The rule of thumb
An appliance gets its own circuit when it is fixed in place, draws a lot of current for a long time, or must keep running when something else fails. In practice the threshold is around 2 kW of continuous load, or any appliance hard-wired rather than plugged in. Below that, an ordinary socket circuit is fine.
A dedicated line means one cable from the panel to one appliance, with a breaker sized for that cable and, where needed, its own RCD or RCBO.
The usual list
- Electric stove or hob (5–10 kW). The single largest load in a home; typically 6 mm² and a 32 A breaker, or three phases where available.
- Oven (2.5–4 kW). Separate from the hob even when they sit in the same cabinet, because together they exceed one 16 A line.
- Water heater / boiler (1.5–3 kW). Water plus mains, so 30 mA protection is mandatory and the line is dedicated.
- Washing machine and dishwasher (1.8–2.5 kW). Long cycles at near-full load in a wet room; both leak small currents through their heaters and motors.
- Air conditioner (1.5–3 kW). A motor load with inrush current, so it takes a C-curve breaker that would be wrong for a general socket line.
- Underfloor heating (from 1 kW). Runs for hours at full power and sits under a wet floor.
- EV charger (3.7–11 kW). Hours at full rated current, and it can leak smooth DC, so it needs type B leakage protection.
- Garage or outbuilding. A separate building means a long run, its own sub-panel and often its own earthing arrangement.
What goes wrong when they share
A shared circuit fails in three ways. It trips: the washing machine plus a kettle on one 16 A line is 4 kW, and the breaker eventually gives up mid-cycle. It nuisance-trips the RCD: several appliances each leaking a legal fraction of a milliamp add up until a 30 mA device sees enough. And it heats the cable: a load that sits at 90% of the breaker rating for two hours is exactly what warms insulation, even though nothing ever trips.
PlanMyPanel gives every appliance you tick its own group, sizes the breaker and cable for its nameplate power (cable sizing), and counts continuous loads at full power in the load calculation.