The two standard earthing strip materials are galvanised iron (GI) and copper. Copper carries more fault current per size, resists corrosion and lasts the life of the installation; GI costs less and suits general LT earthing. IS 3043 sets minimum sizes and lets both be used provided the conductor survives the fault current without exceeding its temperature limit.
What the standards require
- IS 3043 sizes the conductor to the fault current and clearing time, and sets minimum cross-sections for buried strip.
- IEEE 80 uses the same adiabatic basis with material factors (about 205 for copper, 80 for steel).
- Buried GI needs a larger section than copper for the same duty, plus margin for corrosion.
- Joints must not create a bimetallic couple - match the strip, lugs and electrode metals.
Choosing the material
| Use case | Material |
|---|---|
| Substations, HV, data centres | Copper |
| Lightning down-conductors | Copper |
| General LT earthing on a budget | GI |
| Corrosive or coastal soil | Copper or copper bonded |
