TL;DR
Circuit derating is the reduction of a conductor's allowable current when installation conditions trap heat, such as bundling several cables, running conduit through a hot attic, or high ambient temperatures. The NEC provides adjustment factors that can force an installer to upsize wire, which is common on long EV-charger runs sharing a raceway.
What it means
Circuit derating is the reduction of a conductor's allowable current when installation conditions trap heat, such as bundling several cables, running conduit through a hot attic, or high ambient temperatures. The NEC provides adjustment factors that can force an installer to upsize wire, which is common on long EV-charger runs sharing a raceway. A bid that jumps from 6 AWG to 4 AWG copper for the same breaker size often reflects this calculation rather than padding.
Where it sits in the glossary
Circuit derating is part of the Trade jargon group inside the ProFix Directory glossary. Browse every term in this category from the glossary index.
Why Ohio homeowners should know it
This is a term Ohio homeowners encounter when reading contractor quotes, hiring paperwork, or inspection reports. Understanding it well enough to ask one good follow-up question is usually all the protection a homeowner needs.
ProFix Directory keeps definitions short on the index page and saves the longer context — Ohio-specific rules, where the term comes from, and which ProFix tools touch it — for these per-term pages so the term is easy to cite and easy to share.
ProFix tools that touch this term
See also
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