Ground wire size chart
A 20 amp circuit needs a 12 AWG copper ground wire, a 60 amp circuit 10 AWG, a 100 amp circuit 8 AWG and a 200 amp circuit 6 AWG copper. Aluminum ground wires are one or two sizes larger.
| Breaker up to | Copper | Aluminum |
|---|---|---|
| 15 A | 14 AWG | 12 AWG |
| 20 A | 12 AWG | 10 AWG |
| 60 A | 10 AWG | 8 AWG |
| 100 A | 8 AWG | 6 AWG |
| 200 A | 6 AWG | 4 AWG |
| 300 A | 4 AWG | 2 AWG |
| 400 A | 3 AWG | 1 AWG |
| 500 A | 2 AWG | 1/0 AWG |
| 600 A | 1 AWG | 2/0 AWG |
| 800 A | 1/0 AWG | 3/0 AWG |
| 1,000 A | 2/0 AWG | 4/0 AWG |
| 1,200 A | 3/0 AWG | 250 kcmil |
- Copper
- Aluminum
How to read the ground wire size chart
Find the first row at or above the breaker that protects the circuit. A 30 or 45 amp circuit uses the 60 A row. The ground wire never needs to be larger than the circuit's hot wires.
Ground wire on long runs
When the hot wires are made larger than ampacity requires, usually for voltage drop, the ground wire must grow in the same proportion of circular mils. For example, a 100 A copper feeder upsized from 3 AWG to 1/0 AWG needs a 4 AWG copper ground instead of 8 AWG. The wire size calculator does this automatically.