If a 12 AWG TW copper conductor is connected to a new circuit breaker with a termination temperature limitation marked at 60/75°C, what is its ampacity?

The ampacity of a conductor is determined by factors including its size, insulation type, and the temperature rating of the termination point. In this case, the 12 AWG THHN (Thermoplastic High Heat-resistant Nylon-coated), also referred to as TW (Thermoplastic) for this specific classification, needs to be assessed in conjunction with its maximum allowable temperature.

The specified termination temperature limitation is 60/75°C, which is a common rating found on certain circuit breakers. According to the National Electrical Code (NEC), the ampacity for a 12 AWG copper conductor at these temperature ratings is 20 amps. This is derived from NEC Table 310.16, which outlines the maximum allowable current-carrying capacities (ampacity) for conductors based on their insulation type and installation conditions.

At 60°C, the ampacity is typically 20 amps for a 12 AWG copper conductor. The specification of the 75°C rating further supports this as it allows for the same rating of 20 amps or higher, but since both temperatures are being considered, the ampacity remains consistent in reference to standard values for a 12 AWG.

Thus, the correct answer is based on the assessment of conductor size,