The Short Answer
On our estimates, replacing an old fuse box with a modern consumer unit costs about £550 to £850 for a typical house (around 10 circuits, RCBO protection), fitted, tested and certified. A small flat is £450 to £700; a large house £700 to £1,000. The swap usually takes 4 to 8 hours.
Testing sometimes turns up faults in the existing wiring, and the electrician shouldn't fit the new unit until they're fixed (£100 to £500 is a fair allowance). An old fuse box isn't automatically unsafe, though: an EICR tells you whether yours needs replacing.
Consumer unit prices
| Item | Typical cost |
|---|---|
| Small, up to 6 ways (flat) | £450 to £700 |
| Standard, about 10 ways, RCBOs | £550 to £850 |
| Large, 14 ways or more | £700 to £1,000 |
| Fixing faults found on test (allowance) | £100 to £500 |
RCBOs or dual RCD?
- RCBO board: each circuit has its own protection, so a fault only trips that circuit and the rest of the house stays on. It also makes the fault quicker to find.
- Dual RCD (split load): the circuits are split across two RCDs, so a fault takes out every circuit on that side. Cheaper.
- High integrity: two RCDs plus some RCBO slots, a mix of the two.
That's from Electrical2Go's buying guide (an electrical wholesaler). I'd pay the extra for RCBOs, and ask for a few spare ways for an EV charger, a shower or a garden office later.
Why faults can hold the job up
Electrical Safety First's best practice guide for electricians says certain conditions in the existing wiring must be confirmed before a consumer unit is replaced. If they aren't met, the electrician should tell you upgrading is needed and not fit the new unit until the remedial work is done. That's why some quotes come with a "subject to test" line.
Is an old fuse box dangerous?
Not necessarily. Electrical Safety First says older units without RCDs or circuit breakers aren't automatically unsafe, and an EICR will tell you. Check for physical damage, scorching or discolouration. If you have an RCD, it has a "Test" or "T" button; if you don't have one, it recommends plug-in RCDs for the sockets in the meantime. See EICR costs.
Certificates and who can do it
A new circuit, a new consumer unit, or work in a bathroom's special location is notifiable: use an electrician registered with Blue Flame, Certsure (NICEIC and ELECSA), NAPIT or OFTEC, who certifies it, or tell building control. See what you should get at the end. Electrical Safety First says you should get an Electrical Installation Certificate and a Building Regulations Compliance Certificate for a new consumer unit.
Get consumer unit / fuse box quotes
Consumer units are priced by the number of circuits and what testing turns up.
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Frequently asked questions
How much does it cost to replace a fuse box?
On our estimates, about £550 to £850 for a typical house with a 10-way consumer unit, fitted and certified.
How long does it take an electrician to replace a consumer unit?
Usually 4 to 8 hours, longer if testing turns up faults that need fixing first.
Can you sell a house with an old fuse box in the UK?
Yes. There's no rule that you must replace it before selling, and Electrical Safety First says an older unit isn't automatically unsafe. A buyer may ask for an EICR.
Can I change a consumer unit myself?
It's notifiable work, so unless you're registered with Blue Flame, Certsure (NICEIC and ELECSA), NAPIT or OFTEC you'd have to involve building control before starting. Most people use a registered electrician, who certifies it.
How often should a consumer unit be replaced?
There's no set interval. Electrical Safety First recommends an EICR at least every 10 years in a home you own (5 if rented), which tells you whether it needs replacing.
How we priced thisView sources (7, 2 official)
Rules come from the legislation and official guidance, read at source. Prices are our estimates: we check them against trade price data, retailer shelf prices and specialists' price lists, then build them up from their parts so the totals add up. Below are the sources behind the page; the trade price guides we only compare against aren’t listed. Where sources disagreed, we've said so. More on our method.
- OfficialThe Building Regulations 2010, regulation 12(6A) and (9): notifiable electrical work and 'special location' (England), legislation.gov.uk. Checked 14 Oct 2026.
- OfficialThe Building Regulations 2010, Schedule 3: self-certification schemes (para 16, roof coverings), legislation.gov.uk. Checked 15 Oct 2026.
- IndustryYour questions answered, Electrical Safety First. Checked 16 Oct 2026.
- IndustryHome buyers: consumer units and RCDs explained, Electrical Safety First. Checked 16 Oct 2026.
- IndustryBest Practice Guide 1: replacing a consumer unit in residential and similar premises, Electrical Safety First. Checked 16 Oct 2026.
- IndustryDomestic consumer units buying guide, Electrical2Go. Checked 16 Oct 2026.
- IndustryFuse box and consumer unit replacement, British Gas. Checked 15 Oct 2026.
