How to Choose the Right Consumer Unit for Your Home
Most people only think about their consumer unit, or the fuse box as a lot of us still call it, when something trips and won't reset. But with a steady run of rewires, renovations and new builds coming through our trade counters, "what size consumer unit do I need" and "do I need to replace mine" are two of the questions we get asked most. Here's what actually matters.
What a consumer unit actually does
It's the central point where the electricity supply into your home splits into individual circuits: lights, sockets, cooker, shower, and so on, each protected by its own breaker. If a circuit faults, that breaker trips rather than cutting power to the whole house, and rather than letting a fault turn into a fire.
Metal vs plastic: what changed in the regulations
Since Amendment 3 of the 18th Edition wiring regulations (BS 7671), domestic consumer units have had to be made from non-combustible material: in practice, steel rather than the plastic or thermoplastic enclosures that were standard for decades. The change followed a number of house fires traced back to overheating plastic units. If your consumer unit is still plastic, it isn't automatically unsafe, but it no longer meets current guidance, and it's the first thing most electricians will flag on an inspection.
How many ways (circuits) do you actually need
This depends on the size and layout of the property, not just room count. As a rough guide:
A one or two-bed flat typically needs 6-10 ways (lighting circuits, ring finals, cooker, immersion, and a spare way or two for future use).
A three or four-bed house is usually 10-16 ways, once you account for separate upstairs and downstairs lighting, an electric shower, outbuildings, and EV charging.
Always spec at least 2-4 spare ways. It's far cheaper to leave capacity now than to fit a second consumer unit later for a home office, an EV charger or a garden office.
RCD and RCBO protection
Current regulations require RCD (residual current device) protection on almost all circuits in a domestic installation, either as a shared RCD covering several circuits via a split-load board, or as individual RCBOs (a combined MCB and RCD) per circuit. Our companion guide on RCDs, RCBOs and MCBs explainedbreaks down exactly which one you need and where. RCBOs cost more per way but mean a fault on one circuit won't take out anything else in the house, which is worth it for anything supplying a fridge-freezer, alarm system, or home office server.
Signs your existing consumer unit needs replacing
It still uses rewireable fuses (fuse wire) rather than modern breakers.
There's no RCD protection at all on socket circuits.
Scorch marks, a burning smell, or a buzzing sound from the unit.
Breakers trip repeatedly for no obvious reason.
If any of those sound familiar, it's worth reading our guide tosigns your home's electrics need updating, then getting a qualified electrician to take a look.
Need a consumer unit, RCBOs or accessories today? Both our StockportandOldhamtrade counters stock a full range at competitive trade prices, with same-day collection or delivery on in-stock items. Open a trade account for ongoing discounted pricing, or call our teamnow for a free quote and help specifying the right board for your job.
