What is the ampacity of a 10 AWG THWN copper conductor when terminated to a circuit breaker with a maximum temperature of 60°C?

To determine the ampacity of a 10 AWG THWN copper conductor when terminated to a circuit breaker rated for a maximum temperature of 60°C, reference to the National Electrical Code (NEC) is necessary. Ampacity refers to the maximum amount of electric current a conductor or device can carry before sustaining immediate or progressive deterioration.

According to NEC Table 310.16, the ampacity of copper conductors is rated based on their temperature ratings. For a 10 AWG copper wire, the base ampacity at an ambient temperature of 30°C is typically listed as 30 amps when using THWN insulation.

However, for conductors operating at a higher maximum temperature rating, such as 60°C, the ampacity needs to be adjusted based on the circuit breaker and insulation ratings. In this case, even though the base ampacity is 30 A, since the breaker has a maximum termination temperature of 60°C, adjustments may lead to different considerations, but in this scenario, the ampacity remains at the nominal 30 A because THWN insulation effectively supports this rating without derating under typical conditions when referenced to the circuit breaker's limitations.

Therefore, the correct answer of 30 A reflects the established ampacity for a