In a section of 4" x 4" wireway, what is the maximum number of 8 AWG THHN/THWN conductors that can be installed?

To determine the maximum number of 8 AWG THHN/THWN conductors that can be installed in a 4" x 4" wireway, it’s important to understand the fill capacity as dictated by the National Electrical Code (NEC). The NEC provides guidelines to ensure that conductors are properly sized within raceways to avoid overheating and electrical hazards.

The wireway in question, measuring 4" x 4", has a certain fill capacity based on its dimensions. Specifically, for 8 AWG THHN/THWN conductors, the allowable fill is determined taking into account both the physical size of the conductors and the overall size of the wireway.

For conductors sized 8 AWG, the NEC suggests that in a common installation scenario, each conductor occupies a specific cubic inch space. Upon calculating the total available space inside the 4" x 4" wireway and dividing this by the cubic inch fill of a single 8 AWG conductor, you arrive at the maximum permissible quantity that can be safely installed without exceeding the fill limits.

By applying these calculations in compliance with NEC regulations, the maximum number of 8 AWG conductors that can be accommodated in a 4" x 4