On this page
- What the cost of a new fuse box and fitting includes
- What changes a consumer unit installation cost
- A new consumer unit with old wiring: the wiring sets the price
- Testing comes before the replacement
- Three possible outcomes after testing
- Nothing forces an upgrade, but a new board must meet today's rules
- The two certificates you should receive
The short version
- Consumer unit replacement in London costs from £400, typically £400–£700 including VAT.
- Old wiring, not the board, is what usually changes the price.
- A new RCD board trips on faults an old fuse box ignored, so test the circuits first.
- Rubber-insulated or lead-sheathed cables should be replaced before a new consumer unit goes in.
- Replacing a consumer unit is notifiable in England: expect an EIC and a Building Regulations certificate.
Replacing a consumer unit, or fuse box, in London costs from £400, typically £400–£700 including VAT, for a straight swap in a typical home. The price covers the new board, testing every circuit and the certificates. What moves it is rarely the board itself: it is whether the existing wiring passes the tests a modern RCD board depends on.
| Job | Guide price (VAT included) |
|---|---|
| New consumer unit, supplied and fitted | from £400 (typically £400–£700) |
| EICR before the work, 1-bed flat | from £120 |
| Tracing a fault on an existing circuit | from £100 |
| Partial rewire, where a circuit cannot be saved | from £2,000 |
These are guide prices, not fixed quotes. The figure for your home is confirmed once the installation has been tested, for the reason explained below.
What the cost of a new fuse box and fitting includes
Most people search for a fuse box and most electricians price a consumer unit. It is the same job: replacing the board where every circuit in your home starts. The new consumer unit cost you are quoted should include:
- A new consumer unit in a non-combustible metal enclosure
- 30 mA RCD protection for the socket and lighting circuits that require it
- Surge protection, where the regulations call for it
- Testing every circuit, with the results recorded
- An Electrical Installation Certificate, and notification to building control
What changes a consumer unit installation cost
Two jobs that look the same on paper can be priced differently. These are the things that move the figure:
- The condition of the wiring, which only testing shows
- How many circuits there are to test and reconnect
- Whether your home needs surge protection
- Earthing, bonding or meter tails that need upgrading first
- Moving the board or adding new circuits at the same time
The earthing check is not optional. Industry guidance says the installer must confirm the main earthing, the main protective bonding and the meter tails are adequate before changing the board, and should not go ahead until any shortfall is put right.
A new consumer unit with old wiring: the wiring sets the price
Why an old fuse box hides faults
An old fuse box with rewireable fuses protects against overload, but it has no RCD. A small fault can sit in the wiring for years without anyone noticing, because nothing on that board is built to detect it.
What a new board does differently
A new board's 30 mA RCDs trip on current leaking to earth. A damaged cable, a neutral shared between two circuits or damp in a fitting, all ignored by the old fuses, will trip the new board the day it goes in.
Electrical industry guidance is plain about what happens next. A faulty circuit is repaired, or it stays disconnected until it is. It is not connected to the new board as it stands.
Old wiring that changes the job
Some older wiring needs more than a repair before a new board can go in. This is what the industry guidance on replacing a consumer unit recommends:
| What the survey finds | What the guidance recommends |
|---|---|
| Rubber-insulated or lead-sheathed cables | Replace the cables before the board is changed, because handling them during the swap is likely to damage the old insulation |
| Lighting circuits with no earth, usual in homes wired before 1966 | Add an earth, or reconnect only once every metal light fitting and switch on the circuit is swapped for an all-insulated (Class II) one, with a warning label at the board |
| Low insulation readings or shared neutrals | Trace and repair them first, or leave that circuit disconnected |
None of this shows on the front of the board. It turns up in testing, and it is priced as fault finding or a partial rewire, as the outcomes table below sets out.
Testing comes before the replacement
Because the wiring decides the job, the installation should be tested before a replacement is booked. That means an EICR, or at the least a survey including insulation resistance tests on every circuit. Contractor guidance says the work should not go ahead without one.
If you already have a recent EICR, read it first. Any C2 or FI observations, or notes about low insulation readings, show what a new board is likely to expose. Our guide to what an EICR report tells you explains the codes.
An EICR in London costs from £120 for a 1-bed flat, including VAT. When you ask anyone for a consumer unit price, ask whether they will test first.
Three possible outcomes after testing
| What testing finds | What happens | Guide price (VAT included) |
|---|---|---|
| The circuits test well | The board is replaced like for like | from £400, typically £400–£700 |
| One or two circuits have faults | The faults are traced and repaired, then the board goes in | the board, plus fault finding from £100 |
| A circuit cannot be saved | That circuit is rewired, or stays disconnected until it is | partial rewire from £2,000 |
Whatever testing finds, any extra work is quoted in writing before it starts, so the figure never changes halfway through the job.
Nothing forces an upgrade, but a new board must meet today's rules
Homeowners and landlords
No law makes a homeowner replace a working fuse box. The rules apply when work is done: new work must meet BS 7671, the UK wiring regulations, and must not leave the installation less safe than before. Our guide to what is dangerous and what is legal about an old fuse box covers when keeping yours is reasonable.
Landlords are in a different position. An EICR may record missing RCD protection as an observation, and anything coded C1, C2 or FI has to be put right within 28 days.
What a new domestic board must have
- A non-combustible enclosure, in practice steel, required in homes since January 2016
- 30 mA RCD protection for socket circuits rated up to 32 A and for lighting circuits
- Surge protection in most homes, unless what it protects does not justify the cost
The two certificates you should receive
Replacing a consumer unit is notifiable work under Part P of the Building Regulations in England. That means two documents, issued at two different points:
- An Electrical Installation Certificate (EIC) when the work is finished, confirming the new board and its circuits were tested to BS 7671.
- A Building Regulations compliance certificate within 30 days, after the installer's registration scheme has notified building control.
Keep both. A buyer's solicitor, a letting agent or an insurer may ask for them. Work by an installer who is not registered with a scheme has to be notified to building control separately, before it starts.
For consumer unit replacement in London, call 07727 619854 or see our electricians in London. We are NICEIC approved, so the testing, the certificate and the building control notification are part of the job.
Frequently asked questions
Yes, in everyday use. Fuse box is the older name, from boards that used fuses; a modern consumer unit uses circuit breakers and RCDs instead. Replacing either is the same job, priced the same way.
Our guide prices are for London homes: from £400, typically £400–£700 including VAT. Anywhere in the UK, the final figure turns on the same things: the condition of the wiring, how many circuits there are, and whether the earthing or bonding needs upgrading first.
An Electrical Installation Certificate when the work is finished, and a Building Regulations compliance certificate within 30 days. Replacing a consumer unit is notifiable work in England, so a registered installer notifies building control for you.
Replacing a fuse box is notifiable work in England. If you do it yourself, or use an installer who is not registered with a scheme, you have to contact a building control body before the work starts. A registered electrician handles the notification and certificate for you.