What is the total volume of a 3 in. × 2 in. × 2 in. device box for conductor fill?

To determine the total volume of the device box, the dimensions given are 3 inches by 2 inches by 2 inches. To calculate the volume, you multiply these three dimensions together:

Volume = Length × Width × Height

Volume = 3 in. × 2 in. × 2 in. = 12 cubic inches.

When calculating the allowable fill for a device box according to the National Electrical Code (NEC), however, not all of this volume may be counted towards the conductor fill. Typically, the NEC specifies certain rules for determining the effective volume of a box for conductors, taking into account factors such as the number of conductors, the size of the conductors, and any additional devices or fittings present.

In this question, it seems the student has arrived at an answer that interprets the total volume in a simplified manner without fully accounting for the conductor fill requirements outlined by the NEC. The correct interpretation, based on the proper application of NEC rules to a standard box volume calculation, would yield a result more reflective of the code’s guidelines on how to effectively measure usable volume for conductors.

Therefore, while calculating the physical volume of a box yields the basic multiplication result, applying NEC rules leads to certain prescribed values that