How many circuits should my consumer unit have?

The number of circuits in your consumer unit depends on the size of your home and what appliances you have. A typical 3-bedroom house has: 2–3 lighting circuits (upstairs and downstairs), 2–3 ring main circuits for sockets, a cooker circuit, an immersion heater circuit, and possibly a shower circuit. That's 7–9 circuits minimum. If you add an EV charger, solar panels, underfloor heating, or an outbuilding, each needs its own circuit. Modern best practice is to have more separate circuits — it limits how much is affected when one trips and makes faults easier to find. If your consumer unit has no spare ways (empty slots), an electrician cannot add new circuits without upgrading the whole board. When planning a new consumer unit, always ask for extra spare ways for future use.