Cable Sizing & Voltage Drop Calculator
VOLTAGE DROP · Cu / Al · 1φ / 3φHow it is calculated
Three-phase: V_drop = √3 × I × L × (ρ / S)Single-phase: V_drop = 2 × I × L × (ρ / S)
Where I is the load current in Amps, L is the cable length in meters, S is the cross-sectional area in mm², and ρ is the resistivity of the material (0.0178 Ω·mm²/m for Copper, 0.029 Ω·mm²/m for Aluminum at 20°C). Note: AC cable reactance is omitted for simplicity; for large cables (> 50 mm²), reactance may increase the voltage drop slightly.
FAQ
What is the maximum allowed voltage drop?
According to IEC 60364-5-52, the maximum recommended voltage drop between the origin of the installation and any load point is 3% for lighting circuits and 5% for other uses (motors, heating).
How does conductor material affect voltage drop?
Aluminum has higher electrical resistivity than Copper (approximately 60% higher). Therefore, an aluminum cable requires a larger cross-section than a copper cable to carry the same current with the same voltage drop.
Why does length increase voltage drop?
Cable resistance is directly proportional to its length. A longer run means higher resistance, leading to a larger voltage drop. To compensate for long runs, you must increase the cable cross-section.