Which appliances actually need their own dedicated circuit, and why?

Question

I keep hearing big appliances should be on a "dedicated circuit," but I don't understand which ones actually need one, or why.

Oven, AC, water heater, EV charger, washing machine — which should have their own circuit straight from the board rather than sharing?
What goes wrong if they don't?

This is about per-appliance circuits (different from whether the whole board needs upgrading or whether the supply can take an EV charger). Which need their own, and why?

Bilal H. · Accepted Answer

Short answer: appliances that draw a HIGH and/or CONSTANT load need their own DEDICATED circuit — a cable run straight from the board with its own correctly-rated breaker, not shared with sockets or other appliances. The usual list: the oven/cooker, each AC, the water heater(s), an EV charger, and often the washing machine/dishwasher and any big motor/pump. The reason is simple: these loads are big enough that sharing a circuit would overload it (nuisance tripping at best, overheated cable at worst), and a dedicated circuit lets the cable and breaker be sized exactly for that appliance and isolated on its own. Small stuff (lights, general sockets) is fine grouped on shared circuits.

Which need their own circuit (and why): - Oven / cooker: high continuous draw — must be on its own suitably-rated circuit; sharing would overload it. - Each AC unit: big motor/compressor load, run for hours — dedicated so it doesn't trip everything else and can be isolated. - Water heater(s): a heating element is a heavy, sustained load — dedicated circuit with its own isolator. - EV charger: a large continuous load — always a dedicated circuit (and a supply/load check first). - Washing machine / dishwasher, big pumps: often warrant their own circuit (heavy, motor + heater).

What goes wrong if they share: - Overload & nuisance tripping — the shared breaker keeps cutting out because the combined draw is too high. - Overheated cable/connections — a circuit run hot beyond its rating is a fire risk (the warm-socket problem, scaled up). - No clean isolation — you can't safely work on or isolate one appliance without killing others.

What's fine shared: - General lighting and small-appliance sockets are grouped on shared circuits by design — that's normal and correct.

Common mistake: spurring a big new appliance (extra oven, a heater, an EV charger) off an existing socket/circuit "because it reaches," and overloading it. Big or constant loads get their own properly-sized run — have a licensed electrician add the dedicated circuit from the board. Anyone had nuisance trips that turned out to be a big appliance sharing a circuit it shouldn't?

Raj P. · Answer

This clears it up — I was about to put a second oven on a kitchen socket circuit and it would've overloaded it. The "high or constant load = its own run from the board" rule is the simple test I needed. The EV charger one I'd already learned (it needs the supply checked too), but I hadn't thought about the water heater and big appliances the same way. Makes sense that lights and phone chargers can share but a cooker can't. Getting the dedicated circuit put in properly rather than spurring off something that "reaches."

Hana S. · Answer

On a bigger villa this really matters because you accumulate heavy loads — multiple ACs, ovens, a pool pump, now EV charging — and if they're not each on their own properly-sized circuit you get exactly the nuisance-tripping and hot-cable problems described. When we added loads over the years the electrician put the big ones on dedicated circuits and balanced them across the phases. Sharing a circuit with a heavy appliance is a false economy; the dedicated run is what keeps it safe and trip-free. Worth planning before you add the appliance, not after.

Which appliances actually need their own dedicated circuit, and why?

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