What wire size should you use with a 30 amp breaker?

Answer 1

No! The minimum wire size allowable is 10 gauge for a 30 amp circuit. Don't risk the chance of an inner wall fire because too small of a wire gauge was used. Never shortcut anything to do with electrical wiring. Never.

Answer 2

Yes, a #8 wire is rated at 45 amps. One of the duties of a breaker is to protect the wire from over current. A 30 amp breaker will trip before reaching 45 amps so the wire will never get close to its rating.

Answer 3

A breaker is used to protect the conductor that is connected to it. A #14 copper conductor with an insulation factor of 90 degrees C is rated at 15 amps. So you see in this situation, the breaker is too large to protect the size of wire that you stated.

There is one occasion where the breaker can be larger than the wire size capacity. That is on motor load connections. A motor on start up can draw 300% of its nameplate amperage rating. To stop needless tripping every time the motor start, the electrical code allows a breaker to be rated at 250 % of the motors name plate rating..

For example if a motor draws 10 amp running current, the proper size breaker will be 10 x 250% = 25 amps. As there is no wire rated for 25 amps the next largest size would be #10. A #10 copper conductor with an insulation factor of 90 degrees C is rated at 30 amps.

Answer 4

12 gauge wire is required to be protected with a 20 amp max breaker. 10 gauge is required for a 30 amp breaker.