Electrician's Licensing Practice Exam

A breaker rated for which ampacity is typically used with a 12 AWG wire?

1. 10 amp

2. 15 amp

3. 20 amp

4. 30 amp

The correct answer is: 15 amp

A breaker rated for 15 amps is typically used with a 12 AWG wire due to the ampacity specifications set by the National Electrical Code (NEC). The NEC states that 12 AWG wire is rated to carry up to 20 amperes of continuous load, but for branch circuits, it is common practice to use a breaker that is rated lower than the wire's ampacity to ensure safety and prevent nuisance tripping. Using a 15 amp breaker with 12 AWG wire ensures that the circuit is properly protected while allowing for a bit of headroom in current capacity. This configuration minimizes the risk of overheating and potential fire hazards, particularly in residential wiring applications. It is important to note that while 20 amp breakers are permissible with 12 AWG wire, this can be less common in certain applications where safety and circuit design principles are prioritized. The 10 amp and 30 amp options are not ideal pairings for 12 AWG wire; a 10 amp breaker would underutilize the wire capacity, and a 30 amp breaker would exceed safe limits for the wire, potentially resulting in serious safety risks.