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What size wire for 125 amps?
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1 AWG copper
minimum for 125 A (75 °C column, NEC 310.16) · 2/0 AWG aluminum
125 amp wire size by distance (3% voltage drop, copper)
| One-way distance | 120 V | 240 V |
|---|---|---|
| 25 ft | 1 AWG | 1 AWG |
| 50 ft | 1 AWG | 1 AWG |
| 75 ft | 1 AWG | 1 AWG |
| 100 ft | 1/0 AWG | 1 AWG |
| 125 ft | 2/0 AWG | 1 AWG |
| 150 ft | 3/0 AWG | 1 AWG |
| 200 ft | 4/0 AWG | 1/0 AWG |
| 250 ft | 250 kcmil | 2/0 AWG |
| 300 ft | 300 kcmil | 3/0 AWG |
Load assumed at the full 125 A. For continuous loads the circuit must be sized at 125% of the load (e.g. a 100 A continuous load on a 125 A breaker).
Check your exact run
FAQ
What size wire for a 125 amp circuit?
1 AWG copper or 2/0 AWG aluminum at 75 °C for short runs; longer runs need larger wire to limit voltage drop.
Can I use 1 AWG on a 125 amp breaker for 150 feet?
Check voltage drop: see the distance table on this page.
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