12 gauge wire at a glance
| Diameter (bare copper) | 0.0808 in (2.05 mm) |
|---|---|
| Cross-section area | 3.31 mm² (6,530 circular mils) |
| Copper ampacity, 60°C / 75°C / 90°C | 20 / 25 / 30 A |
| Maximum breaker (copper) | 20 A |
| Aluminum ampacity, 60°C / 75°C / 90°C | 15 / 20 / 25 A |
14 AWG copper is limited to 15 A, 12 AWG to 20 A and 10 AWG to 30 A, and 12 and 10 AWG aluminum to 15 A and 25 A, by the overcurrent rules in NEC 240.4(D), even where the ampacity table lists more.
How far can 12 gauge wire run?
Current is only half the story. The wire loses voltage over distance, and the NEC recommends staying within 3%. This table gives the longest one-way run of 12 AWG copper within 3% drop, by current and voltage.
| Current | 12 V DC | 24 V DC | 120 V AC | 240 V AC |
|---|---|---|---|---|
| 10 A | 9.1 ft | 18 ft | 91 ft | 182 ft |
| 15 A | 6.1 ft | 12 ft | 61 ft | 121 ft |
| 20 A | 4.6 ft | 9.1 ft | 46 ft | 91 ft |
Use the voltage drop calculator for another size, current or limit. For 12 V runs by size, see the 12V wire gauge chart.
What 12 gauge wire is used for
- 20 A receptacle circuits in kitchens, bathrooms, garages and laundry rooms
- Dedicated circuits for microwaves, dishwashers and window AC units
- Long 15 A circuits where voltage drop calls for a size up
Cable type and the rules
12/2 and 12/3 NM-B (Romex) is the standard cable for 20 A circuits. Do not use 12 AWG aluminum on a 20 A breaker. It is limited to 15 A.
Neighboring sizes
| Gauge | Diameter | Copper amps (75°C, with NEC 240.4(D) limits) |
|---|---|---|
| 14 AWG | 0.0641 in | 15 A |
| 12 AWG | 0.0808 in | 20 A |
| 10 AWG | 0.1019 in | 30 A |
The wire gauge chart covers every size, and the amps per wire size table lists them in all three temperature columns.
Frequently asked questions
How many amps can 12 gauge wire handle?
20 amps for copper. The table lists 25 A at 75°C, but NEC 240.4(D) limits it to a 20 A breaker.
How many watts can 12 gauge wire handle?
2,400 W at 120 V (20 A), or 1,920 W for a continuous load. At 240 V it handles 4,800 W.
How far can 12 gauge wire run?
About 46 feet one way at 20 A and 120 V within 3% drop. At 10 A it doubles to about 91 feet.
What size breaker for 12 gauge wire?
A 20 amp breaker or smaller.