240.4 Protection of conductors
What changed in 240.4
Adjustable-trip breakers can use the next-size-up rule if access is restricted, 14 AWG copper-clad aluminum got a 10-amp limit, and dwelling services and feeders can be protected per 310.12.
Point by point
- The base rule stays: a conductor's overcurrent device can't be larger than its ampacity unless 240.4(A) through (H) allows it.
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- 4 more points on exactly what changed
- The 2020 rule next to the 2023 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®No change
This section did not change from 2017 to 2020.
2023 NEC®RevisedYou're here
Adjustable-trip breakers can use the next-size-up rule if access is restricted, 14 AWG copper-clad aluminum got a 10-amp limit, and dwelling services and feeders can be protected per 310.12.
2026 NEC®No change
This section did not change from 2023 to 2026.
More 2023 changes in Article 240
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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