ADDN/ ALTN TO EARTHING PITS AND LIGHTENING ARRESTER AT AF STN BORJHAR UNDER GE (AF) BORJHAR

Amount

M&L for installation of Digital Grounding System with surge protection device with LCD display for communication equipment complete all as specified and directed. Note:- Any other items which are required for installation of DGS are deemed to be included in the quoted rate. Make - Ennob or Equivalent as approved by GE. Note:- Detail specifications of Digital Grounding System is attached as Annexure 'A' to BOQ.

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 by means of brass nut, bolt, washer & GI protection pipe for earth strip from the earthing plate to the DB/main switch/Panel, (40 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 C2 and pit cover made up of 40 mm thick pre cast RCC 1:2:4 type B1 reinforced with 6 mm dia TMT bar and suitable handle of 8 mm dia TMT bar including necessary earth work as shown in SSR Part-I, Plate No.5 as specified & directed. Note:- i) The copper strip and protection pipe beyond 7.5 m 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 & salt is deemed to be included in this rate v) During earth work if surface water found at site, the cost for dewatering through pump set is deemed to be included in this rate.

Taking out earth continuity conductor of any types or sizes from brick wall/ RCC structure/ CGI sheet or equivalent location carefully including 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 (where ever required) on any other indicated location for loop earthing etc with 20x3mm copper strip all as specified & directed. (Copper strips should be fixed on bridge insulator of 60 cm apart if reqd)

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 & directed. (Copper or Aluminium or GI strips should be fixed on bridge insulator of 60 cm apart if required) Note:- Cost of insulator, screw, nut & bolt is deemed to be included in the quoted rate

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

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

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

Supply, install, testing & 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 75 kg to maximum 100 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 m 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. 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 packed 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 & cost of the same is deemed to be included in the quoted rate ix) After connection to the earth strip, inspection pit shall be prepared & it shall be made up of PCC 1:3:6 type C1 and pit cover made up of 40 mm thick pre cast RCC 1:2:4 type B1 reinforced with 6 mm dia TMT rod and suitable handle of 8 mm dia TMT rod including necessary earth work complete. 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. Please refer Annexure 'A' to BOQ.

S&F single, pointed air termination copper rod (12mm dia and 300 mm long), as on galvalume/ CGI/ AC sheet/ RCC roof through copper flat, clamp, riveting & brazing works complete all as specified and directed.

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

M&L for charging magnesium sulphate mixing with water in earthing pit to improve the earth resistance all as specified and directed

Rajan Traders

M/S. SUBHAS CONSTRUCTION CO.