What does “derating” involve in conduit installations?

Derating in conduit installations refers to the practice of reducing the ampacity, or current-carrying capacity, of electrical wires to ensure safe operation under specific conditions. This reduction is necessary due to factors such as high ambient temperatures, the number of conductors bundled together, or when insulation types are limited. When conductors are installed in a conduit and subjected to these conditions, the heat generated by the electrical current can exceed safe levels, potentially leading to insulation degradation, short circuits, or fires.

To avoid such hazards, derating adjusts the allowable ampacity of the wires downward, ensuring that they operate well within safe temperature limits. This is particularly crucial in environments where multiple conductors share a conduit space or where external temperature affects the internal thermal conditions of the conduit. Thus, implementing derating helps maintain electrical safety and reliability in installations.