Electrical Rough-In Inspection Requirements for Residential Builds (AU)

What it is

Electrical rough-in is the stage where cabling, switch and outlet boxes, light points and the switchboard backplate are installed inside the framing before plasterboard goes on. It is the moment when everything that will sit hidden inside walls and ceilings can still be seen, touched and rerouted without breaking a finished surface.

The rules are set by AS/NZS 3000 (the Wiring Rules) which the National Construction Code calls up through state electrical safety Acts. The work must be done by a licensed electrician. In Victoria a Licensed Electrical Inspector (LEI) must physically inspect prescribed work at rough-in. Other states rely on the licensed electrician issuing a Certificate of Electrical Safety or Certificate of Compliance for Electrical Work after testing.

What the inspector actually checks

Cable routing and protection

Cables are checked for the correct route, depth in studs and protection against mechanical damage. AS/NZS 3000 requires cables in walls to either run in a safe zone (the 150 mm bands around a switch or outlet, and the 150 mm bands at the top and bottom of a wall) or sit at a depth of at least 50 mm from the face of the stud. Where cables sit closer than 50 mm a steel nail plate is needed.

Cables through metal studs need grommets to stop the sharp edge cutting the sheath. Cables through fire-rated walls need approved fire-rated sealant around the penetration.

Cable supports and clipping

Twin and earth (TPS) cable needs support at maximum 600 mm spacing in vertical runs and along the underside of joists. Loose cable draped through ceiling spaces is one of the most cited rough-in defects. The inspector lifts insulation in a few sample bays to check support is real and not just at the visible ends.

Switchboard backplate and cutouts

The switchboard location is checked against the plans, with attention to height (the top device handle should be no higher than 1.85 m for accessibility), front clearance, and the cutouts for the main switch, RCD/MCBs and any solar or battery isolators. Penetrations into the meter box from the consumer mains must be sized for the cable and rated for ingress protection where outside.

Earthing and bonding

The main earth bar location and earth stake or structural earth connection is inspected. Equipotential bonding to metal water and gas pipework is checked at the rough-in stage because it is much easier to confirm before walls are sheeted. Steel-framed houses need supplementary bonding to the frame per AS/NZS 3000 Clause 5.6.

Cable sizing and circuit count

The inspector cross-checks cable size against the proposed circuit load. Lighting circuits typically use 1.5 mm two and a half core TPS. General power circuits use 2.5 mm. Cooktops, ovens and hot water units use larger cables matched to their nameplate current. Each final subcircuit must originate from an RCD at the switchboard.

Light points, fans and ceiling penetrations

Cable tails at light points are checked for length, insulation condition and box type. Bathroom fan and heat lamp wiring is checked against the IP zoning rules in AS/NZS 3000 Section 7. Recessed downlight cable approaches need to keep clear of insulation unless the fitting is rated for direct contact.

RCD coverage

Under AS/NZS 3000 Amendment 2 (2021) every final subcircuit in a domestic installation must be protected by a 30 mA RCD. This applies to lighting, power, fixed appliances such as ovens and hot water units, and air conditioning circuits. The rough-in is when the inspector confirms there are enough RCD ways at the board to cover the planned circuits.

The pre-plaster compliance step

In Victoria the LEI inspects the prescribed rough-in work and issues a Certificate of Electrical Safety (CES) only after the work is tested at final fix. The rough-in inspection itself is recorded against the prescribed work notice.

In NSW, Queensland, South Australia, Western Australia, Tasmania, ACT and NT the licensed electrician self-certifies through a Certificate of Compliance for Electrical Work (or state equivalent). A pre-plaster check by the electrician is industry best practice even where the regulator does not mandate an external inspector. Builders often book the electrician for a pre-plaster walk-through with the site supervisor to sign off before lining trades arrive.

Common reasons rough-in fails

• Cables routed outside safe zones at less than 50 mm depth with no nail plate
• Missing earth bond to metal water pipework
• RCD count at the board too low for the planned circuit list
• Light point boxes set proud of the stud face so the fitting will not sit flush
• Bathroom wiring crossing IP zones around the bath or shower
• Cables piled in the ceiling space with no clipping
• Smoke alarm interconnect cable run as a single core where two core plus earth is required

What to give the inspector

The electrician should have the approved electrical plan, the switchboard schedule, the manufacturer data for any non-standard fittings, and the test instruments needed for any interim continuity check. Photographs of cable routes taken before sheeting protect everyone if a fault is found later.

Related rules

AS/NZS 3000 (Wiring Rules) is the primary technical reference. AS/NZS 3008.1.1 covers cable selection. State electrical safety Acts give the standard legal force and prescribe the form of the compliance certificate. The NCC Volume Two calls up smoke alarm interconnection requirements that flow back to electrical rough-in design.