Electrical Cable Size Australia ^new^ May 2026

To combat voltage drop, the cable size must be increased. While a 1.5 mm² cable might handle the current of a 5-amp light over 10 metres, that same cable over 100 metres would fail the voltage drop calculation. Thus, for rural properties or large commercial floors, voltage drop—not current—often dictates the final cable size.

The Science and Regulation of Electrical Cable Sizing in Australia electrical cable size australia

The most fundamental factor in selecting cable size (measured in square millimetres (mm²) of cross-sectional area) is the expected load current. As current flows through a conductor (typically copper or aluminium), resistance generates heat. If a cable is too small for the load—for example, using 1.0 mm² cable for a 20-amp power circuit—the conductor will overheat. This heat degrades the insulation (usually PVC or XLPE), potentially leading to a short circuit or fire. To combat voltage drop, the cable size must be increased