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Three-Phase Voltage Drop Calculator

Calculate three-phase voltage drop from current, conductor resistance, and one-way length (VD = √3 × I × R × L ÷ 1000).

Formula

VD = (√3 × I × R × L) ÷ 1000

VD
Voltage drop, in volts
I
Current, in amps
R
Conductor resistance, in ohms per 1000 ft
L
One-way circuit length, in feet

What this calculator does

Calculates voltage drop for a three-phase circuit, using the √3 line-to-line factor.

Use cases

  • Size a three-phase feeder run for acceptable voltage drop
  • Check a three-phase motor circuit's expected voltage drop at distance
  • Compare single-phase vs. three-phase voltage drop for the same load

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