Wire Gauge Ampacity Calculator
Determine the minimum safe AWG wire size for your electrical circuit using NEC ampacity tables, voltage drop formulas, and derating factors.
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Common Use Cases
Used by electricians, electrical engineers, solar installers, and DIY homeowners to determine the minimum safe wire gauge for branch circuits and feeder runs. Ensures NEC code compliance with voltage drop and derating considerations.
How It Works
Uses NEC Table 310.15(B)(16) ampacity data with temperature and bundling derating factors. Single-phase: Vd = (2 × L × I × R) / 1000. Three-phase: Vd = (√3 × L × I × R) / 1000. Selects the smallest gauge where corrected ampacity ≥ load current, then validates voltage drop against the user's maximum.
Fun Fact: The National Electrical Code (NEC) has been in use since 1897 and is updated every three years. NEC Table 310.15(B)(16) is one of the most referenced tables in the entire codebook for sizing branch circuit conductors.
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