Special repair/replacement of existing earthing pits at 14 BRD AF and 33 MCU under GE(AF) Borjhar

Amount

M&L for earthing copper earth plate electrode of size 900 x 600 x 5mm thick with charcoal and salt and treating the surrounding soil with magnesium sulphate, buried directly in ground (earth pit not less than 2.4m depth below ground level) with top edge of the plate not less than 1.5m below normal ground level connected to copper strip 50 x 6mm dia by means of brass nuts, bolts, washer and protection pipe for earth strip from the earthing plate to the equipment/ test point/ panel, (GI pipe 80mm bore, Light grade), watering pipe from plate to earthing pit (GI pipe 20mm bore, medium grade), funnel with wiremesh. The earthing pit made up of PCC (1:3:6) type C-I (using 20mm graded stone aggregate) and pit cover, made up of 40mm thick pre cast RCC (1:2:4) type B-I (using 20mm graded stone stone aggregate) reinforced with 6mm dia TMT bars and suitable handle of 8mm dia TMT bars including necessary excavation and earth work complete all as shown in SSR Part-I Plate No. and as specified and as as directed.

Note: (i) The copper strip and protection pipe beyond 7.5m length shall be measured and paid separately. However, earthwork for the same is deemed to be included in this rate. (ii) Chemical like magensium sulphate of minimum quantity 150 kg for treatment of surrounding soil is deemed to be included in this rate. (iii) The desired value of earth resistance is less than 2 Ω, on testing after completion if the desired earth resistance is not obtained; the earthing will be redone at no extra cost, otherwise it will not be measured and paid to the contractor. (iv) The approx size of earth work for chemical treatment of soil and earthing is 2.4m x 1.5m x 0.6m (D x L x W) and form work of size1.2m x 0.9m x 0.6m for pouring charcoal & salt are deemed to be included in quoted rate. (v) During earth work if surface water found at site, No extra cost for dewatering through pumpset is admissible but at his own cost.

M&L for earthing copper earth plate electrode of size 900 x 600 x 5mm thick with charcoal and salt and treating the surrounding soil with magnesium sulphate, buried directly in ground (earth pit not less than 2.4m depth below ground level) with top edge of the plate not less than 1.5m below normal ground level, connected to copper strip of size 32x6mm mm dia by means of brass nuts, bolts, washers and protection pipe for earth strip from the earthing plate to the equipment/ test point/ panel, (GI pipe 50mm bore, light grade), watering pipe from plate to earthing pit (GI pipe 20mm bore, medium grade), funnel with wiremesh. The earthing pit made up of PCC 1:3:6 type C-I (using 20mm graded stone aggregate) and pit cover made up of 40mm thick pre cast RCC (1:2:4) type B-I (using 20mm graded stone aggregate) reinforced with 6mm dia TMT bar and suitable handle of 8mm dia TMT bar including necessary excavation and earth work complete all as shown in SSR Part-I Plate No. and as specified and as directed.

Notes: (i) The copper strip and protection pipe beyond 7.5m length shall be measured and paid separately. However, earthwork for the same is deemed to be included in this rate. (ii) Chemical like magensium sulphate of minimum quantity 150 kg for treatment of surrounding soil is deemed to be included in this rate. (iii) The desired value of earth resistance is less than 2 Ω, on testing after completion if the desired earth resistance is not obtained; the earthing will be redone at no extra cost, otherwise it will not be measured and paid to the contractor. (iv) The approx size of earth work for chemical treatment of soil and earthing is 2.4m x 1.5m x 0.6m (D x L x W) and form work of size1.2m x 0.9m x 0.6m for pouring charcoal & salt are deemed to be included in the quoted rate (v) During earth work if surface water found at site, No extra cost is admissible for dewatering through pumpset but at his own cost.

