AS/NZS 3000 — Wiring Rules
AU / NZ — Standards Australia / Standards New Zealand
AS/NZS 3000:2018 (Amendment 3:2023), jointly published by Standards Australia and Standards New Zealand, is the wiring rules standard for all fixed electrical installations across Australia and New Zealand up to 1000 V AC. It works with AS/NZS 3008.1.1 (cable selection — copper) and AS/NZS 3008.1.2 (aluminium), and Clause 3.6 limits total voltage drop to 5 % between the point of supply and any point in the consumer's electrical installation.
Scope and adoption
AS/NZS 3000 is mandatorily applied through state regulators (e.g., Energy Safe Victoria in Australia, WorkSafe NZ in New Zealand) and is the basis for the licensed electrician's Certificate of Compliance. Part 1 sets scope and definitions, Part 2 lists Essential Safety Requirements (clauses 2.1–2.10) covering shock, thermal, and fire protection, Part 3 covers selection and installation (cables, switchgear, accessories, switchboards, earthing systems), Part 4 covers special electrical installations (bathrooms 6.2, swimming pools 6.3, hazardous areas via AS/NZS 60079, EV chargers 4.16, solar PV via AS/NZS 5033). Clauses 1.7.1–1.7.4 mandate periodic inspection and testing for installations such as caravan parks and medical locations.
Cable sizing via AS/NZS 3008.1.1
Conductors are specified in mm² to standard sizes 1, 1.5, 2.5, 4, 6, 10, 16, 25, 35, 50, 70, 95, 120, 150, 185, 240, 300, 400, 500, 630 mm². AS/NZS 3008.1.1 Tables 3–13 give current-carrying capacity by installation method: unenclosed (Method 1), enclosed in air (Method 3), buried direct (Method 5), buried in conduit (Method 6), and on a cable tray (Methods 11–14). Typical 75 °C V-90 PVC copper in conduit (Method 3, single-phase) at 40 °C ambient: 1.5 mm² → 15 A, 2.5 mm² → 21 A, 4 mm² → 28 A, 6 mm² → 36 A, 10 mm² → 50 A. Clause 4.6 of AS/NZS 3008.1.1 lists derating factors for ambient temperature, depth of burial, soil thermal resistivity, and grouping (4 circuits in a tray = 0.77, 9 circuits = 0.55).
Protection and maximum demand
AS/NZS 3000 Clause 2.5 governs overcurrent protection: I_B ≤ I_N ≤ I_Z and I_2 ≤ 1.45 · I_Z, matching the IEC coordination conditions. Clause 2.6 mandates RCD protection at 30 mA for all socket outlets up to 20 A and final subcircuits supplying lighting in residential installations (Amendment 3:2023 extends this to all final subcircuits ≤ 32 A in domestic premises). Clause 2.7 covers earthing — Australia uses a Multiple Earthed Neutral (MEN) system, equivalent to IEC TN-C-S. Maximum demand is calculated per Clause 2.2 and Table C1: single domestic phase × cooking equipment + 50 % of heater load + lighting + socket diversity, used to size the consumer's mains and the main switch.
Voltage drop and notable differences
Clause 3.6 sets total voltage drop ≤ 5 % from the point of supply to any point of utilisation — measured across the consumer's mains, submain, and final subcircuit combined. There is no separate lighting-vs-power split as in BS 7671. The Australian supply standard is 230 V single-phase / 400 V three-phase (AS 60038) at 50 Hz, with statutory tolerance +10 %/-6 %. AS/NZS 3008.1.1 publishes voltage-drop tables in mV/A/m per cable size and method; 10 mm² 75 °C single-phase shows about 4.5 mV/A/m. Distinct from NEC (split-phase 240/120 V, AWG, 3 % advisory drop), BS 7671 (3 %/5 % split, ring finals), and IEC 60364 (3 %/5 % split, multiple national variants), AS/NZS 3000 enforces a single 5 % cap and the MEN earthing scheme.
FAQ
What is the Multiple Earthed Neutral (MEN) system?
MEN is the Australian/New Zealand equivalent of IEC TN-C-S earthing: the supply neutral is bonded to earth at multiple points along the distribution network and again at the consumer's main switchboard via the MEN link in the main earth bar. AS/NZS 3000 Clause 5.5 mandates the MEN link and prohibits separate switching of neutral and live conductors. The arrangement provides a low-impedance fault path so circuit breakers and fuses can clear earth faults within the disconnection times of Clause 1.5.5.3 (0.4 s for final subcircuits ≤ 32 A).
Why is AS/NZS 3000's voltage drop limit 5 % rather than split 3 %/5 %?
Clause 3.6.2 applies a single 5 % cap from the point of supply to any point in the consumer's installation regardless of load type, simplifying calculation across mains + submains + final subcircuits. Designers can still apply tighter internal targets for lighting where lamp performance demands it, but the standard's compliance criterion is the single 5 % figure rather than the load-type split used in BS 7671 525.201.
When is 30 mA RCD protection required under AS/NZS 3000 Amendment 3:2023?
Clause 2.6.3.2.2 requires 30 mA RCDs on all socket-outlet final subcircuits rated up to 20 A, all lighting final subcircuits in residential installations, and (post-Amendment 3:2023) all final subcircuits in domestic premises up to 32 A. Special locations such as bathrooms, swimming pools (Clause 6.3), and medical areas (Clause 7.7) have additional RCD or isolated supply requirements.
How is maximum demand calculated?
AS/NZS 3000 Clause 2.2 and Table C1 give the diversity calculation: cooking appliances at 50 % of full rating after the first 4 kW, fixed water heaters at 100 %, fixed space heaters at 75 % of the largest plus 50 % of the rest, lighting at the connected load up to 1000 W with 75 % thereafter, socket outlets at 10 A per first 20 outlets plus 5 A for each additional. The resulting demand sizes the consumer's mains conductors and the main switch.
How does AS/NZS 3000 interact with AS/NZS 3008.1?
AS/NZS 3000 is the installation standard — it dictates clearance, protection, switchgear arrangement, earthing, and inspection. AS/NZS 3008.1.1 (copper) and 3008.1.2 (aluminium) are the cable-selection standards — they publish the current-carrying capacity tables, derating factors, and voltage-drop coefficients. Together, an installer uses 3000 for the system architecture and 3008.1 for sizing the actual conductors, with both referenced on the certificate of compliance.