AS/NZS Voltage Drop
A worked scenario showing how AS/NZS voltage drop calculations play out on a real commercial run.
Here's a concrete voltage drop scenario worked through under AS/NZS 3008.1.1's method, on a commercial cable run.
| Parameter | Value |
|---|---|
| Load | 50A, three-phase |
| Run length | 40 meters, one-way |
| Cable under test | 16mm² copper |
AS/NZS 3008.1.1 provides resistance and reactance data specific to each conductor size and configuration, used to calculate the actual voltage drop for the given current and length. On a 40-meter three-phase run at 50A, the result needs to be checked against the applicable percentage limit for the circuit type — general power circuits typically have more headroom than circuits with a tighter operational requirement.
Voltage drop scales directly with both current and length — doubling either roughly doubles the drop. This is why long commercial runs to a remote plant room or distant load center deserve a dedicated voltage drop check rather than an assumption that "the cable's rated ampacity is high enough, so it's fine."
Run your own length and load through the AS/NZS Voltage Drop calculator.
Engr. Jason Morales — Founder, SolarEnergyPH & OhmWorks