Your consumer unit – often still called the fuse box – is the control centre of your home’s electrics. A consumer unit replacement in the UK usually costs £450 to £800 for a standard home, or £800 to £1,200 for a fully RCBO-protected board with surge protection, and is one of the most effective electrical safety upgrades you can make if you still have old rewireable fuses or no RCD protection.
Replacing a consumer unit is notifiable work under Part P in England and Wales, so it must be carried out by a registered electrician who tests the whole installation, issues an Electrical Installation Certificate and notifies building control. Here is what affects the price, what the different protective devices do and what to expect on the day.
Fuse box or consumer unit: what’s the difference?
Older fuse boxes use fuse wire or cartridge fuses that melt when a circuit overloads. They protect cables, but they do little to protect people from electric shock. A modern consumer unit uses circuit breakers that switch off instantly, plus residual current protection that detects dangerous leakage to earth – the kind that happens when someone touches a live part.
Signs your consumer unit needs replacing
The protection inside a modern board
- MCB – Miniature Circuit Breaker
- Replaces the old fuse. Trips when a circuit is overloaded or short-circuits.
- RCD – Residual Current Device
- Cuts power in a fraction of a second if current leaks to earth. Often protects a group of circuits.
- RCBO
- Combines an MCB and RCD for each individual circuit, so one fault does not switch off half the house.
- SPD – Surge Protection Device
- Protects electronics from voltage spikes. Usually recommended under current wiring regulations.
- AFDD – Arc Fault Detection Device
- Detects dangerous arcing in damaged cables. Optional in most homes, but increasingly offered.
Consumer unit replacement prices
Costs rise if the electrician finds faults that must be fixed before the new board can be connected, such as missing earthing, damaged cables or circuits that fail insulation tests. A good electrician will warn you about this possibility before starting.
Why testing comes first
A new RCD-protected board is very sensitive. If an old circuit has a hidden fault, the new device will trip immediately. That is why reputable electricians carry out pre-installation tests and may recommend repairs before the swap. It can feel like an extra cost, but it means the problem is found safely rather than the board tripping every evening.
Planning ahead for solar, EV chargers and heat pumps
If you are thinking about solar panels, a battery, an electric car charger or a heat pump in the next few years, tell your electrician now. Each of these needs its own dedicated circuit and protection, and some require specific types of RCD. Choosing a board with spare ways, a suitable main switch rating and room for surge protection means you will not have to replace the consumer unit again when you add low-carbon technology. It also helps the installer check whether your incoming supply and main fuse are large enough for the extra demand.
What happens on the day
- Power is switched off at the main isolator – usually for half a day.
- The old unit is removed and circuits are labelled.
- The new metal-clad consumer unit is fitted and circuits reconnected.
- Main earthing and bonding to gas and water pipes are checked or upgraded.
- Every circuit is tested and the RCDs trip-tested.
- You receive the certificate, and building control notification follows.
Questions to ask before you choose a board
- Will every circuit have its own RCBO, or will circuits share RCDs?
- Is surge protection included, and if not, why not?
- How many spare ways will be left for future circuits?
- What happens, and what will it cost, if faults are found during testing?
- Which certificate will I receive, and when will building control be notified?
Simple checks you can do yourself
- Press the “T” test button on each RCD every few months – it should trip and reset.
- Keep the area around the board clear and dry.
- Make sure every circuit is clearly labelled.
- Never open the cover or replace parts yourself.
Prices reflect typical UK installer quotes; terms follow current wiring regulations.
Independent guide – not linked to any electrician or manufacturer.