As a typical market range, a straightforward consumer unit (fuse box) replacement in London costs somewhere around £450 to £900. The final figure depends on the type of board, how many circuits you have, whether you choose RCBOs and surge protection, and whether the existing wiring needs any remedial work before the new board can be certified.
This guide explains what drives the price, what you should expect to be included, and how to make sure the work is done safely and legally under Part P.
Typical consumer unit replacement costs in London
We don't publish a fixed price list for consumer units because every installation is different, but the figures below reflect typical market ranges for London and the Home Counties. They are a guide only; Polarity Electrics gives a fixed written quote after we have looked at your installation.
| Type of job | Typical market range |
|---|---|
| Straightforward like-for-like swap, dual RCD board, small flat or house | £450 – £900 |
| Full RCBO board with surge protection | Typically higher than a dual RCD board, often £800 – £1,300+ |
| Board replacement plus remedial work on existing circuits | Varies widely depending on faults found |
| Relocating the consumer unit or upgrading the main supply tails | Priced on survey |
If someone quotes you a price well below these ranges, ask what is included. A proper replacement should always include full testing of every circuit, an Electrical Installation Certificate and Building Regulations notification.
What affects the price of a fuse box replacement?
RCBO vs RCD protection
Older "split load" or dual RCD boards group several circuits behind one residual current device (RCD). If a single appliance develops an earth fault, the RCD trips and takes out every circuit on that side of the board, which might mean losing your lights and fridge at the same time.
An RCBO combines an RCD and a circuit breaker in one device, so each circuit is protected individually. A fault on the kitchen sockets only switches off the kitchen sockets. RCBOs cost more per way than standard breakers, so a full RCBO board pushes the price up, but for landlords in particular it reduces nuisance call-outs and makes faults easier to trace.
Surge protection (SPD)
A surge protection device (SPD) helps protect the installation and connected equipment from transient overvoltages, for example from lightning strikes on the network or switching on the supply side. The Wiring Regulations require the electrician to consider surge protection, and in most homes an SPD is now fitted as part of a new consumer unit. It adds a modest amount to the cost and takes up space in the board.
Metal enclosure
Since Amendment 3 to the 17th Edition in 2016, consumer units in homes must have a non-combustible enclosure, which in practice means a metal board. Every new consumer unit we fit meets this requirement. If you still have an old plastic unit, it isn't automatically illegal, but it is a good reason to consider an upgrade, especially if it sits under the stairs or near an escape route.
The condition of your existing wiring
This is the biggest unknown. Modern RCD and RCBO protection is far more sensitive than old rewireable fuses, so faults that went unnoticed for years can show up as soon as the new board goes in. Common issues include:
- Borrowed neutrals, where two circuits share a neutral and trip RCDs
- Low insulation resistance on older cables
- Missing or undersized main earthing and bonding to gas and water pipes
- Damaged accessories or DIY alterations
A competent electrician must test every circuit before connecting it to the new board and cannot certify a board on circuits that fail testing. That is why we will always explain any remedial work, with photos and a clear cost breakdown, before going ahead.
Access and location
Boards in tight cupboards, flats with meters in shared risers, or jobs where the consumer unit needs to move all take longer. If your supply tails or main fuse are undersized, the network operator may also need to be involved.
Signs your consumer unit needs replacing
- You still have rewireable fuses (the type with fuse wire) or a wooden-backed board
- There is no RCD protection on socket circuits
- The unit is plastic and in a location where a fire would block your way out
- Breakers trip frequently, or the board shows scorch marks, buzzing or a burning smell
- You are adding circuits, such as an EV charger, and there is no spare capacity
- An EICR has flagged the board with a C2 or C3 observation
If your report has been marked unsatisfactory, our guide to EICR codes explains what each code means and what needs to happen next.
Part P: why you need a registered electrician
Replacing a consumer unit in a home is notifiable work under Part P of the Building Regulations. The simplest and cheapest way to comply is to use an electrician registered with a competent person scheme such as NICEIC or NAPIT. They self-certify the work and notify building control, and you receive a Building Regulations compliance certificate.
Without that certificate you may run into problems when you sell, remortgage or let the property, and your insurer may ask questions after a claim. Polarity Electrics is an NICEIC Approved Contractor and Part P registered, so notification is included as standard.
What should be included in your quote
- Isolation of the supply and safe removal of the old board
- Supply and installation of a metal consumer unit with the agreed protection (RCD, RCBO, SPD)
- Upgrading main earthing and protective bonding where required
- Full testing of every circuit, with results recorded
- An Electrical Installation Certificate and Part P notification
- Clear labelling of the new board
We include no call-out charge, a 12-month workmanship guarantee and £10M public liability cover on every job. You can read more about how we approach the work on our consumer unit replacement London page.
Landlords: plan around your EICR
For rental properties, it often makes sense to combine a consumer unit upgrade with your next inspection. If your EICR identifies an old board as potentially dangerous, you must complete remedial work within 28 days (or sooner if the report says so) and confirm it in writing to your tenant and the council. See our guide on what to do after an unsatisfactory EICR for the full process.
Get a fixed quote for your consumer unit
Our NICEIC-certified engineers replace consumer units across London, Hertfordshire, Essex, Surrey and the wider Home Counties. Tell us about your property and we will give you a fixed written quote with no hidden extras. Call 0203 908 4790 or book online to arrange a visit.
Frequently asked questions
How much does it cost to replace a fuse box in London?
As a typical market range, a straightforward like-for-like consumer unit swap in London usually costs somewhere around £450 to £900. Boards with all-RCBO protection, surge protection or remedial work on existing circuits cost more, which is why we give a fixed written quote after seeing the installation.
Does a consumer unit replacement need Part P notification?
Yes. Replacing a consumer unit in a home is notifiable work under Part P of the Building Regulations. A registered competent person, such as an NICEIC Approved Contractor, can self-certify the work and notify building control for you.
Is a plastic consumer unit still legal?
Existing plastic consumer units are not automatically illegal, but any new or replacement consumer unit installed in a home must have a non-combustible enclosure, which in practice means metal. An EICR may record an older plastic board as an observation depending on where it is located.
How long does a consumer unit replacement take?
A straightforward swap in a typical home is usually completed in a single working day, with the power off for part of that time. Extra circuits, faults found during testing or a board relocation can add time.
Should I choose RCBOs or a dual RCD board?
RCBOs give each circuit its own protection, so a fault on one circuit will not switch off others. A dual RCD board is cheaper but one fault can trip a whole bank of circuits. Many homeowners and landlords now choose RCBOs for convenience and reliability.