Old fuses, no RCD, constant tripping or scorch marks? Seven honest signs your fuse board (consumer unit) is due an upgrade, and what to do next.
You probably need a new fuse board if it still uses old rewireable fuses, has no RCD protection, shows any sign of heat damage, or trips constantly for no clear reason.
A modern consumer unit gives you the shock and fire protection that a pre-2000s board simply cannot. Here are the seven signs it is time to upgrade.
Your fuse board, also called the consumer unit, is the box that splits your electricity into circuits and cuts the power the instant something goes wrong.
When someone asks us do I need a new fuse board, it is usually because theirs keeps tripping, looks old, or an electrician has mentioned it in passing. Below are the exact signs we look for on jobs around South Yorkshire, what each one means, and how urgent it is.
Do I need a new fuse board? The seven signs
Not every old board needs ripping out tomorrow. But if you recognise more than one or two of these, it is worth getting it looked at properly.
1. It still uses old rewireable fuses
If your board has little ceramic or plastic fuse holders with a strip of fuse wire inside, rather than switches that flick up and down, it is an old rewireable board.
These do their basic job, but they are slow to disconnect a fault, easy to fit with the wrong fuse wire, and offer none of the shock protection built into modern units. A board like this is usually decades old and near the end of its useful life.
2. There is no RCD protection
An RCD, or residual current device, is the part that protects you from a fatal electric shock. It cuts the power in a fraction of a second if current leaks to earth, for example through a damaged cable or a faulty appliance.
If your board has no RCD at all, or only protects some circuits, it does not meet the standard expected of a modern installation. Current regulations expect RCD protection on most circuits, which makes this one of the strongest reasons to upgrade.
3. It is an old plastic board, especially under the stairs
Since 2016, domestic consumer units have had to be made of non-combustible material, in practice a steel enclosure, so that a loose connection inside cannot set fire to the box.
Older plastic boards are still common, and they are a particular concern when fitted under wooden stairs or in a hallway, which is often the escape route from the house. A plastic board is not an emergency on its own, but combined with any heat damage it moves up the list quickly.
4. It trips constantly, or never trips at all
Nuisance tripping is a symptom, not just an annoyance. It can mean a genuine fault on a circuit, an overloaded board, or ageing components that can no longer tell a fault from normal use.
Equally, a board that never trips despite obvious problems may simply not be protecting you at all.
If your lights also flicker or dip when appliances switch on, that is worth reading about in our guide on why your lights flicker. Either way, constant tripping is your installation asking for attention.
5. There are signs of heat: scorch marks, a burning smell, or a warm board
This is the one to take seriously today, not next month. Brown scorch marks around the fuses, a faint smell of hot plastic, or a board that feels warm to the touch all point to loose or overheating connections, and that is a fire risk.
If you notice any of these, stop using the affected circuits and call an electrician. Do not wait for a convenient time.
6. You are adding load: an EV charger, electric shower, solar or an extension
Old boards often have no spare ways left, and cannot provide the individual RCD or RCBO protection that new circuits need.
Adding an EV charger, an electric shower, a solar and battery system or a full extension is usually the moment a tired board has to be upgraded to cope safely. If you are planning any of this, it is cheaper to sort the board as part of the project than to bolt it on afterwards.
7. It failed, or was flagged, on an EICR
An Electrical Installation Condition Report often puts the spotlight on the consumer unit. Old boards regularly pick up C2, potentially dangerous, codes for missing RCD protection or a combustible enclosure.
If your EICR came back unsatisfactory because of the board, a new consumer unit is usually what clears it. It is one of the most common jobs we pick up after an EICR and electrical test.
What does a new consumer unit actually give you?
A modern consumer unit is not just a tidier box. Inside, you typically get RCD or RCBO protection on each circuit, so a fault on one circuit does not plunge the whole house into darkness; modern breakers that trip cleanly on overload; a steel enclosure that contains any heat; and a surge protection device, now required under the wiring regulations, to guard sensitive electronics against spikes. It is a genuine step up in both safety and everyday reliability.
How much does it cost to replace a fuse board?
As a rough guide, a domestic consumer unit replacement in 2026 typically runs from around £350 to £700, depending on the board, the number of circuits and where it is fitted. These are typical market figures, not a fixed FRM price.
Two honest caveats. First, once the new board goes in, every circuit is tested, and any pre-existing faults that were hiding behind the old board have to be put right for the installation to be certified, which can add to the job.
Second, the price should always include that testing and certification, not just swapping the box. We give you a fixed quote up front after a quick look, so you know the full number before we start.
Can I replace a fuse board myself?
No. In England and Wales, replacing a consumer unit is notifiable work under Part P of the Building Regulations.
It must be carried out by a qualified electrician, then tested and certified, and either done by a registered competent person or notified to building control.
Beyond the legal side, it is live mains work with a real risk of electrocution and fire. This is not a DIY job.
What happens when FRM replaces your consumer unit
If you ring us and say you need a new fuse board, the first thing we will say is: let's test it first. Every board change we do starts with a full EICR, before we even price the job.
It tells us exactly what is going on behind the old board, the circuits, the earthing, the bonding - so any faults are found up front, not halfway through the swap.
We then quote the new board and any remedial work together as one job, so the price you get is the real one. Nine times out of ten, once we explain why, people are glad we did it that way.
A new consumer unit is only as good as the earthing behind it. As part of the EICR we check that your main earth and the bonding to your gas and water pipework are present, correctly sized and up to current standards.
Older homes often have bonding that is undersized or missing altogether, and a new board cannot be certified until that is put right.
It is usually a quick and inexpensive fix, and because it is picked up during testing, it is sorted as part of the same visit rather than becoming a problem on the day.
On the day, we isolate the supply, fit a new metal consumer unit with RCBO protection and surge protection as standard, then test and certify every circuit to BS 7671 before handing over the paperwork.
As an NICEIC-approved, family-run team based in Wath upon Dearne, we do the whole job in-house.
We upgrade fuse boards across the Dearne Valley and the wider South Yorkshire area. You can see our full consumer unit upgrades and rewires, find your local electrician in Wath upon Dearne, or browse all the areas we cover.
If any of the seven signs sound familiar, get in touch for a no-obligation chat. A quick phone call is usually all it takes to tell you whether your board needs booking in for a test, or simply keeping an eye on.
Frequently asked questions
Is a fuse board the same as a consumer unit?
Yes. They are two names for the same thing: the board that houses your fuses or circuit breakers. Older ones tend to be called fuse boards, newer ones consumer units, but people use both words for either.
How long does it take to replace a fuse board?
Most domestic consumer unit replacements take around half a day. Older or larger installations, or ones that need remedial work to pass testing, can take longer.
Will my power be off while the work is done?
Yes. The supply has to be isolated while the new board is fitted and tested, so expect to be without power for a few hours. We plan the timing with you so it causes the least disruption.
Do I need a new fuse board to fit an EV charger?
Sometimes. A charger needs its own protected circuit, and many older boards have no spare way or the right type of RCD for one. If yours is full or dated, a new consumer unit is often the tidiest way to add one safely.
Does a new consumer unit come with a certificate?
Yes. A proper installation includes an Electrical Installation Certificate and, in England and Wales, notification to building control. Keep the certificate safe, as you will want it for an EICR, a house sale or an insurance claim.
The bottom line
A fuse board rarely fails all at once. It ages quietly, until an added load or a failed EICR forces the issue.
If yours is ticking two or three of these boxes, it is better to plan the upgrade on your own terms than to let a tripped circuit on a cold evening make the decision for you.
