Planning the electrical in a new build or extension

On a new build, electrical decisions get made twice: on paper, then again when the frame is up. Moving a point on a drawing takes a pen. Moving it after plaster means cutting, patching, painting and usually a variation through the builder. Ask for the electrical plan as soon as it exists, and treat the base allowance of points and lights as a first draft.

Under Victoria's Gas Substitution Roadmap, new homes that need a planning permit have had to be all-electric since 1 January 2024, and under the Building and Plumbing Amendment Regulations 2025, all new homes will have to be built all-electric from 1 January 2027. Cooking, hot water and heating all land on the switchboard. That includes Wyndham growth areas such as Truganina, Tarneit, Wyndham Vale and Manor Lakes, where new housing developments are planned.

Extensions start from what's already there: a switchboard, circuits and smoke alarms that the new rooms have to join. In a post-war brick veneer in Altona or a Victorian cottage in Williamstown, that join is often where the real planning sits.

Draw the furniture on the plan first: beds, sofas, the TV wall, the desk, the fridge and the bench appliances you actually use. Points and switches only make sense once you know where things sit, and a double point hidden behind a bedhead or a built-in robe is a common, avoidable mistake.

Then walk an ordinary day on paper. Where do phones charge overnight? Where does the router go, and is it central rather than stuck in a garage corner? For lighting, settle which lights share a switch, put switches on the latch side of doors and plan two-way switching for long halls and stairs. Fittings can be chosen later. Positions can't.

Big fixed loads normally get a dedicated circuit: the oven, the induction cooktop, the hot water system, each air conditioner or the ducted system, and often the dryer, a spa pump or a garage workshop. Each one takes space on the board, so this list sets the switchboard size. The installation sheet for each appliance sets the details, which is why models need choosing early.

Energy Safe Victoria's guidance for electricians says that if an air conditioner manufacturer's specifications require a dedicated circuit or a residual current device, they must be followed. It also says a safety switch is now compulsory on new residential installations, and that the Wiring Rules require an RCD on all final sub-circuits in a home, hot water included. With a safety switch on each circuit, a faulty dishwasher trips itself and leaves the fridge running.

A split system needs power, a control cable, refrigerant pipes and a condensate drain between the indoor head and the outdoor unit. Run inside the frame, the result is a tidy head on the wall. Left until after handover, it's pipe covers down the outside wall or fresh cuts in new plaster.

Mark outdoor unit spots on the site plan now: off the side path, away from bedroom windows and the fence line, and reachable for servicing. For ducted systems, the Victorian Government recommends zones so areas such as daytime living spaces and bedrooms can be heated and cooled separately. Put the zones, return air grille and controller on the same plan as the downlights so they don't fight over the ceiling.

It's two kinds of licensed work. In Victoria, refrigerated air-conditioning work, including any part of a single-head split system, is plumbing work regulated by the Building and Plumbing Commission, and the Australian Refrigeration Council says installing a split system needs a refrigerant handling licence. Energy Safe Victoria lists air conditioning among the electrical work that gets a Certificate of Electrical Safety.

Even if your next car runs on petrol, have a conduit or suitably sized cable run from the switchboard to the garage wall where the car will park, capped and labelled, and leave space on the board for the circuit. Put it on the side of the car's charge port so the lead won't cross the walkway. Doing the same through a finished garage or slab later is a much bigger job.

Decide early between single-phase and three-phase. A typical home charger runs on single-phase, while faster 22 kW chargers need three-phase, and three-phase also makes sense if you expect two EVs, a large ducted system or a workshop. It's far simpler to settle before the connection is arranged.

Add up the dedicated circuits, the air conditioning, a future EV circuit and any solar or battery, then ask for spare space on top. Most appliances, air conditioners and induction cooktops included, run on single-phase, but three-phase makes sense when the finished house has big combined loads such as a large ducted system, two EV chargers or a workshop. Settle the question while the supply is being arranged.

Energy Safe Victoria counts the main switchboard, consumer mains, meter box and main earthing system as prescribed work, along with solar and battery systems. That work needs inspection by a Licensed Electrical Inspector and can't be turned on or left on until it has been inspected, so build the inspection into the timeline.

On an extension, the existing board has to take the new rooms. Energy Safe Victoria notes the Wiring Rules require additional RCD protection where alterations are made, and RCDs on all final sub-circuits if the switchboard is replaced. A regulators' advisory note gives the example that when an existing power circuit is extended, only that altered circuit needs an RCD. Work out which case applies at quote stage.

After rough-in and before insulation and plaster, ask the builder for a walkthrough with the electrician or site supervisor. Bring the marked-up plan, a tape measure and your phone. Stand where the bed and sofa will go, check the TV and bench heights, and look for the air conditioning pipes, the drain and the EV conduit. Don't handle cables. Point, ask and let the trades move things.

Check the smoke alarms while you're there. The Building and Plumbing Commission says alarms must be on or near the ceiling of every storey, located between each bedroom area and the rest of the house. Fire Rescue Victoria's summary says homes built, largely renovated or extended after 1 May 2014 need interconnected, hard-wired alarms on 240-volt mains with a back-up battery.

Before the walls are sheeted, photograph each one with the tape measure in shot. Years later, you'll know where the cables run before you hang shelves or mount a TV.

After fit-off, the paperwork matters. Energy Safe Victoria says a licensed electrician must provide a Certificate of Electrical Safety whenever they complete electrical installation work, and for non-prescribed work you should get a copy within 30 days. File it with the plan and your wall photos.

Bring us in if you want a second look at the builder's plan, if your contract lets you use your own trades for air conditioning or EV pre-wiring, or if you're managing an extension yourself. Total Comfort is a licensed electrical contractor (REC 38187), family-run, based in Altona Meadows, and one local team for electrical, heating and cooling. Send the plans and you'll get honest advice on what to do now and what can wait, plus a free, no-obligation quote.