Short answer: The cost of a new consumer unit in London depends on what the testing finds, how many circuits you have, where the meter and board sit, and whether earthing or bonding needs bringing up to standard. A fair quote follows a look at the installation, because faults found during testing must be fixed before a new board can be certified.
Why there is no honest fixed price
You will see fixed prices online for a “fuse box change”. They usually cover the box and a few hours of fitting. The part that changes the bill is what happens when the new board meets your old wiring.
A modern consumer unit protects circuits with RCDs, which switch off when current leaks to earth. Old fuse boxes did not have them. When an old circuit is moved onto RCD protection for the first time, hidden faults that never mattered before suddenly show up. A cable nicked by a picture hook, a damp outside light, a neutral shared between two circuits. Each one trips the new board. The electrician cannot certify the work until those are found and fixed.
So the honest answer is that the price is confirmed after a look at the job. Testing before quoting is what stops surprises on the day.
The cost drivers
| What it depends on | Why it matters | Price |
|---|---|---|
| Test results on existing circuits | Faults must be fixed before sign off | Price confirmed after a look at the job |
| Number of circuits | More ways in the board, more testing | Price confirmed after a look at the job |
| Earthing and bonding | Main earth and bonding to gas and water pipes may need upgrading | Price confirmed after a look at the job |
| Board position | Moving it means extending meter tails and circuits | Price confirmed after a look at the job |
| Surge protection and AFDDs | Extra devices add parts and space | Price confirmed after a look at the job |
| Access | Cupboards under stairs, meter cupboards in communal halls, parking | Price confirmed after a look at the job |
| Part P notification | Certificate through a scheme or building control fee | Price confirmed after a look at the job |
Earthing and bonding deserve a word. The main earth connects your installation to the earth provided by the network. Bonding is the green and yellow cable clamped to the gas and water pipes where they come in. In many older homes the bonding is missing, too thin or clamped to a pipe that has since been replaced with plastic. Current standards expect it to be right, so it often forms part of a board change.
What testing usually finds in Croydon homes
Croydon has a real spread of housing. The VOA stock of properties for 2025 shows 28.4% of homes were built before 1919, 23.5% between the wars, and 43.2% of homes are flats.
That mix shapes the job:
- Victorian terraces in Addiscombe, Thornton Heath and South Norwood. These have been rewired, sometimes more than once. Mixed cable from different decades is common. Extensions at the back often have their own circuits added later, sometimes without paperwork.
- Interwar semis in Purley, Coulsdon and Shirley. Lofts and under floor voids can still hide older cable from a 1950s or 1960s rewire. Electrical Safety First notes that black rubber coated cables were phased out in the 1960s. If testing finds rubber cable, putting a new board on it is not the answer. See our guide to rubber wiring.
- Flats around East and West Croydon, including offices converted to flats. The meter and board are often in a cupboard with little space. Some have a separate landlord supply for the hall lights. Access to the meter cupboard may need the managing agent.
More on the area is on our Croydon electrician page.
Part P and the paperwork you should get
Replacing a consumer unit is notifiable work. That is set out in Approved Document P, which lists “the replacement of a consumer unit” as notifiable. The Planning Portal recommends using an installer registered with a competent person scheme, who can self certify.
At the end you should receive:
- an Electrical Installation Certificate with the test results for every circuit
- a Building Regulations compliance certificate, which comes from the electrician’s scheme or from building control
- a clear label on the board showing what each switch controls
Before work starts, ask the electrician which scheme they are registered with and check the registration on the scheme’s own website. If they are not registered, building control at the London Borough of Croydon must be notified before the work, and their fee applies.
Wiring standard in force now
New work designed from 15 October 2026 must follow BS 7671:2018+A4:2026, as the NICEIC explains. The older version was withdrawn on that date. For a standard house board the change rarely alters the price, but it does mean certificates now show the 2026 version. Our Amendment 4 guide covers what changed.
How to get a quote you can trust
- Ask for a visit and a few test readings before the price.
- Ask what happens if faults turn up on the day, and how they will be priced.
- Check the registration, or ask how building control will be notified.
- Ask which devices are included: RCBOs (a breaker and RCD in one, so one fault only takes out one circuit), surge protection, any AFDDs.
- Get the plan for the day in writing, including how long you will be without power.
Our consumer unit replacement page explains how the visit runs. Your price is a quote on survey, agreed before any work begins.
Quick questions
Why will an electrician not give me a price over the phone?
Because the board is only part of the job. The new unit has to be tested with your existing circuits, and faults on those circuits must be put right before it can be signed off. Nobody can see those faults over the phone.
Does replacing a consumer unit need building regulations approval?
Yes. In England it is notifiable work under Part P. A registered competent person can self certify it. Otherwise the council's building control must be told before work starts.
Can a new consumer unit go where the old fuse box is?
Usually, yes. Moving it costs more because the meter tails (the thick cables from the meter) and every circuit cable have to reach the new spot. In flats the position is often fixed by the meter cupboard.
Will I be without power all day?
The power is off while the board is changed and tested. On a typical house that takes most of a working day. Your electrician should tell you the plan before they start.
Last updated 23 October 2026. Written for homes in London. Rules can change, so check the linked sources for the latest position.