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Recommended AWG (minimum)
AWG Wire Gauge Reference (NEC 310.16, 60°C)
| AWG | Copper Amps | Aluminum Amps | Common Uses |
|---|---|---|---|
| 14 AWG | 15A | N/A | Lighting, outlets (15A circuit) |
| 12 AWG | 20A | 15A | Kitchen, bathroom outlets (20A) |
| 10 AWG | 30A | 25A | Dryers, A/C units |
| 8 AWG | 40A | 30A | Electric ranges, large A/C |
| 6 AWG | 55A | 40A | Sub-panels, EV chargers |
| 4 AWG | 70A | 55A | Large sub-panels |
| 2 AWG | 95A | 75A | Main service, large sub-panels |
| 1/0 AWG | 125A | 100A | 100-125A sub-panels |
| 2/0 AWG | 145A | 115A | 150A sub-panels |
| 3/0 AWG | 165A | 130A | Large sub-panels |
| 4/0 AWG | 195A | 150A | 200A service entrance |
How to Choose the Right Wire Size
Wire gauge affects two things: safety and voltage drop. Using too small a wire creates a fire hazard as the wire overheats. Too large a wire wastes money. The NEC specifies minimum wire sizes for circuit breaker ratings — but long runs require you to upsize wire to keep voltage drop under 3%.
This calculator uses the circular mils formula to determine the minimum wire size that keeps voltage drop within acceptable limits while meeting the amp rating requirement. Always use the larger of the two requirements (ampacity vs. voltage drop).
⚠️ Temperature & Conduit Derating: These ratings assume ambient temperature of 86°F (30°C) or below and no more than 3 current-carrying conductors in a raceway. For hot environments (attics, outdoor conduit in sunlight), wire must be upsized per NEC 310.15(B)(1). For 4+ conductors in conduit, ampacity must be reduced per NEC 310.15(C)(1). Consult a licensed electrician for these conditions.
Always Confirm with a Licensed Electrician
This tool provides guidance for planning purposes. All electrical work should be performed by or reviewed by a licensed electrician and must comply with local codes and the current NEC edition.