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Voltage Drop Calculator — ChiefEngineer.in

Calculate voltage drop across a cable for DC, single-phase or three-phase.

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Formula

ΔV = 2ρLI/A (DC, single-phase)
ΔV = √3·ρLI/A (three-phase)
%ΔV = ΔV/Vnominal × 100

Variables

  • ρ — resistivity (Ω·mm²/m)
  • L — one-way length (m)
  • I — current (A)
  • A — cross-section (mm²)

Worked Example

Input: Cu, 50 m, 20 A, 4 mm², 230 V, single-phase

Result: ΔV ≈ 8.75 V, 3.80%

Assumptions & Notes

Resistance-only model. AC voltage drop should account for conductor reactance, power factor, installation method and applicable electrical standards. This is an estimate, not a cable-sizing approval.

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