M&L for earthing complete with copper earth plate electrode of size 600 x 600 x 3.15mm thick burried directly in ground (earth pit not less than 2.25m depth below ground level) with top edge of the plate not less than 1.5m below normal ground level, connected to copper strip of size 20 x 3mm dia by means of brass nut, bolt, washer and protection pipe for earth wire from the earthing plate to the DB/main switch/panel, etc.(GI pipe 40mm bore, light grade), watering pipe from plate to earthing pit (GI pipe 20mm bore, medium grade), funnel with wiremesh. The earthing pit made up of PCC (1:3:6) type C-I (using 20mm graded stone aggregate) and pit cover made up of 40mm thick in pre cast RCC (1:2:4) type B-I (using 20mm graded stone aggregate) reinforced with 6mm dia TMT bar and suitable handle of 8mm dia TMT bar including necessary excavation and earth work all as shown in SSR Part-I, Plate No.5 complete all as specified and as directed.

Notes : (i) The copper strip and protection pipe beyond 7.5m length shall be measured and paid separately. However, earthwork for the same is deemed to be included in this rate. (ii) The desired value of earth resistance is less than 5 Ω, on testing after completion if the desired earth resistance is not obtained; the earthing will be redone at no extra cost, otherwise it will not be measured and paid to the contractor. (iii) Form work of size 0.9m x 0.9m x 0.6m for pouring charcoal and salt is deemed to be included in this rate (v) During earth work if surface water found at site, No extra cost is admissible for dewatering through pumpset but at his own cost.

Taking out carefully old corroded earth continuity conductor of any types and sizes from brick wall/ RCC structure/CGI sheet or equivalent location including making good to disturbed surfaces complete all as specified and as directed.

M&L for earth continuity conductor or main earthing lead fixed to wall / roof by DMC insulator (as required basis) on any other indicated location for loop earthing, etc. with 20 x 3mm copper strip complete all as specified and as directed. Note : Copper strips shall be fixed on bridge insulator of 60cm apart as required.

M&L for earth continuity conductor or main earthing lead fixed to wall / roof by DMC insulator (as required basis) on any other indicated location for loop earthing etc. with 32 x 6mm copper strip complete all as specified and as directed. Note : Copper strips shall be fixed on bridge insulator of 60cm apart as required.

M&L earth continuity conductor or main earthing lead fixed to wall / roof by DMC insulator (as required basis) on any other indicated location for loop earthing etc. with 50 x 6mm copper strip complete all as specified and as directed. Note : Copper strips shall be fixed on bridge insulator of 60cm apart as required.

M&L for re-fixing of old earth continuity conductor or main earthing lead of any types or sizes (Copper or Aluminium or GI) to wall / roof by dmc insulator (as required basis) on any other indicated location for loop earthing, etc. complete all as specified and as directed. Note : (i) Copper/Aluminium or GI strips shall be fixed on bridge insulator of 60cm apart as required. (ii) The cost for insulators, screws, nuts & bolts, etc.are to be inclussive with the quoted rate.

Taking out carefully old corroded steel tubes of any types or sizes from brick wall/ RCC structure/ CGI sheet or equivalent location including making good to the disturbed surfaces complete all as specified and as directed.

S&F galvanized steel tubes of size 40mm bore, light grade, including all fittings like bend, socket, etc. and fixed on walls/ceilings/floors, etc. through MS clamp for earth strip protection complete all as specified and as directed.

All as per Serial item No. 10 here-in-before but 50mm bore

All as per Serial item No. 10 here-in-before but 80mm bore

M&L for clamped joints (by overlapping the bars and applying clamps around the overlap) after brazing the jointing portion of the copper earthing strips complete all as specified and as directed.

M&L for test point terminal block made of gun metal for phosphorous bronze of size 75 x 75 x 25mm, drilled and screwed including 3 Nos. 8mm dia with 25mm long hex head screw within halogen free weather proof IP-66 enclosure with one/ two nos mounting bracket complete all as specified and as directed. Make (Enclosure) : Hensel/ OBO Note : The test point should be 1.0m above ground level.

