What is the ampacity of one of twenty-four 12 AWG THWN copper motor circuit conductors?

To determine the ampacity of one of twenty-four 12 AWG THWN copper motor circuit conductors, it's important to understand how ampacity is defined and the relevant standards that govern it.

Ampacity refers to the maximum amount of electrical current a conductor or circuit can carry before sustaining immediate or progressive deterioration. The National Electrical Code (NEC) sets forth guidelines for determining the ampacity of different conductors based on various factors, including conductor material, insulation type, and installation conditions.

For 12 AWG copper wire, under standard conditions and for non-continuous loads, the typical ampacity listed in NEC tables is around 20 A. However, considering the nature of motor circuits and grouping conductors, adjustments need to be made. The derating factors apply, especially when multiple conductors are used in parallel, such as in this scenario with twenty-four conductors.

When multiple conductors are bundled together, the NEC recommends applying derating factors to prevent overheating. Based on NEC guidelines, the circuit's capacity might be reduced slightly due to these conditions. However, the ampacity for a single 12 AWG THWN copper conductor generally still supports a load of approximately 25 A, according to its standard ratings for individual,