Short answer
Anything with a heating element or that draws full power for a long time gets its own circuit: washing machine, tumble dryer, dishwasher, hob, water heater, EV charger. Lighting and ordinary sockets may be combined, but split them per floor and keep lighting separate from power.
Why you split circuits at all
Three reasons, in order of importance:
- Preventing overload. One circuit is 16 amps, roughly 3,680 watts. Two heavy appliances at the same time and you are already at the limit.
- Isolating faults. When something fails, you want as little as possible to go off with it. If your whole ground floor is on one circuit, a short circuit in the kitchen also leaves you in the dark in the living room.
- Working without shutting everything down. An electrician working on the bathroom does not need to switch off the fridge.
Points 2 and 3 are exactly why a good layout is worth more than just "enough circuits".
Always a circuit of its own
These are not up for debate:
| Appliance | Why |
|---|---|
| Washing machine | Heating element, draws full power |
| Tumble dryer | Same, and runs for a long time |
| Dishwasher | Same |
| Hob | 7 kW or more with induction |
| Oven (built-in) | 2 to 3 kW, often at the same time as the hob |
| Electric water heater or instantaneous heater | Heating element |
| Bathroom | Zone requirements, and you want to be able to switch it separately |
| EV charger | Must have its own circuit with its own RCD |
| Solar panels (per inverter) | Feeds back, own protection |
| Heat pump | Must not go off because of something else |
| Boiler and mechanical ventilation | Same |
For the EV charger and the heat pump, exactly what is needed is described in more detail in adapting your consumer unit.
What may share
Lighting and ordinary sockets may be combined, but split them sensibly:
- Per floor, not per room. One lighting circuit downstairs, one upstairs.
- Lighting separate from power. If a vacuum cleaner trips a circuit, you do not want to be left in the dark. This is the most practical rule there is and it is the one ignored most often.
- Split the kitchen into two circuits, left and right of the hob. In a modern kitchen the kettle, air fryer and microwave can easily all be on at once.
- Loft and garage separate, because heavy things often get added there later.
- Outdoors separate. Outdoor lighting and garden sockets are the most common cause of an RCD tripping after rain. If that is on its own circuit, you know straight away where the problem is. See also installing outdoor lighting.
How many sockets per circuit
The standard gives no hard maximum, because it is about the power you connect, not the number of sockets. Practical rules of thumb:
- Living room and bedrooms: eight to ten sockets per circuit
- Kitchen: four to six at most, and then two circuits
- Loft or storeroom: depends on what goes on it, but allow for a freezer, a compressor or a workbench
The rule of four per RCD
A maximum of four final circuits may go behind one RCD. That is not advice, it follows from NEN 1010.
In practice that means: with twelve circuits at least three RCDs. And preferably more, because if four circuits are behind one RCD and something fails, those four go off together.
The alternative is RCBOs: one module that is circuit breaker and RCD at once. More expensive in material, but then never more than one circuit goes off at a time. They are my standard.
How to divide sensibly during a renovation
Think from how you use the space, not from the floor plan.
Ask yourself for each room: what will be here in five years? A study that is now a guest room. A garage that gets a second EV charger. A loft where an air conditioner will be fitted.
During a renovation always run one extra empty conduit to the loft and one to the garage. It costs next to nothing while the walls are open anyway, and saves cutting into walls later.
If you want to work this out for your home, go through the circuit planner. It asks what you do in each room and comes up with a layout.
The circuit chart
Every consumer unit should have a readable circuit chart showing which circuit goes where. Not "circuit 7" but "front bedrooms, sockets".
If your circuit chart is no longer right, that is a reason to have it tested. With a fault or a renovation a wrong chart always costs time, and with an electrician time is money.
From my own work
During a renovation in Ulestraten the customer wanted to save money by keeping the kitchen on one circuit. I made two and that cost about € 90 extra. Two years later a Quooker was added and a second oven. With one kitchen circuit that would have meant a new cable run through a tiled wall.
When to call an electrician
During a renovation or a new build, at the stage when the drawing is ready but nothing has been cut into yet. That is the moment when a good layout costs next to nothing, and afterwards a fortune.
If it goes together with a new consumer unit, see consumer unit replacement. Ready to go: request a quote.
Frequently asked questions
Does every room need its own circuit?
No. Lighting and sockets are usually combined per floor or zone. Only heavy users get their own circuit.
How many sockets may go on one circuit?
No hard maximum, it is about power. In practice eight to ten for ordinary rooms, four to six in the kitchen.
Why does the washing machine need its own circuit?
Because of the heating element, which draws full power as soon as the water heats up. Together with another heavy appliance the circuit trips.
How many circuits behind one RCD?
A maximum of four final circuits.
Does outdoor lighting need its own circuit?
It is not required, but it is sensible. Outdoors is the most common cause of leakage current and with its own circuit you find it straight away.
My circuit chart is no longer right, does that matter?
Not dangerous, but awkward. With a fault it costs time to search. Testing and filling it in again is usually about an hour's work.
Further reading
Which consumer unit brand should you choose? Hager, Schneider, ABB and the rest
All brands are equally safe. The difference is whether you can still add a circuit in eight years' time, and that is exactly what nobody tells you.
Connecting an RCD: how it should be done and why it is not a DIY job
Where it sits in the chain, how it works and the neutral fault that explains nine out of ten RCDs that trip at random.
Meter cupboard dimensions: what fits and what are the requirements?
The standard sizes, how many modules really fit and the three things you need to measure before you order a bigger consumer unit.
Questions and comments
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