AS/NZS 3000:2018 — the Wiring Rules — is 600+ pages of regulation that decide whether you walk out of the licence exam with a ticket or a re-sit booking. This guide is the working sparkie's cheat sheet: the clauses, tables and concepts that turn up on the exam most often, with worked examples and the fastest way to commit them to memory.
Related: Brush up on the voltage systems behind the clauses with our guide to 120V vs 208V vs 240V vs 277V vs 480V electrical voltages explained.
The structure of the standard
AS/NZS 3000 splits into 8 parts. The exam loves Parts 1, 2 and 5 most:
- Part 1 — Scope, application, fundamental safety requirements (touch voltages, MEN system fundamentals).
- Part 2 — Installation requirements (protection, isolation, switching, RCDs, voltage drop).
- Part 3 — Selection and installation of wiring systems (cable routes, conduit fill, support).
- Part 4 — Selection and installation of appliances and accessories.
- Part 5 — Earthing arrangements (MEN, main earthing conductor sizing, bonding).
- Part 6 — Damp situations (bathrooms, swimming pools, saunas).
- Part 7 — Special installations (medical, hazardous, generating systems, solar PV).
- Part 8 — Verification (inspection sequence, testing methods).
The clauses you must know cold
Clause 1.5 — touch voltage
50 V AC / 120 V DC ripple-free is the conventional touch-voltage limit before automatic disconnection is required. This is the foundation of every protection question on the exam.
Clause 2.5 — protection against overcurrent
Every circuit must be protected against overload (In ≥ Ib, In ≤ Iz) and short-circuit. Worked example: a 16 mm² thermoplastic cable in conduit on insulated wall has Iz ≈ 80 A. Pick the next standard MCB rating below 80 A that's above your design current — typically 63 A.
Clause 2.6 — RCD protection
30 mA RCDs are mandatory on:
- All socket-outlets ≤ 32 A in domestic premises
- All final sub-circuits supplying lighting in domestic premises
- Socket-outlets in non-domestic premises ≤ 20 A in general use areas
Trip time: 40 ms at 5×IΔn, 300 ms at 1×IΔn for Type I/AC devices.
Clause 3.6 — voltage drop
Maximum 5% from point of supply to point of utilisation. Split is your choice but typically 1.5% on consumer mains, 0.5% on submains, 3% on final sub-circuits.
Clause 5.3 — main earthing conductor
Memorise Table 5.1. The pattern: up to 16 mm² active = same size earth; 25 mm² active = 6 mm² earth; 35 mm² active = 10 mm² earth; 50 mm² active = 16 mm² earth. Beyond 50 mm², half the active CSA.
The calculations to drill
Cable size by current
Three-step: (1) calculate Ib from the load, (2) apply derating factors (ambient, grouping, insulation), (3) pick a cable from AS/NZS 3008 Table 4–13 whose Iz ≥ derated Ib. Worked example: 32 A continuous load, 40 °C ambient (factor 0.94), grouped with 2 others (factor 0.80). Derated Ib = 32 / (0.94 × 0.80) = 42.6 A. Smallest cable with Iz ≥ 42.6 A in your installation method is your answer.
Voltage drop
Vd = Ib × L × mV/A/m / 1000. Worked: 32 A over 40 m on 6 mm² (7.3 mV/A/m) = 32 × 40 × 7.3 / 1000 = 9.34 V. 9.34 / 230 = 4.0%. Pass for final circuit.
Fault loop impedance
Zs ≤ Uo / Ia, where Ia is the current causing disconnection in the required time. For a 32 A Type C MCB needing 0.4 s disconnection, Ia = 10 × 32 = 320 A. Zs ≤ 230 / 320 = 0.72 Ω.
The "always asked" topics
- MEN system — purpose, how it works, why the neutral and earth are bonded only at the switchboard.
- Disconnection times (Table 1.5) — 0.4 s for final ≤ 32 A on TN, 5 s for distribution.
- Bathroom zones (Clause 6.2) — zone 0, 1, 2 and what's allowed in each.
- Solar PV (Section 7.4) — DC isolators, AC isolators, labelling.
- Verification (Part 8) — sequence: continuity, IR, polarity, Zs, RCD operation.
How to actually remember any of this
You don't memorise standards by reading them. You memorise them by being asked questions and getting them wrong, repeatedly, until you stop getting them wrong. That's why Voltly drills you on the same regulation in 10 different framings — by the 10th, it's instinct. Read the clause once. Drill it 100 times. The exam will feel familiar.