National Physical Laboratory Tender

Supply & Installation of waterless and maintenance free chemical earthing with minimum 17 mm x 3 meter solid copper conductor electrode embedded in 85 mm dia of high purity electrically conductive granular, having ultra low resistivity of 0.001 Ohm per m. (Provide the resistivity certificate for the same). Electrode made of electrically conductive granular mixed with cement to pre cast or backfill the voids surrounding the copper conductor in augured bore hole of 100 mm dia x 3000 mm depth, resulting in increase of effective surface area of the earth electrode to acheive earth resistance value less than 01 ohm. In case of high soil resistivity a grid of multiple interconeected electrodes to be installed to lower the desired earth resistance value less than 01 Ohm with no further maintenance or periodic watering in all type of soil including dry or rocky soils (preferably not more than 06 nos electrodes for one sets of earthing pit as current experience at NPL hard rocky soil) complete in all respect as directed by engineer incharge. Make of electrically conductive granular should be Marconite/Intess/Earthonite or equavalent Note: 1. Contractor may visit the site before quoting the rates regarding testing of soil resistivity, soil condition or any other requirement since no additional payment will be made for the same. 2. Interconnection copper strips between the electrodes (appx 3.00 meter for two electrodes) will include in the work and will not be paid in copper strip measurement.

Pre-cast copper electrode min 17 mm dia X 3.0 meter length soid copper conducer embedded in 85 mm dia of high purity electrically conductive granular, having ultra low resistivity of 0.001 Ohm per m to acheive earth resistance value less than 01 ohm. Make of electrically conductive granular should be Marconite/Intess/Earthonite or equavalent

Supply and fixing of earth pit chamber cover made out from CI, size 300 mm X300 mm including all masonary work with making good the same as directed by engineer incharge.