum 3 m distance between two earth pits buried below GL in trench filled with earth enhancing compound to reduce the soil resistivity as per Clause 14.5b of IEEE 80:2000 (latest edition) by enhancing its ionic properties, dispersion properties, hygroscopic properties, expansion properties, diffusion properties etc, incl earth excavation complete all as directed by Eng-in-charge. (vi) Placing 500X500X250 mm HDPE earth pit cover (IEC 62561-5) flushed with ground placed over 100mm thick PCC (1:3:6 Type I) of size 550 x 550 mm including required earth excavation, refilling and packing. The earth pit cover should be UV stabilized, lockable jam free lid, stackable design, resistant to substances including petrol oil, diesel, bitumen and concrete etc

vii) The quoted rate is deemed to be inclusive of necessary removal of excavated soil to a distance of 50 mtr as directed by the Engr-in-Charge. viii) Any other requirement if desired by the Engr-in-Charge as per site conditions shall be provided by the contractor without any extra cost. Note: a) The earth pits should have a minimum distance of 3m from each other and a minimum distance of 2m from building walls b) If grid value is found less than 0.5 ohms then the contractor will re-execute earth pits or put addl pit with no extra cost to the Govt.

M & L Aluminium strip 25 x 3.15mm with saddles and fixing screws etc. for roof conductors and down conductors above ground complete all as specified and directed.

M&L for fixing Galvasnized earth strip of size 32mm x 6 mm making drilled hole at both ends and fixing to electrical structure/equipment earth point / earth test point complete all as specified and directed.

M & L Air termination, single pointed, aluminium rod 12mm dia and 300mm long complete all as specified and directed by Eng-in-Charge.

M & L Test point terminal block made of gun metal or phosphorus bronze size 75x75x25mm drilled and screwed including 3 nos. 8mm dia 25mm long hex. head screw complete all as specified and directed by Eng-in-Charge.

M & L for Earthing complete with galvanised steel pipe electrode, 40mm bore, heavy grade, 2.5 mtr long buried directly and vertically in ground with top edge at ground level after making bore hole of size not less than 300 mm dia and 2.65 Mtr long using suitable mechanical drilling rig or mannually (for drilling near the specified location), connected with galvanised steel earthing strip 32x6mm all as shown in Plate No-2, connected to the earthing test point, concrete pit in PCC 1:3:6 type C-2with RCC precast pit cover slab 400mmx400mmx80mm with handle for lifting made out of 8mm dia MS rod, funnel, wiremesh, charcoal and salt in alternate 150mm thick layers around GI earth pipe, including necessary returning filling in & removal all as specified or indicated in SSR Part-I, including testing to achieve earth resistance value as per IS specification on completion. complete all as specified and directed.

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