What is the ampacity of a 10 AWG THWN copper conductor connected to a circuit breaker with a maximum termination temperature of 60 degrees Celsius?

The ampacity of a conductor is determined by its size (gauge), the material it's made from (copper or aluminum), and the environment in which it is installed, including the maximum termination temperature. For a 10 AWG THWN (Thermoplastic Heat and Water Resistant Nylon) copper conductor, tables from the National Electrical Code (NEC) indicate the maximum allowable current-carrying capacity.

In this case, the conductor is rated for 30 amperes when used at a termination temperature of 60 degrees Celsius. This rating takes into account the fact that copper has good conductive properties and the insulation type (THWN) is suitable for wet or dry locations. At this specific ampacity, the conductor can safely carry the current without exceeding its temperature ratings under normal operating conditions.

Therefore, for a 10 AWG copper conductor with a maximum termination temperature of 60 degrees Celsius, the correct ampacity is indeed 30 A.