10-gauge wire“Twelve-gauge wire is good for 20 amps, 10-gauge wire is good for 30 amps, 8-gauge is good for 40 amps, and 6-gauge is good for 55 amps,” and “The circuit breaker or fuse is always sized to protect the conductor [wire].”
Can You Use a 30-Amp Breaker On 12-Gauge Wire? You should not use a 30-amp circuit breaker on a 12-gauge wire. The circuit breaker installed on a circuit is of a specific size to protect a certain wire gauge. A larger breaker on a thinner wire will allow more current over the wire before tripping.
Yes, based on the National Electric Code or NEC, you can use 12-2 AWG cables for THHN or THWN-rated wires. These cables are made for general purposes and can hold up to 194 degrees without taking any damage. It simply means these wires can withstand the heat temperature drawn by a 30 amp circuit breaker.