The consumer unit — still called the fuse box by most people — is where your electricity is split into circuits and where the devices that protect you from electric shock and fire live. A modern one can cut the power in a fraction of a second when something goes wrong. An old one may not protect you at all.
🔍 Signs You Need a New Consumer Unit
- Rewireable fuses — the old white ceramic fuse holders with wire inside. They work, but give no protection against electric shock.
- No RCD — there’s no button marked “T” or “Test”. RCDs are what save lives if someone touches a live part.
- Wooden backboard, cracked casing or a mix of old parts added over the years.
- Scorch marks, a burning smell, buzzing or crackling — treat this as urgent.
- Your EICR recommends an upgrade, or gives a C2 because sockets have no RCD protection.
- You’re adding an EV charger, solar panels, a battery, an electric shower or a big extension — the old board may not have the space or the right protection.
Lights going off or the power tripping now and then isn’t on its own a reason to replace the board — usually it’s a faulty appliance or circuit. See RCD keeps tripping? or no power to some sockets? first.
🔄 Old Fuse Box vs Modern Consumer Unit
| Old fuse box | Modern consumer unit | |
|---|---|---|
| Overload protection | Rewireable fuses or early breakers | Circuit breakers (MCBs or RCBOs) |
| Shock protection | Often none | 30 mA RCD protection on every circuit |
| Casing | Plastic or wood | Metal (non-combustible) |
| Surge protection | None | Surge protection device (SPD) normally fitted |
| Fire protection (AFDD) | None | Required on socket circuits in HMOs; optional elsewhere |
An RCBO board gives each circuit its own RCD, so a fault on one circuit doesn’t knock out the whole house. It costs a little more than a “dual RCD” board, but it’s the option we recommend for most homes and rentals.
💷 How Much Does a Consumer Unit Replacement Cost in London?
| Job | Typical London price (2026) |
|---|---|
| Standard replacement, up to 10 circuits | £700 – £950 |
| RCBO board with surge protection | £850 – £1,100 |
| Larger board (12–16 ways) or moving its position | £950 – £1,200 |
| Arc fault devices (AFDDs) | Extra per circuit |
These are typical 2026 London prices, and normally include testing, the certificate and Building Control notification. What pushes the price up:
- Faults found during testing — a modern board is more sensitive and can expose old faults (for example damaged cables or borrowed neutrals) that must be fixed before it will stay on.
- Earthing and bonding — missing or undersized earth or bonding to the gas and water pipes must be brought up to standard.
- Moving the board, or a meter tail upgrade.
⚖️ The Rules
- It’s notifiable building work. Under Part P of the Building Regulations, a new consumer unit must be fitted by an electrician registered with a scheme such as NICEIC (who notifies Building Control for you), or inspected by Building Control.
- You get an Electrical Installation Certificate (EIC) on the day, and a Building Regulations compliance certificate by post later. Keep both — you’ll need them when you sell or let.
- The current wiring regulations are BS 7671:2018 with Amendment 4, which became mandatory on 15 October 2026.
- An old fuse box isn’t illegal in itself. But for a rented home, the EICR decides: a C1 or C2 must be fixed within 28 days.
🔧 What Happens on the Day
- Pre-checks: the electrician tests the existing circuits and earthing so there are no surprises.
- Power off: expect to be without electricity for most of the working day — usually 4 to 8 hours. Plan ahead for the fridge and freezer, and anyone working from home.
- New board fitted and every circuit connected and labelled.
- Full testing of each circuit, the RCDs and the earthing.
- Paperwork: the EIC, a clear circuit chart on the board, and Building Control notified.
🏠 For Landlords
- A new consumer unit doesn’t replace your EICR — you still need one every 5 years. Keep the EIC with your safety records.
- HMOs: socket circuits up to 32 A on new or altered work need arc fault detection devices (AFDDs). Make sure your quote includes them.
- Give your tenants written notice of the power-off day, and agree access in advance.
- Combine it with your EICR or remedial work to save a second visit.
🏆 Consumer Unit Replacement with FE Maintenance
- NICEIC qualified — we notify Building Control for you
- Fixed price quote before we start, with testing and the EIC included
- EIC issued the same day; any faults found explained clearly before extra work is done
- Free online client portal — every certificate stored in one place, with expiry alerts. See how it works
We cover North, West and Central London. See our electrical services or ask for a quote.
Typical prices are based on published 2026 London price guides and vary with the property and the condition of the existing wiring. General information based on BS 7671:2018+A4:2026 and Part P of the Building Regulations (England), as of October 2026.
Frequently Asked Questions
Get a Fixed-Price Consumer Unit Quote
NICEIC qualified electricians across North, West and Central London. New consumer unit fitted, tested and certified — Building Control notified for you.
info@femaintenance.com · 171 Crescent Road, Barnet EN4 9RN