Calculate the correct wire gauge per NEC 2023 Table 310.16. Handles temperature correction, conduit fill adjustment, and terminal temperature limits.
Based on NEC 2023 Table 310.16, 310.15(B)-(C), 110.14(C)
Click a preset to auto-fill, or enter custom values below
Applies 125% factor (NEC 210.19)
Correct wire sizing requires satisfying three independent constraints. The largest size required by any of these rules must be installed.
Most equipment terminals are rated for 75°C. You cannot use the 90°C rating of wire as its final capacity if the terminal can only handle 75°C.
High ambient temperatures or many wires in a conduit generate heat. We must derate the wire's 90°C base capacity to find its adjusted safe limit.
Loads running for 3+ hours (AC, Lighting, EV Chargers) require the conductor to be sized at 125% of the actual current.
Common wire sizes for 75°C copper conductors. Use the calculator above for precise NEC-compliant sizing with all derating factors applied.
*NEC 240.4(D) limits #14/#12/#10 to 15A/20A/30A overcurrent protection.
⚠️ IMPORTANT LEGAL DISCLAIMER
For Reference Only: This calculator is provided for educational and informational purposes only. It is not intended to be a substitute for professional engineering design, advice, or certification.
Code Compliance: Calculations are based on the 2023 National Electrical Code (NEC®). However, local codes, amendments, and Authority Having Jurisdiction (AHJ) requirements vary by location and may supersede standard NEC requirements.
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