Electrical Calculators

Cable Voltage Drop Calculator

Calculate cable voltage drop for single-phase or three-phase copper conductors.

Inputs

Cable length (one way)mCurrentAConductor areamm²Phase factor (2=1φ, √3≈1.732=3φ)

Result

Voltage drop

8.75V

Formula

Vd = (2 × L × I × ρ) / A (single-phase) — ρ_copper ≈ 0.0175 Ω·mm²/m

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Formula

Vd = (2 × L × I × ρ) / A    (single-phase) — ρ_copper ≈ 0.0175 Ω·mm²/m

(2 × 50 × 30 × 0.0175) / 6 = 8.75 V

+Acceptable voltage drop?

Typically ≤ 3% for lighting, ≤ 5% for power feeders.