Understanding Voltage Drop in Industrial Cables

Voltage drop is the loss along a conductor due to its resistance. For single-phase: Vd = 2 × L × I × ρ ÷ A, where ρ for copper is 0.0175 Ω·mm²/m.

Codes limit total drop to ~3% for lighting and 5% for power feeders (IEC 60364). If you exceed it, equipment under-volts, motors heat up, and contactors chatter. The fix is either a larger conductor cross-section or a shorter run.