Electrical systems • Cable comparison

Cable Voltage Drop Comparison Calculator

Compare two or three conductor options for steady-state AC voltage change. Enter guide assumptions or manufacturer R/X data; the tool does not select a cable.

Calculation scopeSingle-phase 2-wire or balanced three-phase only. No ampacity, breaker, fault, derating, starting-current, compliance or cable-suitability assessment.
Step 1

Circuit and cable data

Circuit type
V
A

Enter 0 to 1 inclusive.

Reactive direction

Cable options

Comparison order is not a recommendation or ranking.

Guide estimate assumptionsR = 23.7 ÷ S Ω/km for copper or 37.6 ÷ S Ω/km for aluminium; X = 0.08 Ω/km. S is CSA in mm². Use manufacturer mode when applicable cable data is available.
Option 1
mm²
Option 2
mm²
Step 2

Comparison result

Compare signed voltage change

Use the example values or enter your circuit and cable data.

Formula and sign convention

Z term = R × PF + X × sin φ. Lagging sin φ is positive; leading sin φ is negative. Single-phase 2-wire: ΔU = 2 × I × Z term × L. Balanced three-phase: ΔU = √3 × I × Z term × L. Percentage = ΔU ÷ system voltage × 100; receiving voltage = system voltage − ΔU.

Guide estimate assumptions

Guide mode uses R = 23.7/S Ω/km for copper or R = 37.6/S Ω/km for aluminium and X = 0.08 Ω/km, where S is CSA in mm². These are simplified planning inputs, not cable-specific manufacturer data.

Limits

Steady-state AC only. This calculator does not model conductor operating temperature, harmonics, parallel conductors, unbalanced systems, neutral current, cable construction, joints, source impedance, ampacity, derating, protective devices, short circuit, starting current or local-code compliance. A comparison result is not a safe, suitable, recommended or compliant cable selection.

Sources