Code Change Summary: New requirements added for 10 AWG and 12 AWG conductors entering the back of a box.

In the 2023 NEC^®, Section 314.24(B)(4) was expanded to require additional spacing between the back of a box and the device or equipment installed in the box. This new language is specific to installations where 10 AWG or 12 AWG conductors enter the center of the rear of the box to supply the device or equipment. Basically, the conductors enter right behind the device and there will be little room for wire management.

In the 2023 NEC^®, Section 314.24(B)(4) now has three rules that apply to box installations supplied by 10 or 12 AWG conductors:

1. Boxes that enclose devices or equipment supplied by 12 or 10 AWG conductors must have an internal depth at least 1-3⁄16 inch.
2. If equipment projects rearward from the mounting plane of the box by more than 1 inch, the box must have a depth no less than the equipment plus 1⁄4 inch.
3. If the wiring enters the center of the back of a box opposite the equipment, the minimum clearance must be increased to 1⁄2 inch.

The reason behind the code change was to make sure there is enough room right behind the device or utilization equipment to allow the conductors to be routed to their termination point without damage or pinching.

Below is a preview of the NEC^®. See the actual NEC^® text at NFPA.ORG for the complete code section. Once there, click on their link to free access to the 2023 NEC^® edition of NFPA 70.