What ambient temperature is used to find the ampacity of one 8 AWG THWN-2 copper conductor installed in free air?

The correct choice is associated with the standard temperature used when determining the ampacity of conductors. In this case, 30 degrees Celsius is the typical ambient temperature that codes and standards, such as the National Electrical Code (NEC), reference for evaluating the ampacity of electrical conductors in free air.

Ampacity, which is the maximum amount of electric current a conductor or device can carry before sustaining immediate or progressive deterioration, depends significantly on ambient temperature. At 30 degrees Celsius, the ampacity tables provide consistent and standardized values, ensuring safe and efficient electrical installations. If the temperature is higher or lower, adjustments would need to be made according to correction factors to account for the temperature difference from the standard. Thus, utilizing 30 degrees Celsius ensures reliable calculations for the conductor's capacity to handle electrical loads without overheating.