How many 1 AWG THHN conductors can be added to a 4" x 4" metal wireway that contains 12 8 AWG THW conductors without exceeding allowable wire fill?

To determine how many 1 AWG THHN conductors can be added to the existing 4" x 4" metal wireway with 12 8 AWG THW conductors, one should refer to the National Electrical Code (NEC) guidelines regarding conductor fill in raceways.

First, it’s essential to ascertain the fill capacity of the wireway based on its size. A 4" x 4" wireway typically has a volume that permits a certain number of conductors, depending on their size. Each conductor size has a designated fill capacity measured in cubic inches.

Next, identify the existing fill from the 12 8 AWG THW conductors. Each 8 AWG THW conductor occupies a specific volume in the wireway. Once the total volume occupied by the 12 conductors is calculated, the remaining capacity of the wireway can be determined.

Subsequently, the volume that each 1 AWG THHN conductor occupies is calculated. With the remaining volume of the wireway known, dividing this by the volume taken up by one 1 AWG THHN conductor reveals how many of these conductors can fit without exceeding the wire fill limit.

Upon performing these calculations, the total number