Signs your fuse box needs replacing
Rewireable fuses, no RCD, a plastic case, scorch marks or a wooden backboard? Seven signs your fuse box may need replacing, what you can safely check, and what a new one costs.
A fuse box probably needs replacing if it has rewirable fuses, no RCD protection, a plastic case, scorch marks, a wooden backboard, or breakers that trip for no reason. None of these means it is dangerous today, but they show it is behind current safety standards. A new metal consumer unit starts from around £495.
- Rewirable fuses or no RCD are the clearest signs
- Metal units have been required since 2016
- New consumer unit from £495 including VAT
- Half a day's work, certificate and notification included
Fuse box vs consumer unit
Everyone calls it the fuse box. The trade calls it a consumer unit, and you will see that name on quotes and certificates. They are the same thing: the box, usually near the front door or under the stairs, where the electricity supply comes into your home and is split into separate circuits for the lights, the sockets, the cooker, the shower and so on. Each circuit has a protective device in the box that cuts the power if too much current flows.
In an old box those devices are fuses, a thin wire that melts. In a modern consumer unit they are circuit breakers, which are switches that trip and can be reset, plus RCDs. An RCD is a residual current device, and it does a different job: it trips in a fraction of a second if electricity leaks out of a circuit, which is what happens when someone touches something live. The newest units use RCBOs, a circuit breaker and an RCD combined in one switch for every circuit, so a fault in the garden does not take out the fridge.
I have been looking at fuse boxes on the Fylde coast for over twenty years, and the spread is enormous. We still find 1960s boards in Cleveleys bungalows that have never been touched, and we find units fitted last year. Age on its own is not the problem. Here is what is.
Seven signs it’s time
Rewireable fuses
If the fuses are ceramic or Bakelite holders with a visible length of fuse wire, and there is a card of spare wire pinned inside the lid, the box is likely forty years old or more. Rewireable fuses work, but they are slow, they can be rewired with the wrong wire, and they offer no protection against electric shock.
No RCD protection
Look for a switch marked RCD, or a row of switches with a small “T” or “test” button. If there is none, nothing in the house will cut the power quickly if a person becomes part of the circuit. The current wiring regulations, BS 7671:2018+A2:2022, expect RCD protection on almost every circuit in a home. A box without it is not illegal, but it is a long way behind.
A plastic case
New consumer units in homes have had to be made of a non-combustible material, which in practice means steel, since January 2016. The change was made because a loose connection inside a plastic unit can start a fire that the plastic then feeds. An existing plastic unit is not automatically unsafe, and an EICR will usually give it a C3, improvement recommended, rather than anything more serious. But if it is being replaced for any other reason, it will be replaced with a metal one.
A wooden backboard
Many older installations have the fuse box screwed to a wooden board, sometimes with the main fuse and meter alongside. Wood, old rubber cable and a loose connection are not a combination we like to see, and the board often hides cable that has gone brittle.
Heat, scorch marks or a smell
Brown or black marks around a fuse holder or on the case, a warm cover, or a fishy or burning plastic smell near the box all mean a connection is overheating. This is the one sign on the list that is urgent.
Buzzing or crackling
A faint hum from a modern unit can be normal. A buzz that comes and goes, or any crackling, is a loose connection or a failing device and needs looking at.
Frequent tripping
A breaker that trips once because the toaster died is doing its job. A breaker or RCD that trips every few days, or an old fuse that keeps blowing, is telling you something is wrong on that circuit or in the box itself. It will not fix itself.
Taken together, two or three of these on one box usually tip the balance towards replacing it rather than patching it.
What you can safely check yourself
Everything on the list above can be checked by looking. Open the outer lid if it has one, which is designed to be opened by you, and look at what is behind it. Do not remove any cover that needs a screwdriver, and do not touch terminals or cables.
Press the test button on any RCD. The power to the circuits it protects should go off instantly, and you reset it by pushing the switch back up. If it does not trip, or will not reset, that is a job for an electrician. The manufacturers suggest doing this test every few months.
Take a photo of the open box. If you ring us, a photo of the fuse box and one of the labels on the circuits tells us most of what we need before we visit.
That is the limit. Anything that involves taking the front cover off means the box is live inside, and the main switch does not make the incoming supply safe. If you smell burning, switch the main switch off and ring an electrician.
What replacement involves
A new consumer unit is not just a swap. The wiring regulations require the existing circuits to be tested before they are connected to the new unit, because a new RCD will trip on a fault that an old fuse has quietly ignored for years. We test every circuit first and tell you if anything needs fixing, so there are no surprises on the day.
Replacing a consumer unit is notifiable work under Part P of the Building Regulations in England. That means it has to be either done by an electrician registered with a competent person scheme, who notifies the council for you, or inspected by building control. Our Part P guide explains how this works. You get two documents when we finish: an Electrical Installation Certificate recording the tests, and a Building Regulations Compliance Certificate from the scheme, which arrives by post or email a few weeks later. Keep both. Your solicitor will ask for them when you sell.
The job takes us most of a day in a typical house. The power is off for several hours, so we agree a start time that suits you and label every circuit before we leave.
Rough costs
Our consumer unit replacements start from £495 including VAT. That price covers a metal ten-way unit with RCBOs on every circuit, the testing beforehand, the certificate and the Part P notification. A bigger house with more circuits costs more, as does a surge protection device, which we recommend on homes with a lot of electronics, and any remedial work on the existing circuits that the testing turns up. If the earthing or bonding to the gas and water pipes is missing, that has to be put right at the same time, and we price it separately so you can see what you are paying for.
We give a written quote before we start, and if the old box is fine and only needs a new RCD or a tidy, we will tell you that instead.
When it’s urgent
Most fuse box replacements can be planned. A few cannot. If the box is hot to touch, if there are fresh scorch marks, if you can smell burning plastic or hear crackling, or if a breaker will not reset and you can see discolouration around it, switch the main switch off, leave the lid open so you can see it, and ring an electrician the same day. Do not leave the house empty with the supply on. We run an emergency call-out for exactly this on the same number, seven days a week.
Need a hand?
If anything on this page sounds like your fuse box, our consumer unit upgrades page explains what we fit, what changes the price and how the day goes. Send us a photo of the open box through our contact page and we will tell you honestly whether it needs replacing.
