310.15 Ampacity tables
What changed in 310.15
The rules on when a neutral counts as current-carrying were put into a clear list. The requirements themselves didn't change.
Point by point
- 310.15(E), the neutral conductor rule, was reorganized into a list.
The full lesson is in the Pro Version
Get the whole breakdown
- 2 more points on exactly what changed
- The 2023 rule next to the 2026 rule, side by side
- Why it changed
- What to do and check on the job
One membership unlocks every NEC® change lesson for 2020, 2023 and 2026, plus every video, quiz, flashcard and the Testing Center.
Checking your membership…
This section across NEC® editions
2020 NEC®Revised
The ampacity tables went back to their old numbers, Table 310.16 through 310.21. Sizes not in the tables can now be interpolated under engineering supervision, and new notes point to conductor properties and cords.
Open the 2020 page →2023 NEC®Revised
The rooftop distance that triggers the 60°F temperature adder dropped from 7/8 inch to 3/4 inch.
Open the 2023 page →2026 NEC®RevisedYou're here
The rules on when a neutral counts as current-carrying were put into a clear list. The requirements themselves didn't change.
More 2026 changes in Article 310
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.
NEC® and National Electrical Code® are registered trademarks of the National Fire Protection Association (NFPA). Electrical Exam Coach is not affiliated with or endorsed by NFPA.
Find it faster on test day