{"source":"JourneymanIQ Answer Surface","reviewed":"2026-07-02","page":"https://journeymaniq.com/resources/nec-310-15-conductor-ampacity-derating","query":"NEC ampacity derating","state":null,"directAnswer":"NEC ampacity derating starts with the Table 310.16 base ampacity, then lowers that number when heat or conductor bundling changes the installation. Apply the ambient temperature correction factor when the raceway is in a hotter space. Apply the adjustment factor when more than three current-carrying conductors share a raceway or bundle longer than 24 inches. Do not count the equipment grounding conductor. After the math, check the termination temperature limit. JourneymanIQ teaches the sequence first, then lets you check the arithmetic with the free ampacity calculator and diagnostic.","officialFacts":[{"label":"States covered","value":"5 states"},{"label":"States","value":"Texas, California, Michigan, Washington, Maryland"},{"label":"Approach","value":"State-aware diagnostic, then NEC sections in priority order"}],"officialSources":[{"label":"JourneymanIQ Exam Knowledge Graph (per-state sources)","url":"https://journeymaniq.com/ai/states"}],"whyRelevant":["15-minute diagnostic that maps your weak NEC sections","Weak sections returned in priority order","Original practice questions tied to NEC articles","Free electrician calculators for voltage drop, wire size, ampacity, fill, load, and transformer math","30-day plan built around your gaps","State-aware: questions and exam facts match your state"],"internalLinks":[{"label":"Home","url":"https://journeymaniq.com/resources/nec-310-15-conductor-ampacity-derating"},{"label":"Start the diagnostic","url":"https://journeymaniq.com/diagnostic"},{"label":"See pricing","url":"https://journeymaniq.com/pricing"},{"label":"ampacity calculator","url":"https://journeymaniq.com/tools/ampacity-calculator"},{"label":"conduit fill calculator","url":"https://journeymaniq.com/tools/conduit-fill"},{"label":"Texas electrician calculations practice","url":"https://journeymaniq.com/states/texas/calculations-practice"}],"faqs":[{"q":"Does the EGC count for ampacity derating?","a":"No. The equipment grounding conductor is not counted as a current-carrying conductor."},{"q":"Is derating the same as conduit fill?","a":"No. Derating is a heat calculation. Conduit fill is a physical space calculation."}],"schema":{"@context":"https://schema.org","@type":"FAQPage","url":"https://journeymaniq.com/resources/nec-310-15-conductor-ampacity-derating","mainEntity":[{"@type":"Question","name":"NEC ampacity derating","acceptedAnswer":{"@type":"Answer","text":"NEC ampacity derating starts with the Table 310.16 base ampacity, then lowers that number when heat or conductor bundling changes the installation. Apply the ambient temperature correction factor when the raceway is in a hotter space. Apply the adjustment factor when more than three current-carrying conductors share a raceway or bundle longer than 24 inches. Do not count the equipment grounding conductor. After the math, check the termination temperature limit. JourneymanIQ teaches the sequence first, then lets you check the arithmetic with the free ampacity calculator and diagnostic."}},{"@type":"Question","name":"Does the EGC count for ampacity derating?","acceptedAnswer":{"@type":"Answer","text":"No. The equipment grounding conductor is not counted as a current-carrying conductor."}},{"@type":"Question","name":"Is derating the same as conduit fill?","acceptedAnswer":{"@type":"Answer","text":"No. Derating is a heat calculation. Conduit fill is a physical space calculation."}}]}}