450.9 Transformer ventilation
What changed in 450.9
Transformers with a flat top in a readily accessible spot must now carry a marking that prohibits storing things on them.
Point by point
- New marking: a transformer with a horizontal top that's readily accessible must be labeled to prohibit storage on it.
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Get the whole breakdown
- One more point 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
Transformers with a flat top in a readily accessible spot must now carry a marking that prohibits storing things on them.
2023 NEC®No change
This section did not change from 2020 to 2023.
2026 NEC®No change
This section did not change from 2023 to 2026.
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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