0 V drop
—
% drop
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Voltage at load
Wiring regulations generally recommend keeping voltage drop under about 3–5%.
Frequently Asked Questions
How is voltage drop calculated?
For a single-phase circuit, Vdrop = 2 × ρ × L × I ÷ A, where ρ is the conductor resistivity (≈0.0175 Ω·mm²/m for copper), L is the one-way length, I the current and A the conductor cross-section. Three-phase uses √3 instead of 2.
Calculate the voltage drop in a cable run from current, length, conductor size and material.