An electric oven, a cooktop, or a tankless water heater draws far more power than a kettle or a TV, and it's built for sustained operation under load rather than brief bursts. Plugging one of these into a regular outlet on a shared circuit is a common mistake — one that often costs more to fix later than wiring it correctly from the start. Here's why high-power appliances need their own dedicated line, and how to tell if something's wired wrong.
Why a regular outlet isn't enough
An outlet and the cable feeding it are rated for a specific current — typically 16A for a standard outlet circuit, roughly 3.5 kW at 220V. An oven, a 5-8 kW cooktop, a 5-8 kW tankless water heater, or an air conditioner can easily exceed that, especially if the outlet also shares a circuit with other kitchen or bathroom appliances. The result is either the breaker tripping constantly, or worse — the cable and outlet running hot for years because more current is passing through them than they're rated for.
What a "dedicated circuit" actually means
A dedicated circuit is a cable of the correct gauge, run straight from the electrical panel to the appliance, with its own breaker sized for that specific load. It isn't shared with any other outlets or appliances. For high-power equipment, this delivers three things: the cable doesn't overheat because it's rated for that exact current; a fault or overload trips only that one circuit rather than the whole home; and it becomes possible to fit a breaker of the right rating, plus — for wet areas like a water heater — an RCD as well.
What typically needs a dedicated circuit
The list isn't identical for every home, but a dedicated circuit is usually planned for the following appliances.
| Appliance | Typical power draw | Why it needs its own circuit |
|---|---|---|
| Electric oven | 2.5-4 kW | Sustained operation under load, steady high current |
| Electric cooktop | 5-8 kW | One of the highest-draw points in the kitchen |
| Tankless water heater | 5-8 kW | Instant high current on startup, wet zone — needs an RCD |
| Storage water heater | 1.5-2.5 kW | Extended heating cycle, wet zone |
| Air conditioner (split system) | 1-2.5 kW | Startup current above rated draw when the compressor kicks in |
A washing machine and dishwasher are technically power-hungry too, but usually fit within a standard outlet circuit — as long as it isn't already loaded with other appliances nearby.
Signs an appliance is wired incorrectly
There are a few warning signs worth watching for after installing new high-power equipment, or in an older home where an oven or water heater was once connected "whatever way was easiest":
- The breaker trips when the appliance switches on, or after it's been running under load for a while.
- The outlet or the appliance's plug feels noticeably warm after 10-15 minutes of use.
- Lights in the home flicker or dim when the oven and, say, a kettle run at the same time.
- The appliance is plugged in through an extension cord or power strip — for an oven, cooktop, or water heater that's never a fine temporary fix, it's a sign the wiring itself is wrong.
If you notice even one of these, it's worth having an electrician look at the wiring rather than hoping it holds — rewiring the circuit properly costs far less than the consequences of a cable overheating under sustained load.
What to check before buying the appliance
It's far easier to plan a dedicated circuit in advance than to rework it after the appliance is already in place. Before buying high-power equipment, check its rated power draw in the specifications and decide in advance where the line from the panel will run — especially if the kitchen or bathroom renovation isn't finished yet. If the appliance is already bought and installed but was never given its own circuit, it can still be sorted out — an outlet for an electric range, for instance, can be installed and given a dedicated line even in a finished room, it just takes somewhat more work than doing it at the rough-in stage.