Cable Size Calculator
Select minimum cable size based on current carrying capacity and voltage drop — with derating for real installation conditions.
Cable Size Comparison
| Size (mm²) | Rated (A) | Derated (A) | VD % | Status |
|---|
Voltage Drop vs Cable Size
Formulas Used
Design Current
Three Phase: Ib = P × 1000 / (√3 × V × PF) Single Phase: Ib = P × 1000 / (V × PF)Required Cable Capacity
Iz = Ib × (1 + margin/100) / (K_temp × K_group)Voltage Drop
Three Phase: VD = √3 × Ib × L × R / 1000 Single Phase: VD = 2 × Ib × L × R / 1000Learn More:
Voltage Drop in Electrical Circuits — Causes, Formula & How to Reduce It
Skin Effect in AC Conductors
Construction and Properties of Underground Cables
Calculation Assumptions
• Resistance-based voltage drop model (reactance neglected for LV)
• Conductor temperature at rated operating temperature
• Balanced three-phase load assumed
• No harmonic derating applied
• Single cable per phase assumed
• Preliminary sizing — verify against IS 3961 / IEC 60364
• Standard sizes: 1.5, 2.5, 4, 6, 10, 16, 25, 35, 50, 70, 95, 120, 150, 185, 240, 300 mm²