What size consumer unit do I need?

What Size Consumer Unit Do I Need? Your consumer unit (also called a fuse board or distribution board) is the heart of your home's electrical system. Choosing the right size means having enough circuit breaker slots — called ways — for every circuit in your home, plus room for future additions. What Does 'Size' Actually Mean? The size of a consumer unit refers to the number of ways it has — each way holds one MCB (miniature circuit breaker) or one RCBO. It does not refer to physical dimensions, though larger units are physically bigger. How Many Ways Do Typical Homes Need? 1–2 bedroom flat: 6–8 ways 2–3 bedroom house: 10–12 ways 4 bedroom house: 12–14 ways Large or extended home: 14–16 ways or a dual split-load board What Circuits Count Toward the Total? Every separate circuit needs its own way. Common circuits include: Lighting — typically one per floor Ring main sockets — usually one per floor Cooker or oven circuit Shower circuit Immersion heater Garage or outbuilding EV charger Solar PV or battery storage Underfloor heating Alarm systems or CCTV What Should You Check? You can safely count your existing circuits by: 1. Looking at the number of breakers already in your current consumer unit 2. Checking if any spaces are already full or if breakers are doubled up (a sign the board is too small) 3. Thinking about planned additions in the next 5–10 years Always Leave Spare Capacity Electricians recommend leaving at least 2–4 spare ways beyond your current needs. Technology changes — EV charging alone could add 1–2 circuits. When to Call an Electrician If you are replacing an old fuse board If you are adding any new circuits If your current board is full If you want to future-proof for solar, EV, or smart home systems Consumer unit installation is notifiable work under Part P of the Building Regulations. Always use a registered electrician.