What is the ampacity of six 4 AWG THW copper conductors installed in a raceway at 30°C?

To determine the ampacity of six 4 AWG THW copper conductors installed in a raceway at a temperature of 30°C, it’s essential to refer to the National Electrical Code (NEC) tables, specifically Table 310.16, which outlines the ampacities of conductors based on their insulation types, sizes, and installation conditions.

For 4 AWG THW copper conductors, the base ampacity at 30°C is typically around 85 amperes for one conductor. However, when multiple conductors are installed together in a raceway, the NEC requires adjustments due to the potential heating effects from the grouping of conductors.

When determining the ampacity for multiple conductors, the NEC specifies that if more than three conductors are installed in a raceway, the ampacity must be derated. For six conductors, a common derating factor of 0.80 is typically applied.

So, the calculation would be as follows:

1. Determine the base ampacity for a single 4 AWG THW copper conductor, which is 85 A.

2. Apply the derating factor of 0.80 due to the six conductors:

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85 A \