What is the ampacity of a single 8 AWG THWN-2 copper conductor installed in free air at an ambient temperature of 50°C?

To determine the ampacity of a single 8 AWG THWN-2 copper conductor installed in free air at an ambient temperature of 50°C, we first need to refer to the appropriate tables, such as the National Electrical Code (NEC) standards that list the ampacity values based on wire gauge, insulation type, installation method, and ambient temperature.

For a single copper conductor with an 8 AWG size, the standard ampacity in free air at a typical reference temperature (usually 30°C) is around 55 amps. However, since the installation temperature is 50°C, we need to consider the temperature correction factor.

As the ambient temperature increases, the ampacity of the conductor decreases due to the increased resistance and potential overheating. For THWN-2 insulation, the temperature rating allows us to perform adjustments based on the higher ambient temperature.

In tables adjusted for temperature, typical ampacity values indicate a reduction at the increased temperature. The adjustment can lead to the figure around 66 amps for a conductor rated at the higher temperature of 50°C.

Given that ampacities are often rounded to whole numbers in practical applications and tables, the 66 amps would usually be presented as being close to the correct range