Code Change Summary: Revised code language. The 2020 NEC^® will now only allow up to four equipment grounding conductors in a box to be counted as a single volume allowance.

For years, the NEC^® has allowed an unlimited number of equipment grounding conductors in a box or enclosure to be counted only as one conductor when calculating box fill. Whether the box contained one equipment grounding conductor or a hundred and one, only a single volume allowance in accordance with Table 314.16(B) was made based on the largest equipment grounding conductor or equipment bonding jumper present in the box.

In the 2020 NEC^®, a single volume allowance can be used for up to four equipment grounding conductors entering the box and any more than that will each be assigned ¼ volume allowance based on the largest equipment grounding conductor or equipment bonding conductor entering the box.

For example, NEC^® Table 314.16(B) assigns a cubic inch volume of 2.00 for each 14 AWG conductor. In the image, there are six 14 AWG equipment grounding conductors entering the box.

• The first four equipment grounding conductors = 2.00 in.³
• The next two equipment grounding conductors = 1.00 in.³ (2.00 in.³ X ¼ = .5 in.³) (2 more wires X .5 in.³ = 1.00 in.³)
• Total equipment grounding conductor fill = 3. 00 in.³

This code change is meant to address the overcrowding that can occur in a box especially with some of the newer electronic type switching devices and GFCI/AFCI type devices that occupy a significant amount of room in the box.

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 2020 NEC^® edition of NFPA 70.