What is the ampacity of two 8 AWG THWN-2 copper conductors installed in rigid metal conduit at an ambient temperature of 95 degrees F?

To determine the ampacity of two 8 AWG THWN-2 copper conductors installed in rigid metal conduit at an ambient temperature of 95 degrees Fahrenheit, it is essential to reference the appropriate National Electrical Code (NEC) tables and consider the effects of temperature on conductor rating.

According to the NEC, for 8 AWG copper conductors using the THWN-2 insulation type, the base ampacity is typically listed around 50-60 amps for single conductors at an ambient temperature of 86 degrees Fahrenheit. When the ambient temperature rises to 95 degrees Fahrenheit, as stated in the question, there is a need to apply a derating factor.

For THWN-2 conductors, which can withstand higher temperatures, there is a specified derating percentage for installations in conduit due to the reduced heat dissipation capability. The NEC allows for adjustments based on the number of conductors, ambient temperature, and installation method. In this specific case, since two conductors are used, there may be minimal derating.

Given the initial ampacity rating and after considering the temperature adjustment, the ampacity for the two 8 AWG THWN-2 copper conductors at an ambient temperature of 95 F yields an ampacity