M&L for excavating in bore holes of 300mm (minimum) dia to a depth of 3450mm (minimum) by augur or any other process in trenches manually not exceeding 0.5 cum in each bore including removing surplus excavating material, returning, filling in, etc. in soft/loose soil complete all as specified and as directed.

Taking out old corroded electrode of any types or sizes from maintenance free chemical earthing complete all as specified anad as directed.

Supply, installation, testing and commissioning of maintenance free chemical earthing by pure Copper Electrode of 17.2mm dia and 3000mm long for earthing with excellent electrical conductivity and corrosion resistance, minimum 50 kg ground enhancing compound/ material used around the electrode inside the earth pit to define the working environment of the earthing system complete all as specified and as directed. Note : Electrode - 99.9% pure copper rod with test certificate for purity from any Government Lab, Ground Enhancing Compound Make : ABB/OBO/Ennov/True Power

The process for the earthing is appended as below:- (i) Soil resistivity of that area shall be measured. (ii) If soil resistivity is more, then multiple earthing shall be carried out in grid pattern i.e if two earthing is reqd then the pattern is" ── " and if three earthing is reqd the the pattern is "∆", but a minimum distance of 2 meters between two earth pit should be maintained. However, there should not be more than three earthing pit in a grid. (iii) Make a bore of 300mm (minimum) dia to a depth of 3450mm (minimum) by augur or any other process. (iv) The soil dug out from the earth pit shall be checked to remove lumps and stones from it, before back filling. (iv) Moisture retaining ground enhancing materials of minimum 50 kg having resistivity equal to or less than 0.3 Ωm shall be poured in the bore. (v) A layer of 150mm of the above ground enhancing materials shall be prepared at the bottom. (vi) Plastic sleeves from electrode shall be removed before it is lowered in the pit. (vii) Small quantity of ground enhancing material shall be filled at a time and some water in the pit. Further quantity shall be added after the earlier quantity has been sufficiently poked with suitable rod to remove trapped air bubbles from it.

(viii) If grid earthing is reqd. necessary interconnection shall be carried out by 20x3mm copper strip which shall be buried below 300mm from G.L with additional quantity of ground enhancing material and cost of the same is deemed to be included in this rate (ix) After connection to the earth strip,inspection pit shall be prepared & it shall be made up of PCC (1:3:6) type C-I (using 20mm graded stone aggregate) and pit cover made up of 40 mm thick pre cast RCC (1:2:4) type B-I (using 20mm graded stone aggregate) reinforced with 6mm dia TMT bar and suitable handle of 8mm dia TMT bar including necessary excavation and earth work complete all as shown in diagram. There shall be provision of hole of 300mm dia for easy termination of strip, pouring normal water during hot summer seasons. (x) A coat of conductive petroleum jelly shall be applied on the terminal of the electrode & copper alloy clamp for protection against corrosion. (xi) A certificate from the Government Lab for purity of the electrode and resistivity of ground enhancing compound /material shall be furnished prior approval of sample.

Notes :- (i) If more than one earthing is required due to high soil resistivity at site the payment shall be carried out by measuring extra quantity (ii) The strip for grid earthing/ connetion strip for Test Point shall be measured & paid separately (iii) The cost for excavation,returning filling in & removing of soil shall be measured & paid in the item as mentioned below, however form work if reqd is deemed to be included in this rate (iv) The desired value of earth resistance should be less than 2 Ω & after testing in presence of the rep of the Engineer-in-Charge, if the earth resistance value is not obtained, the earthing will be redone at no extra cost, otherwise it will not be measured and paid to the contractor. (v) The quantity of ground enhancing material as mentioned above is tentative, due to site condition if additional quantity of ground enhancing materials are reqd, the contractor is bound to provide additional quantiy without demanding extra payment for the same from the department. However, the maximum quantity of ground enhancing materials used for chemical earthing pit and grid connections are 75 kg. (vi) During earth work if surface water found at site, the cost for dewatering through pumpset is deemed to be included in this rate.

M&L for charging common salt with mixing water in earthing pit to improve the earth resistance complete all as specified and as directed.

M.S. Construction