Replacing an oven or freestanding cooker: electrical checks before you buy

Most oven and cooktop surprises happen on delivery day: the new unit doesn't fit the cavity, the plug doesn't suit the outlet, or the appliance draws more than the old circuit can carry. All three are answered in the installation manual, which most makers publish online. Download it before you buy.

You're looking for three things: the electrical rating, given in amps or kilowatts; whether it plugs in or is hardwired; and the cut-out dimensions and clearances. Send us those details, with a photo of the old appliance's rating plate if you can see it without pulling anything apart, and we can tell you whether it's a straight swap.

Many single wall ovens come with a plug and need only a suitable outlet in or beside the cavity. Check the plug type: some ovens have a plug with a larger earth pin, which won't fit a standard outlet and needs a matching outlet on a suitable circuit. Don't change the plug to suit the wall.

Freestanding cookers, double wall ovens and most electric cooktops are hardwired to a circuit of their own. They usually arrive with a cable and no plug, which is correct. Connecting them is licensed electrical work, and the electrician must give you a Certificate of Electrical Safety, with your copy due within 30 days.

If the old oven was hardwired and the new one has a plug, or the other way round, the connection point changes. That's a small job, but better known before the old unit comes out.

Every cooking circuit has a cable and a breaker sized to protect it. If the new appliance's rating fits within what's there and the connection is in good condition, the job is a changeover. If it draws more, which is common when a single oven becomes a double or a narrow cooktop becomes a wide one, the circuit needs upgrading from the switchboard.

Fitting a bigger breaker to the old cable isn't an option. The breaker is there to protect that cable, and oversizing it removes the protection.

A freestanding cooker combines an oven and cooktop in one unit, so its rating is usually the highest of the lot. Wide cookers in particular can need a heavier circuit than the upright they replace.

Hardwired cooking appliances are usually connected through an isolating switch nearby, so the appliance can be turned off for cleaning or service without going to the switchboard. Check where yours is now. It's often on the wall beside the oven tower or above the bench, and in some older kitchens it's inside a cupboard or missing altogether.

If you're changing the layout or cabinetry, the isolator and the connection point may need to move so they stay reachable and don't end up directly behind the new appliance. That's easy before the new cabinets go in and awkward afterwards.

Wall oven cavities are not all the same. Two ovens with the same nominal width can need different cut-out heights, depths and ventilation gaps. Measure the cavity and compare it with the new oven's installation drawing, not just the brochure size.

For cooktops, the bench cut-out has to match the new model. A larger cooktop means cutting the benchtop, and stone needs a specialist for that, so book them in. A smaller cooktop than the old hole won't work unless the maker offers an adaptor frame or the benchtop is replaced.

Check the clearances to the rangehood and side cabinets too. The manual sets them, and they differ between gas and electric.

A new or reworked cooking circuit usually brings a safety switch with it. Energy Safe Victoria notes the Wiring Rules require additional RCD protection when an existing installation is altered, and says Type AC safety switches can't be installed any more, even as like-for-like replacements.

On a modern board with space, that's straightforward. On an older board that's full or still on ceramic fuses, it can decide whether the circuit simply fits or the board needs work first. We check the board before the new oven arrives, so the kitchen isn't left without one.

Supply rarely limits a single oven swap. It comes into play when the kitchen is part of a bigger electric move, such as induction cooking, heat pump hot water and reverse-cycle heating all at once. That's when the mains and the overall load deserve a look.

Moving from a gas freestanding cooker or cooktop to electric involves two trades. Disconnecting and capping the gas supply is gasfitting work for a licensed gasfitter, and Energy Safe Victoria says it's illegal for unlicensed people to do any gasfitting or electrical work. We run the new circuit and connect the electric appliance, and line our visit up with the gasfitter's.

If you're weighing ceramic against induction, the circuit and board questions are similar, and our induction guide covers the cooktop-specific checks. Either way, most electric cooking appliances run on single-phase power with a dedicated circuit sized to the appliance.