What is the smallest size junction box for the specified installation with multiple conductors?

When determining the appropriate size for a junction box with multiple conductors, it is essential to consider the volume allowances specified in the National Electrical Code (NEC) or other applicable regulations. The NEC provides guidelines on the minimum box size necessary based on the number of conductors.

The answer indicates that the 10" x 10" x 4" deep box is the smallest suitable size for the installation. This size meets the volumetric requirements set out in the code for accommodating the number and size of conductors involved while providing adequate space for any splices or connections that may need to be made within the box. A box that is too small could lead to overheating and present hazards due to crowding of the conductors, which is why adhering to the volume calculations is crucial.

The other choices represent larger boxes, which, while adequate for the installation, do not meet the criteria for being the smallest sufficient option. Choosing the smallest acceptable size ensures both compliance with code requirements and efficient use of materials. In summary, the 10" x 10" x 4" deep box is the correct answer as it is aligned with the necessary volume requirements for the multiple conductors involved in the installation, making it the optimal choice for this scenario