What affects the cost of rewiring a house?

A rewire can mean replacing two failed lighting circuits or every cable in the house. Testing decides which, not the year the house was built. An insulation resistance test on each circuit shows which ones are leaking and which still read well, so ask any quote whether it's based on test results or a guess from the look of the switchboard.

If one circuit fails and the rest are sound, a partial rewire may be the honest answer. If the original rubber cable has failed through the roof, the whole house is probably due. A quote that skips testing either allows for the worst case or leaves you open to extras later.

Cable mostly travels through the roof and under the floor, then drops into the walls. A single-storey weatherboard with a roomy roof and a crawlable subfloor is the easiest case. A low-pitched roof, a concrete slab or a second storey takes longer, because cable has to be fed through closed walls or along new paths.

Double-storey homes are the biggest jump. Reaching upstairs points from the roof is straightforward, but rooms under the upper floor often need small ceiling openings or a route up from below. Ask how each quote plans to reach the ground floor of a two-storey home.

Stud walls in weatherboard and brick veneer homes have a cavity to drop cable into. Solid walls don't, so cable runs in chased channels that need patching, or in surface conduit. Lath and plaster in older homes cracks easily and needs a gentler approach. Each one changes both the labour and the making good.

If a renovation is planned, rewiring while the walls are open removes most of that work. It's the single biggest way to shrink the access side of the job.

A rewire replaces what's there, and most owners add to it: more bedroom and kitchen power points, dedicated circuits for an induction cooktop, air conditioning or an EV charger, data points and outdoor power. Each is cheaper now than later, but each adds parts and labour, so write the list before quoting so every quote prices the same house.

Decide on smoke alarms at the same time. Fire Rescue Victoria's summary says homes built, largely renovated or extended after 1 May 2014 need interconnected, hard-wired smoke alarms. Even where that doesn't apply to your home, running the cable while the roof is being worked is far easier than retrofitting later.

An old fuse board can rarely take the new circuits and their safety switches. Energy Safe Victoria's guidance for electricians says that when a switchboard is replaced, the Wiring Rules require safety switches on all final sub-circuits. A main switchboard replacement is inspected by a Licensed Electrical Inspector before the power goes back on, so it needs scheduling into the job.

Old panels can also contain asbestos. WorkSafe Victoria lists switchboards and their backing boards as a typical location for asbestos-containing materials in buildings built or renovated before the late 1980s. If a panel needs specialist removal, expect it as its own line in the quote.

An empty house is quicker to rewire than one with a family living in it, because there's no packing up and restoring power each evening. Clearing furniture off walls, freeing up the roof access and agreeing which rooms go first all help.

Making good is where quotes differ most. One might include patching openings; another leaves the holes for your plasterer and painter. Ask what's included: patching, painting, ceiling repairs, removal of old cable that can be reached, and the Certificate of Electrical Safety at the end.