Cable Size in Melbourne (2026)

What a cable size costs in Melbourne

A cable size calculator in Melbourne works out the right cable gauge, in square millimetres, for a circuit from the load in amps, the run length that causes voltage drop, and the derating for the install conditions. The principle is safety and efficiency: undersizing overheats the cable and is a fire risk, while oversizing wastes copper, so the calculator finds the smallest safe gauge that carries the load within the voltage-drop limit. It is a planning guide, because the work itself is licensed.

Run length drives the sizing on a long Melbourne circuit, such as a feed to a studio, a shed or a heat pump at the end of a long inner-suburban block, where voltage drop forces a larger gauge. Melbourne's cold winter adds a load factor rather than a cable one, because electric heating and heat pumps draw heavily through winter, so a circuit sized for a big winter heating load needs the capacity the calculator sets. A cable bundled in a wall cavity or a period home's confined subfloor derates and must be sized for the install.

This is licensed work, because in Victoria it is illegal and dangerous for anyone but a licensed electrician to install or alter fixed wiring, so the calculator helps you understand the gauge, not do the job. The electrician sizes and installs the cable to the wiring rules under the Victorian Building Authority, which licenses electrical work. For a Melbourne job, the clearest use of a cable size calculator is to enter the load, the run length and the install conditions, so you understand the gauge the electrician will use.