For three 10 AWG FEP copper conductors installed in a metal raceway at an ambient temperature of 60°C, what is the calculated ampacity?

To determine the calculated ampacity for three 10 AWG FEP copper conductors installed in a metal raceway at an ambient temperature of 60°C, it's important to refer to the National Electrical Code (NEC) guidelines which dictate how ampacity is adjusted based on temperature and the number of conductors.

The base ampacity for a 10 AWG copper conductor at a standard temperature of 30°C is typically listed at 30 amps. However, because the installation is in a metal raceway and the ambient temperature is elevated to 60°C, adjustments need to be made for both the temperature and the bundling of the conductors.

First, a temperature correction factor must be applied to account for the increase in ambient temperature. As the temperature rises, the ampacity rating of conductors decreases because the conductors may not dissipate heat effectively.

Next, since there are three conductors installed in the metal raceway, additional derating must be considered. According to NEC guidelines, when three or more conductors are installed in a raceway, the ampacity must be reduced to account for the fact that multiple conductors in close proximity can create a heat buildup.

Taking these factors into consideration, the calculated ampacity for three conduct