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.
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.
2017 Code Language:
314.16(B)(5) Equipment Grounding Conductor Fill. Where one or more equipment grounding conductors or equipment bonding jumpers enter a box, a single volume allowance in accordance with Table 314.16(B) shall be made based on the largest equipment grounding conductor or equipment bonding jumper present in the box. Where an additional set of equipment grounding conductors, as permitted by 250.146(D), is present in the box, an additional volume allowance shall be made based on the largest equipment grounding conductor in the additional set.
2020 Code Language:
314.16(B)(5) Equipment Grounding Conductor Fill. Where up to four equipment grounding conductors or equipment bonding jumpers enter a box, a single volume allowance in accordance with Table 314.16(B) shall be made based on the largest equipment grounding conductor or equipment bonding jumper entering the box. A ¼ volume allowance shall be made for each additional equipment grounding conductor or equipment bonding jumper that enters the box, based on the largest equipment grounding conductor or equipment bonding conductor.
Based on the 2020 NEC, which of the following is true?
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