For a group of thirty-two 12 AWG THHN copper conductors installed at 45°C, what is the final ampacity of each conductor?

To find the final ampacity of each conductor, it's important to first understand how temperature affects the ampacity of a conductor, especially when looking at 12 AWG THHN copper conductors. The base ampacity values are usually given at a standard temperature of 30°C.

At higher temperatures, the ampacity decreases due to increased resistance in the conductors. When the operating temperature is stated as 45°C, it signifies that the conductors are subjected to a temperature that exceeds the standard. Typically, ampacity tables provide a correction factor that can be applied to adjust the base ampacity based on the ambient temperature.

For 12 AWG copper conductors, at 30°C, the ampacity is generally listed around 20 A. However, when applying a correction factor for the temperature increase to 45°C, you will find that the ampacity drops. Calculating this correctly involves applying the appropriate temperature correction factor, which reflects how much the capacity decreases as the temperature rises.

Using the common correction factor for the temperature increase from 30°C to 45°C, the calculation would typically yield around 10.44 A for each conductor based on the expected derating due to the elevated temperature.

In summary, the final amp