Voltage drop tables for common wire sizes at various run lengths. Long wire runs increase voltage drop — use these charts to verify your wire gauge is adequate for the distance, or use our wire size calculator for custom scenarios.
Every foot of wire adds resistance. For long runs, the cumulative voltage drop can exceed safe limits even if the wire's ampacity rating is sufficient. NEC recommends keeping voltage drop under 3% for branch circuits.
As a rule of thumb: doubling the distance doubles the voltage drop. To compensate, move up one or two wire sizes (e.g., from 12 AWG to 10 AWG).