Cable Size & Voltage Drop

Cable Sizing & Voltage Drop Calculator

How It Works & Cable Sizing Logic

This dual-function calculator automatically recommends the optimal standard cable size (based on current-carrying capacity & ≤ 3% voltage drop) or evaluates voltage drop for any manually selected cable cross-section as per IEC standard parameters.

Selection & Calculation Logic:

1. Auto-Sizing Mode: Selects the smallest standard cable size that satisfies both continuous current capacity (Ampacity) and limits voltage drop to ≤ 3%.
2. Manual Evaluation Mode: Select any cable size directly from the dropdown list to test alternative cross-sections and observe real-time voltage drop results.

Governing Formulas:

1-Phase Voltage Drop (V): VD = (2 × L × I × ρ) / A
3-Phase Voltage Drop (V): VD = (√3 × L × I × ρ) / A
  • VD: Voltage Drop in Volts
  • L: One-way Cable Length (Meters)
  • I: Full Load Current (Amperes)
  • ρ (Rho): Material Resistivity (Cu = 0.018, Al = 0.028 Ω·mm²/m)
  • A: Conductor Cross-Section Area (mm²)
Voltage Drop (%): (VD / Supply Voltage) × 100
*Standard IEC limit: ≤ 3% for lighting/power branch circuits, ≤ 5% for general feeders.