Tools

Online tool · Electrical

Cable sizing to AS/NZS 3008.1.1:2025

Enter one circuit — the load, the length, the voltage and how the cable is installed — and get the smallest conductor that carries the current and keeps the voltage drop within the limit.

Standard: AS/NZS 3008.1.1:2025 Full PDF calculation report: A$1.99 incl. GST

Who it is for
Electricians, electrical designers and engineers in Australia and New Zealand sizing one circuit of multicore copper or aluminium cable.
Not covered yet
Grouped circuits, single-core cables, parallel runs and DC. When your inputs need one of these, the tool says so instead of guessing.

Your circuit

Single-phase: a two-core cable. Three-phase: three- or four-core, balanced load.

Design current IB, up to 600 A.

One way, up to 2,000 m.

Line-to-line for three-phase, line-to-neutral for single-phase. 100–1,000 V.

Spaced = perforated tray, ladder or cleats. Enclosed = in conduit, duct or trunking. Not applied: the factor for an unperforated tray or a ceiling, and the depth and soil corrections in the ground (rated at 0.5 m in standard soil) — so a buried run never shows a full pass.

Aluminium starts at 16 mm².

PVC: thermoplastic V-75 / V-90. XLPE: the X-90 family.

Single-core is not covered yet.

This one plus any run alongside it. More than 1 needs grouping factors — not covered yet.

More options Protective device, voltage-drop method, ambient temperature, voltage-drop limit

0 = none: coordination is not checked. Enter a rating to check IB ≤ IN ≤ IZ. Up to 1,000 A.

A breaker to AS/NZS 60898.1 up to 125 A trips at I2 = 1.45 × IN. For a fuse or a larger breaker, enter I2.

0 = not known. An entered value always wins. Up to 1,450 A.

Worst case takes the load power factor equal to the cable’s. Load power factor applies Clause 4.5.

0.5 to 1. Leading power factor is out of scope.

Rated at 40 °C; other values apply the Table 3.44 factor, rounded up. 15–85 °C.

Rated at 25 °C; other values apply the Table 3.45 factor, rounded up. 10–40 °C.

Of nominal voltage. 5 % is the total from supply to any point (Clause 4.1.1(a)); a sub-circuit gets part of it. Up to 10 %.

Off: resistance at the insulation’s maximum temperature — conservative. On: estimated from the load, which lowers the drop.

More than 1 is not covered yet.

The answer

Enter the circuit and press Calculate. The answer appears here.

Disclaimer. Calculation aid to AS/NZS 3008.1.1:2025 for a competent person. It does not replace the designer’s responsibility under AS/NZS 3000. The checks this calculator did not run are listed under “Checks not run”.