314.16 Box fill
What changed in 314.16
Box fill for EGCs changed: the first four EGCs in a box count as one volume, and each one past four adds a quarter volume.
Point by point
- The first four EGCs or bonding jumpers in a box together count as one volume allowance, sized by the largest one.
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Get the whole breakdown
- 2 more points on exactly what changed
- The 2017 rule next to the 2020 rule, side by side
- Why it changed
- What to do and check on the job
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This section across NEC® editions
2020 NEC®RevisedYou're here
Box fill for EGCs changed: the first four EGCs in a box count as one volume, and each one past four adds a quarter volume.
2023 NEC®Revised
Terminal blocks mounted inside a box now take up box fill volume, sized by the largest conductor landed on them.
Open the 2023 page →2026 NEC®Revised
Splicing connectors like wire nuts are now specifically addressed and don't count in box fill.
Open the 2026 page →More 2020 changes in Article 314
This is a plain-English summary, not the NEC®'s exact wording. Always check the full section in the NEC® edition your area has adopted, plus any local amendments.
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