ELECTRICAL TOPIC
Voltage drop and conductor data: choose the right method
A voltage-drop result is only as useful as its conductor data and route assumptions. Choose a method that matches the information you actually have.
Check the coefficient basis
10 mV/A/m × 10 A × 50 m ÷ 1000 = 5 V
This uses a one-way 50 m route and a coefficient supplied for the relevant circuit geometry. A second loop or phase multiplier would double-count what the coefficient already represents.
1. Select data that matches the circuit
Cable-specific resistance and reactance can represent a particular conductor and AC arrangement. An mV/A/m coefficient packages assumptions from its data source and cannot be transferred between circuit geometries without checking that source. Simplified resistivity is useful for screening but is not a substitute for cable-specific AC data.
2. Use one-way route length consistently
The calculator asks for the route from source to load. Some formulas already account for the return path or three-phase geometry. For equal parallel runs, current sharing changes the result once; do not divide both the total current and the per-run coefficient by the number of runs.
3. Review temperature and other constraints
Copper or aluminium resistance generally changes with conductor temperature, which is not necessarily ambient air temperature. A selected voltage-drop target is a project input, not a universal limit. Ampacity, installation method, fault performance and equipment starting behaviour still need their own checks.