The Advanced Wire Ampacity Calculator will calculate the maximum ampacity for a wire based on wire gauge, preferred (or available) wire insulation, conductor type and installation specifications. This calculator also provides wire size correction factors for temperature, number of conductors in a raceway, and voltage drop for long wire runs. This calculator is based on NEC (NFPA 70®: National Electrical Code® (NEC®), 2014 Edition) Table 310.15(B)(16-17).

Enter the information below to calculate the ampacity for the selected wire gauge and given conditions.

For simpler circuits that do not need temperature or number of conductors correction factors, use the Wire Size Calculator.

For long conductor runs where voltage drop may be an issue, use the Voltage Drop Calculator to determine voltage drop and the Circuit Distance Calculator to determine maximum circuit length. Visit the Tables page to view reference tables such as Maximum Ampacity for Current-Carrying Conductors.

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