AS/NZS Wiring Rules Reference

Electrical installation in Australia and New Zealand is governed by a pair of joint standards. AS/NZS 3000 - the Wiring Rules - is the headline installation standard, equivalent in role to BS 7671 in the UK or the NEC in the US. AS/NZS 3008.1 (with separate parts for Australia and New Zealand conditions) is the dedicated electrical cable selection standard, providing the current ratings and voltage-drop data used to size conductors. The Voltix calculators for this region follow both.

The two standards at a glance

AS/NZS 3000 - Wiring Rules

AS/NZS 3000 sets the safety requirements for the design, construction and verification of electrical installations: protection against shock and overcurrent, earthing arrangements, and the rules for selecting and installing wiring systems. It cross-references AS/NZS 3008.1 for the detailed cable-rating tables rather than embedding them, which keeps cable selection in one focused document.

AS/NZS 3008.1 - Cable selection

AS/NZS 3008.1 is where the numbers live. It provides current-carrying capacity tables against installation method, conductor material and insulation type, along with three-phase and single-phase voltage-drop figures (expressed in mV/A/m, in the same family as the BS 7671 method). It also defines the temperature and grouping derating factors that reduce the tabulated rating for real installation conditions.

Key differences from BS 7671

The methodology will feel familiar to anyone who works with BS 7671, but there are important differences:

• Voltage: the nominal supply is 230 V single phase and 400 Vthree phase at 50 Hz, matching the UK. The recommended overall voltage drop is 5% from the point of supply to any point in the installation.
• Cable tables in a separate standard: ratings come from AS/NZS 3008.1 rather than an appendix to the wiring rules, and the installation method definitions differ in detail from the BS 7671 reference methods.
• Earthing: the predominant system is MEN (Multiple Earthed Neutral), in which the neutral and earth are connected at the main switchboard. This is the local equivalent of the TN-C-S arrangement and affects how the protective earthing conductor and main earthing conductor are sized.
• Terminology:expect “active” for line conductor, “protective earth” for the earthing conductor, and “switchboard” for the distribution board.