AS/NZS 3000:2018 — commonly known as the Wiring Rules — is the foundational standard for electrical installations in Australia and New Zealand. Published jointly by Standards Australia and Standards New Zealand, it sets out the minimum requirements for the design, construction, inspection and testing of electrical installations. Every licensed electrician working in these markets needs a working understanding of the key clauses and how to apply them.
Structure of AS/NZS 3000
The Wiring Rules are organised into chapters that follow the lifecycle of an installation. Part 1 covers scope, definitions and general principles. Part 2 covers selection and erection of equipment. Part 3 covers inspection and testing. The standard works alongside companion documents: AS/NZS 3008.1 for cable selection (ampacity tables, voltage drop), AS/NZS 3017 for inspection and testing, and various product-specific standards.
In practice, the Wiring Rules do not stand alone. State and territory regulators in Australia (and WorkSafe New Zealand) may impose additional requirements through their own electricity regulations. Always check the relevant state or territory technical regulator's requirements alongside AS/NZS 3000.
Cable selection under AS/NZS 3008.1
Cable sizing under AS/NZS follows the same three-step process used in BS 7671: establish the design current (Ib), find a cable whose tabulated current-carrying capacity (It) exceeds the design current after applying correction factors, and verify that voltage drop is within the 5% recommended limit.
AS/NZS 3008.1.1 (for Australian conditions) and 3008.1.2 (for New Zealand) provide separate tables because the two countries have different soil thermal resistivity values and climate profiles. In Australia, for example, the reference ambient soil temperature used for buried cables is 25 °C, whereas New Zealand uses different values in different regions.
Correction factors in AS/NZS 3008.1 include:
- Ambient temperature (Table 23)— for installations where the temperature differs from the reference value of 40 °C (air) or 25 °C (buried).
- Grouping (Table 22) — for cables installed close together, reducing their ability to shed heat.
- Soil thermal resistivity (Table 28) — for direct-buried cables, where soil type significantly affects heat dissipation.
Voltage and frequency
The Australian and New Zealand supply is 230 V single-phase (line to neutral) and 400 V three-phase (line to line), at 50 Hz — the same nominal voltages as the UK and Europe. This means the current calculations, power formulas and voltage drop limits are directly comparable to BS 7671, unlike North American installations which use 120/240 V at 60 Hz.
The maximum recommended voltage drop under AS/NZS 3000 is 5%of the nominal supply voltage between the point of supply and any point in the installation. This equates to 11.5 V on a single-phase 230 V circuit.
Earthing systems
Australia and New Zealand use the MEN (Multiple Earthed Neutral) system, which is broadly equivalent to the TN-C-S system described in IEC 60364 and referenced in BS 7671. The neutral and protective earth conductors are combined in the distributor's network and separated at the point of supply (the main switchboard). Downstream of the main earth connection, the protective earth (PE) conductor must run separately from the neutral.
The main earthing conductor must be sized to carry the prospective fault current without damage until the protective device operates. AS/NZS 3000 Clause 5.5 sets out the minimum sizes, which are generally consistent with the adiabatic approach used in BS 7671 Section 543.
RCD requirements
AS/NZS 3000:2018 significantly expanded mandatory residual current device (RCD) protection compared to earlier editions. The key requirements are:
- All socket outletsin domestic and residential installations must have 30 mA RCD protection (Clause 2.6.3.2).
- Lighting circuits in domestic installations require RCD protection (Clause 2.6.3.2).
- Socket outlets in commercial and industrial premises that are used or likely to be used for portable equipment outdoors or in wet areas require RCD protection (Clause 2.6.3.3).
- Construction wiring — all socket outlets on construction sites must have RCD protection (Clause 7.3.3).
The 30 mA threshold for personal protection matches the BS 7671 requirement. RCDs for fire protection (where required) use a higher threshold of 300 mA.
Circuit protection and overcurrent devices
AS/NZS 3000 Clause 2.5 sets out the requirements for overcurrent protection. Every live conductor must be protected against overload and short circuit. The protective device must be rated to carry the design current continuously, and its characteristics must ensure it disconnects the circuit before the conductor is damaged.
Standard circuit breaker ratings follow the IEC 60898 series — 6, 10, 16, 20, 25, 32, 40, 50, 63 A and above for domestic and light commercial applications. Type B (3–5× rated current trip threshold) is standard for resistive and lighting loads; type C (5–10×) for motor and transformer loads. This mirrors BS 7671 practice and differs significantly from the NEC, which uses different standard sizes and trip curves.
Switchboard labelling and documentation
AS/NZS 3000 Clause 2.10.3 requires every switchboard to have a circuit schedule identifying each circuit, its protective device rating, and the loads it supplies. This must be permanently affixed and legible. The requirement exists so that anyone working on the installation in future can identify circuits without having to trace them.
A certificate of compliance or certificate of electrical safety (the name varies by state) must be issued for every new installation or significant alteration. The format is mandated by the relevant state or territory technical regulator and must be retained by the electrical contractor.
Special locations
Part 6 of AS/NZS 3000 covers special installations: swimming pools and spas, construction and demolition sites, agricultural and horticultural premises, caravans and caravan parks, and extra-low voltage installations. Each has supplementary requirements that apply in addition to the general rules. Swimming pools, in particular, have strict equipotential bonding and zone requirements that are closely aligned with BS 7671 Section 702.
Key calculators for AS/NZS work
The calculators most used for AS/NZS installations are the voltage drop calculator (which supports AS/NZS alongside NEC and BS 7671), the cable sizing calculator for sizing cables to AS/NZS 3008.1, and the cable derating calculatorfor applying temperature and grouping factors. All three support the 230 V, 50 Hz supply standard used in Australia and New Zealand.