Wire ampacity chart (NEC Table 310.16)
These are the current ratings in amps for insulated copper and aluminum conductors in a raceway or cable, at 30°C ambient, with up to three current-carrying conductors. The column is the temperature rating of the insulation and of the terminals it connects to.
| AWG | Cu 60°C | Cu 75°C | Cu 90°C | Al 60°C | Al 75°C | Al 90°C | Max breaker (Cu, 75°C) |
|---|---|---|---|---|---|---|---|
| 14 | 15 | 20 | 25 | n/a | n/a | n/a | 15 A |
| 12 | 20 | 25 | 30 | 15 | 20 | 25 | 20 A |
| 10 | 30 | 35 | 40 | 25 | 30 | 35 | 30 A |
| 8 | 40 | 50 | 55 | 30 | 40 | 45 | 50 A |
| 6 | 55 | 65 | 75 | 40 | 50 | 55 | 60 A |
| 4 | 70 | 85 | 95 | 55 | 65 | 75 | 80 A |
| 3 | 85 | 100 | 115 | 65 | 75 | 85 | 100 A |
| 2 | 95 | 115 | 130 | 75 | 90 | 100 | 110 A |
| 1 | 110 | 130 | 145 | 85 | 100 | 110 | 125 A |
| 1/0 | 125 | 150 | 170 | 100 | 120 | 135 | 150 A |
| 2/0 | 145 | 175 | 195 | 115 | 135 | 150 | 175 A |
| 3/0 | 165 | 200 | 225 | 130 | 155 | 175 | 200 A |
| 4/0 | 195 | 230 | 260 | 150 | 180 | 205 | 225 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.
Which column do you use?
- 60°C for NM-B (Romex) cable. Its conductors are rated 90°C, but NEC 334.80 limits the ampacity to the 60°C column.
- 75°C for most breakers, panels and equipment terminals above 100 A, and for 100 A and smaller equipment marked 75°C. This is the column the wire size calculator uses.
- 90°C only as the starting point for derating, such as bundled conductors or a hot attic. The final ampacity cannot exceed the lower of the wire and terminal ratings.
Circuits of 100 A or less are treated as 60°C terminal circuits unless the equipment is marked for 75°C (NEC 110.14(C)). Most modern breakers are.
Rules of thumb that match the table
| Breaker | Copper wire | Usual use |
|---|---|---|
| 15 A | 14 AWG | Lighting |
| 20 A | 12 AWG | Receptacles |
| 30 A | 10 AWG | Dryer, water heater |
| 40 A | 8 AWG | Small range |
| 50 A | 8 AWG (6 AWG NM-B) | Range, EV charger |
| 60 A | 6 AWG (4 AWG NM-B) | Sub panel |
Where the breaker and wire are not an exact match, NEC 240.4(B) lets you use the next standard breaker above the wire's ampacity in some cases, but not on circuits feeding more than one cord-and-plug receptacle. For the reverse lookup, see the breaker to wire size chart. For long runs, check the voltage drop calculator too, because ampacity does not account for it.
Frequently asked questions
How many amps can 12 gauge wire handle?
20 amps. The table lists 25 A at 75°C, but NEC 240.4(D) limits 12 AWG copper to a 20 A breaker.
How many amps can 10 gauge wire handle?
30 amps for copper. Aluminum 10 AWG is limited to 25 A.
How many amps can 8 gauge wire handle?
40 amps at 60°C, 50 amps at 75°C and 55 amps at 90°C for copper.
How many amps can 6 gauge wire handle?
55 A at 60°C, 65 A at 75°C and 75 A at 90°C for copper, so it fits a 60 A breaker with 75°C terminals.