MasterElecWire size · NEC 2023
What size wire for 50 amps?
Why 6 AWG
Terminations matter here. Under 110.14(C), circuits of 100 A or less use the 60°C column unless the equipment is listed and identified for higher-temperature conductors. Above 100 A, the 75°C column applies.
| Size | 60°C | 75°C | Note |
|---|---|---|---|
| 8 AWG copper | 40 A | 50 A | Only with 75°C-rated terminations |
| 6 AWG copper | 55 A | 65 A | Works in either column |
When 8 AWG copper is allowed
8 AWG reaches 50 A in the 75°C column only. Use it only if the equipment at both ends is listed and identified for it. If you can't confirm that, use 6 AWG.
What about aluminum?
Use 4 AWG aluminum or copper-clad aluminum, rated 55 A at 60°C. 6 AWG aluminum reaches 50 A at 75°C only, under the same termination rule.
Ground wire
Table 250.122 gives a minimum 10 AWG copper equipment grounding conductor for a 50-amp breaker.
Long runs: check voltage drop
A 50 A load, 100 ft one way, on 240 V single-phase, with 6 AWG copper drops about 4.9 V, or 2.0%. Longer runs may need a larger wire.
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