Voltage Drop Calculator

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Calculate voltage drop in a wire run from gauge, length, current and material. Check whether the drop stays within the recommended 3% for copper or aluminum, single or three phase.

A
m
V
Source Load
Voltage drop –
Voltage at load –
Within 3%? –
Resistance of run (per leg) –
Single-phase counts both conductors (2 × length); three-phase uses √3 × length. Resistivity assumes copper or aluminum at about 20 °C. The 3% guideline is a common branch-circuit recommendation.
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