Wire & breaker size chart
NEC wire gauge and breaker sizing at a glance — the right breaker and copper wire for common loads, plus conductor ampacity by AWG.
Breaker & wire by common load
| Breaker | NM-B cable (Romex) | Conduit / SER (75°C) | Typical use |
|---|---|---|---|
| 15 A | 14 AWG | 14 AWG | Lighting, general outlets |
| 20 A | 12 AWG | 12 AWG | Kitchen, bath, garage outlets |
| 30 A | 10 AWG | 10 AWG | Electric dryer, water heater |
| 40 A | 8 AWG | 8 AWG | Electric range, 32A EV charger |
| 50 A | 6 AWG | 8 AWG | Range, 40A EV charger, NEMA 14-50 |
| 60 A | 4 AWG | 6 AWG | 48A EV charger, subpanel feed |
| 70 A | — | 4 AWG | Large subpanel, heat pump |
| 80 A | — | 4 AWG | Subpanel, 64A EV charging |
| 90 A | — | 3 AWG | Subpanel feeder |
| 100 A | — | 3 AWG | Subpanel, small service |
| 125 A | — | 1 AWG | Large subpanel |
| 200 A | — | 2/0 AWG | Main dwelling service (NEC 310.12) |
Two columns because the wiring method decides the answer. Most residential branch circuits are NM-B cable, and NEC 334.80 requires NM cable ampacity to be taken from the 60°C column even though the conductors carry 90°C insulation — which forces a larger conductor at 50 A and above. Runs in conduit (THHN/THWN-2) or SER cable use the 75°C column, assuming 75°C-rated terminations (NEC 110.14(C)). A dash means NM-B is not normally used at that size.
Copper conductor ampacity (NEC 310.16)
| Wire (AWG) | 60°C | 75°C | 90°C | Max breaker |
|---|---|---|---|---|
| 14 AWG | 15 A | 20 A | 25 A | 15 A |
| 12 AWG | 20 A | 25 A | 30 A | 20 A |
| 10 AWG | 30 A | 35 A | 40 A | 30 A |
| 8 AWG | 40 A | 50 A | 55 A | — |
| 6 AWG | 55 A | 65 A | 75 A | — |
| 4 AWG | 70 A | 85 A | 95 A | — |
| 3 AWG | 85 A | 100 A | 115 A | — |
| 2 AWG | 95 A | 115 A | 130 A | — |
| 1 AWG | 110 A | 130 A | 145 A | — |
| 1/0 AWG | 125 A | 150 A | 170 A | — |
| 2/0 AWG | 145 A | 175 A | 195 A | — |
| 3/0 AWG | 165 A | 200 A | 225 A | — |
| 4/0 AWG | 195 A | 230 A | 260 A | — |
How sizing works
- Continuous loads (such as EV charging) require the circuit and overcurrent device at 125% of the load — NEC 625.41 and 210.20(A).
- Wire here assumes 75°C-rated terminations per NEC 110.14(C). 60°C terminations, long runs (voltage drop), or aluminum conductors need upsizing.
- 14, 12, and 10 AWG have small-conductor overcurrent limits under NEC 240.4(D) — see the Max breaker column.
- Always confirm sizing with a licensed electrician and your local authority having jurisdiction (AHJ).