700.4 Emergency system capacity
What changed in 700.4
Emergency system capacity is now based on an Article 220 load calculation or another approved method.
Point by point
- New 700.4(B) says to size emergency system capacity with an Article 220 calculation or another approved method.
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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
Emergency system capacity is now based on an Article 220 load calculation or another approved method.
2023 NEC®Revised
Emergency system capacity now has to cover rapid load changes and transients, and a new subsection sets the rules for running emergency sources in parallel.
Open the 2023 page →2026 NEC®Revised
Commissioning was clarified, digital records are allowed, and the temporary connection rule was clarified.
Open the 2026 page →More 2020 changes in Article 700
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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