Special repair to earthing infra and lightening arrester to improve high earth to neutral (E-N) voltage at 14 BRD under GE (AF) Borjhar

M&L for earthing complete with copper earth plate electrode 600x600x3.15 mm thick buried directly in ground (earth pit not less than 2.25 m depth below ground level) with top edge of the plate not less than 1.5 m below normal ground level connected to copper strip 20x3mm mm dia by means of brass nut, bolt, washer& protection pipe for earth lead from the earthing plate to the DB/main switch/Panel, (25 mm bore, Light grade), watering pipe from plate to earthing pit (20 mm bore, medium grade), funnel with wiremesh. The earthing pit made up of PCC 1:3:6 type CI and pit cover made up of 40 mm thick pre cast RCC 1:2:4 type BI reinforced with 8 mm dia TMT rod and suitable handle of 10 mm dia TMT rod incl necessary earth work as shown in SSR Part 1 plate no.5 as specified & directed. Contd....

Note: i) The copper strip and protection pipe beyond 7.5 m length shall be measured and paid separately. However, earthwork and PCC work for the same is deemed to be included in this rate. ii) The desired value of earth resistance should be less than 1 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 & salt is deemed to be included in this rate iv) 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 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 all as specified and directed.

M&L for Copper strip 20 x 3.15mm with saddles and fixing screws etc. for roof conductors and down conductors above ground.

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

M&L for PCC as in foundation or any other works type B1 (1:2:4) (20mm graded aggregate) all as specified and directed. Note : Any form work required for PCC works are deemed to be included in this rate.

M&L for Plastering/ Rendering 10mm thick on fair faces of brick work or concrete surfaces cement sand type (1:3 ) all as specified and directed.

M&L for Air termination, single pointed, copper rod 12mm dia and 300mm long.

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

M & L for earth continuity conductor or main earthing lead fixed to wall / roof by dmc insulator (as reqd basis) on any other indicated location for loop earthing etc with 20x3mm copper strip all as specified & directed. (Copper strips should be fixed on cleat insulator of 60 cm apart if reqd)

M & L for earth continuity conductor or main earthing lead fixed to wall / roof by dmc insulator (as reqd basis) on any other indicated location for loop earthing etc with 32x6mm copper strip all as specified & directed. (Copper strips should be fixed on cleat insulator of 60 cm apart if reqd)

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

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

S&F galvanized steel tubes of 50 mm bore light grade including all fittings like bend & socket and fixed on walls / ceilings / floors throgh MS clamp for earth strip protection complete all as specified and directed.

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

Taking out old corroded electrode of any types or sizes from maintenance free chemical earthing.

Supply, install, testing & commissioning of maintenance free chemical earthing by pure Copper Electrode of 16 mm 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. Make- Electrode - 99.9% pure copper rod with test certificate for purity from any Government lab, Ground Enhancing Compound-ABB/ OBO The process for the earthing are appended 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 300 mm (minimum) dia to a depth of 3450 mm (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. v) 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. vi) A layer of 150mm of the above ground enhancing materials shall be prepared at the bottom. vii) Plastic sleeves from electrode shall be removed before it is lowered in the pit. viii) 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. Contd...

ix) 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 & cost of the same is deemed to be included in this rate x) After connection to the earth strip,inspection pit shall be prepared & it shall be made up of PCC 1:3:6 type CI and pit cover made up of 40 mm thick pre cast RCC 1:2:4 type BI reinforced with 6 mm dia TMT rod and suitable handle of 8 mm dia TMT rod incl necessary 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. xi) A coat of conductive petroleum jelly shall be applied on the terminal of the electrode & copper alloy clamp for protection against corrosion. xii) 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. Contd...

Note: i) If more than one earthing is reqd 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 1 Ω & after testing in presence of the rep of the Engr-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 prepartion of new earthing inspection pit made up of PCC 1:3:6 type CI and pit cover made up of 40 mm thick pre cast RCC 1:2:4 type BI reinforced with 8 mm dia TMT rod and suitable handle of 10 mm dia TMT rod (incl necessary earth work, demolition and removal of old damage inspection pit) as shown in SSR Part 1 plate no.5 or IS 3043:1987 complete all as specified & directed.

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 directed.

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