Between a 2-pole, 20-amp circuit breaker and a load, 10 AWG 2-wire AC cable is installed. This circuit has a rating of ___ amps.

Between a 2-pole, 20-amp circuit breaker and a load, 10 AWG 2-wire AC cable is installed. This circuit has a rating of ___ amps.

• A. 30
• B. 20
• C. 35
• D. 25

Answer: (B)

The rating of a circuit is set by the protective device, with the conductor needing to be able to carry that current safely. A two-pole breaker rated at 20 amps protects both hot conductors on this circuit. The 10 AWG copper two-wire cable used here has an ampacity that is higher than 20 amps, so it can safely carry 20 amps without overheating. Because the breaker is the limiting factor, the circuit’s rating is 20 amps. If the breaker were larger than what the conductor could safely carry, you’d need a heavier gauge, but in this setup the protection device dictates the rating.

The rating of a circuit is set by the protective device, with the conductor needing to be able to carry that current safely. A two-pole breaker rated at 20 amps protects both hot conductors on this circuit. The 10 AWG copper two-wire cable used here has an ampacity that is higher than 20 amps, so it can safely carry 20 amps without overheating. Because the breaker is the limiting factor, the circuit’s rating is 20 amps. If the breaker were larger than what the conductor could safely carry, you’d need a heavier gauge, but in this setup the protection device dictates the rating.