⚡ Voltage Drop Calculator
Wire sizing and voltage drop for AC and DC circuits
Results
Voltage Drop
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V
% Voltage Drop
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% (NEC max: 3%)
Voltage at Load
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V
Power Lost in Wire
—
W
Formula Reference
DC / Single Phase: Vdrop = 2 × I × Rwire
Three Phase: Vdrop = √3 × I × Rwire
Rwire = ρ × L / A (ρ Cu = 1.68×10&sup8; Ω·m)
NEC recommends max 3% voltage drop for branch circuits, 5% total (feeder + branch).