🔌 Wire / Conduit Sizing Calculator
NEC ampacity table with derating factors — copper and aluminum conductors
Results
Design Load (with factors)
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A required ampacity
Derating Factor Applied
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combined factor
| AWG / kcmil | Ampacity (derated) | Status |
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NEC Reference (Table 310.15(B)(16))
Design ampacity = Load current × Continuous factor / (Temp correction × Conduit fill factor)
Always size breaker and wire together. Wire must have ampacity ≥ breaker rating × 1.25 for continuous loads.
Aluminum wire requires 1–2 sizes larger than copper for same ampacity. Minimum aluminum conductor: #6 AWG per NEC 310.106(B).