Construction
Wire Size Calculator (NEC)
NEC ampacity tables plus voltage drop limit. Wrong wire size = nuisance trips at best, fire at worst.
Minimum AWG
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- Ampacity limit
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- Voltage drop %
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- Per NEC + 3% drop
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FAQ
Why 3% voltage drop limit? +
NEC recommends 3% max on branch circuits, 2% on feeders, 5% total. Beyond that, motors run hot and lights dim.
Aluminum vs copper? +
Aluminum needs to be 2 sizes larger for the same ampacity. Watch for AL-CU listed devices and antioxidant compound.