The earthing conductor is the link between your equipment and the earth pit. If it is too small, badly joined or corroded, the best electrode in the world will not protect anyone. This guide covers the common choices on Indian sites and what decides their size.
Strip, wire or cable?
- Strip (G.I or copper): the usual choice for main earth runs from panels to pits, for earth grids, and for down conductors in lightning protection. It is easy to fix flat against walls and to bolt at joints.
- Wire (G.I or copper, sized by SWG): common for smaller equipment and domestic earthing.
- Flexible copper cable: for connections that must bend or move, such as motors on rails, doors of panels, and equipment that vibrates. Our flexible copper cable runs from 6 to 95 sq mm.
G.I or copper?
| G.I | Copper | |
|---|---|---|
| Conductivity | Lower | Much higher |
| Size for the same fault current | Larger | Smaller |
| Corrosion resistance | Good while the zinc lasts | Very good |
| Cost | Lower | Higher |
| Typical use | Most building and industrial runs | Substations, critical sites, corrosive ground, copper electrodes |
G.I strip is the most common earthing conductor in India because it is economical and robust. Copper is chosen where the conductor must be smaller for the same duty, where the ground is corrosive, or where it connects to copper or copper bonded electrodes and plates.
What decides the size
An earthing conductor must carry the largest fault current it could see, for as long as the protective device takes to clear it, without overheating. IS 3043 gives the method: the designer takes the fault current and clearing time, and the material’s properties, and works out the minimum cross-section. Copper needs a smaller section than G.I for the same duty. On top of that, designers add an allowance for corrosion and for mechanical strength, especially for conductors buried in the ground.
So the right size is not a rule of thumb; it comes from the fault level at that point in the installation. Ask your designer or consultant for it, and check that the strip size on the drawing matches the BOQ.
Sizes we supply
- G.I and copper strip: 25, 32, 40, 50 and 75 mm wide, 2 to 6 mm thick, in coils or cut lengths.
- G.I and copper wire: 4, 6, 8, 10 and 16 SWG.
- Flexible copper cable: 6 to 95 sq mm.
Strip and wire are sold by weight, which makes estimating awkward. Our material calculator converts length and size into kilograms for G.I, copper and aluminium.
Joints and fixing
- Make joints with bolts and washers of suitable material, or by welding where specified, and protect them from moisture.
- Avoid joining copper and G.I directly; use brass or stainless steel clamps, and keep such joints accessible.
- Fix strips firmly with saddles at regular intervals, so they cannot be pulled loose.
- Protect conductors where they pass through floors or walls, or could be damaged by vehicles.
Frequently asked questions
Which wire is used for earthing in a house?
Inside the house, the earth conductor is part of the wiring: an insulated copper wire, coloured green or green and yellow, running to every socket and appliance. From the main earth terminal to the earth pit, G.I or copper wire or strip is used, sized by the electrician for the supply.
Can aluminium be used for earthing?
Aluminium is not suitable for burying in the ground, where it corrodes. Where a design uses aluminium earthing conductors, they are kept above ground and connected to copper or G.I below ground with suitable joints.
Is a bigger strip always better?
It must be at least the size the fault calculation requires. A larger size adds a margin against corrosion and damage, but also adds cost; the designer balances the two.
Our earlier guide comparing electrode materials explains why keeping metals compatible matters. For material to your drawing, send us the BOQ.