The scope of work shall cover providing grounding stations, laying copper ground wires and connecting the panels, equipments, etc. to the ground grip as shown in the drawing.
Earth / Ground Station
The ground station shall be as shown in the drawing. The ground electrode shall be minimum 10 feet long 1 inch dia steel pipe with copper weld exterior surface. The ground resistance shall be maintained with a suitable soil treatment as shown on drawings or as discussed and decided at site.
The resistance of each ground shall not exceed 2 ohms.
The ground wire shall be fixed to the rod with a clamp and safety set screws. The clamp shall be permanently accessible. Manholes with proper covers shall be provided.
Ground connections shall be of the bolted type on the top of the rod.
Earthing / Grounding Wire and Connectors
- Grounding strip shall be of bare copper with minimum current carrying capacity in accordance with IEE wiring regulations.
- The complete grounding system shall be mechanically and electrically connected to provide an independent return part to the ground source.
- Where non metallic or flexible conduits or wiremold are used for all or part of a run other than to motors, a green color coded conductor shall accompany the circuit wiring. This conductor shall connect the ground bus or ground terminal in panel boards to the outlet or device ground lugs. For other grounding connections see equipment and outlet grounding section.
- In accessible connections shall be made by the exothermic process.
- Bolted connections shall be of the multiple bolt type. Bolts, washers and stop nuts shall be of high copper alloy, aluminium bronze or silicone bronze. Ferrous hardware will not be accepted.
- Where grounding terminal connectors are brazed to equipment, the metal shall be thoroughly cleaned prior to razing and impaired surfaces repainted to prevent corrosion.
- Where bare copper is jointed by bolting, contact surfaces shall be electro silver plated.
- Ground connector for connecting to a steel surface shall be of the bolted pressure type.
- Flat steel tongue shall have an offset with a seat and one durium or everdur ovalshank bolt, nut and lock washer for fastening cable, with bronze clamp.
- All grounding leads/wires shall be installed on suitable which will clear the strip off the wall or structure.
- All wires terminated on machines, panels or panel boards shall have suitable lugs and spring washers.
- All switch panels, panel boards, and other equipment shall be grounded with ground wires size shown on drawings.
Testing of Earthing / Grounding System
The entire installation shall be tested in accordance with IEE regulation and the following ground resistance values shall be recorded:
1. Grounding station (each).
2. Grounding system (as a whole).
The following are the recommended makes: