Your consumer unit — more commonly called the fuse box or fuse board — is one of the most important safety components in your home's electrical system. It distributes power to every circuit in the property and contains the protective devices that should disconnect the supply if something goes wrong. When it is working correctly you barely think about it. But when it is outdated, damaged, or insufficient for the demands of a modern home, it can become a real hazard.
Here are seven clear signs that your consumer unit needs replacing, along with an explanation of why each one represents a genuine safety concern and not just a cosmetic issue.
Sign 1: You Have Rewirable Fuses
If your consumer unit contains rewirable fuses — where you need to thread a piece of fuse wire through a ceramic or wooden carrier when a fuse blows — your installation is seriously outdated and needs replacing as a priority. Rewirable fuse boards date from the 1950s and 1960s at the latest. Some properties still have wooden fuse boards that are even older, or boards constructed with materials that in some cases contain asbestos.
The problem with rewirable fuses is threefold. First, they provide far inferior protection compared to modern miniature circuit breakers (MCBs). They react more slowly to faults, which means that by the time the fuse wire melts, more damage may have been done. Second, they can be over-fused — someone frustrated by repeated fuse blowing might fit a thicker piece of fuse wire than is correct for that circuit, removing the protection entirely. Third, they contain no RCD protection whatsoever, which is a separate but equally serious problem we address below.
If you open your consumer unit and see individual coloured ceramic fuse holders with wire running through them, or if you find a bag of fuse wire stored nearby, you have a rewirable fuse board. This is almost certainly a C2 or C1 observation on an EICR and is a strong argument for immediate replacement. An EICR in Exeter will confirm the full extent of the issues, but in most cases where a rewirable board is present, a full consumer unit replacement will be recommended.
Sign 2: No RCD Protection
Residual Current Devices — RCDs — are the single most important safety advancement in domestic electrical installations over the past four decades. An RCD monitors the difference between the current flowing out on the live conductor and returning on the neutral conductor. If it detects even a small imbalance — as small as 30 milliamps — it disconnects the circuit in milliseconds. That speed and sensitivity is what makes it life-saving.
RCDs protect against two of the most serious electrical hazards: electric shock and electrical fire caused by current leaking to earth through a fault or through a person. Without RCD protection, a fault current that would be sufficient to cause a fatal electric shock may flow for long enough to do so before a conventional fuse or MCB operates. With RCD protection, the supply disconnects so fast — typically within 25–40 milliseconds — that the risk of electrocution is drastically reduced.
Modern consumer units must provide RCD protection to final circuits, particularly those supplying socket outlets and outdoor circuits. If your consumer unit has no RCDs at all — you can tell because RCDs have a test button on them marked "T" or "Test" — then your installation is missing a critical layer of protection. This is typically recorded as a C2 observation on an EICR. Even if the MCBs are modern and the unit is not ancient, the absence of RCD protection alone is sufficient reason to replace or upgrade the consumer unit.
Sign 3: Circuits Trip Repeatedly
Occasional tripping of an MCB or RCD is normal — it is doing its job. But if circuits in your property are tripping repeatedly, or if the RCD in your consumer unit trips and takes out a large portion of the property with it on a regular basis, this is a warning sign that needs investigation.
Repeated tripping can indicate a fault on a circuit — a degraded appliance, damaged cable, or failing connection — but it can also indicate that the consumer unit itself is not fit for purpose. Older consumer units with split-load arrangements may have an RCD protecting too many circuits, meaning that a fault on one circuit disconnects lighting, sockets, and kitchen appliances simultaneously. Modern all-RCBO consumer units give each circuit individual protection, so a fault on one circuit disconnects only that circuit and nothing else.
If you are experiencing nuisance tripping, it is important not to ignore it or simply to reset the breaker repeatedly. A persistent fault that is causing tripping needs to be investigated by a qualified electrician. Once the fault is found and remediated, if the consumer unit itself is the reason that faults have an outsized impact on the rest of the installation, replacement to a modern all-RCBO unit should be considered.
Sign 4: Old Wiring Connected to the Board
The condition of the wiring connected to your consumer unit matters as much as the unit itself. If you have an older property and can see the cables feeding the consumer unit — typically visible in the meter cupboard or where the board is mounted — look at the sheath of the cable. If it is rubber-insulated (black and brittle-looking rather than modern grey PVC) or if the cables are very thin by modern standards, this is a concern.
Installing a new consumer unit on old rubber-insulated wiring does not resolve the underlying problem. However, a consumer unit replacement is often the first step, because the old unit may make it difficult or dangerous to carry out the testing required to fully assess the wiring. A qualified electrician will advise you on the condition of the connected wiring as part of the replacement process and will carry out the tests required to determine whether a rewire is also needed.
It is also worth noting that older consumer units were designed for older circuit arrangements. A property that has had new circuits added — kitchen circuits, electric shower circuits, EV charger circuits — may have additional cables terminating in the board that were not part of the original installation. If these additions were not carried out by a qualified electrician and notified under Part P, the quality of the work may be unknown, and an EICR will need to assess whether those circuits are safe.
Sign 5: Burning Smell or Scorch Marks
This is perhaps the most urgent sign on this list. If you notice a burning smell near your consumer unit, or if you can see scorch marks or discolouration on the unit, its enclosure, or the wall around it, this is an emergency that requires immediate action.
A burning smell from a consumer unit typically indicates that a connection has become loose or corroded and is arcing — creating an electrical arc at the point of poor contact. Arcing generates significant heat, can ignite surrounding materials, and is one of the most common causes of electrical fires. Scorch marks are visual evidence that this has already been happening, possibly for some time.
Do not ignore a burning smell from your consumer unit. Do not assume it will resolve itself. If you detect a persistent burning smell near the board, turn off the main switch if it is safe to do so and call an emergency electrician immediately. This is not a situation where you should wait for a scheduled appointment. An emergency fuse board replacement may be required before power can safely be restored to the property.
Sign 6: Physical Damage to the Unit
Consumer units are enclosed in a protective plastic or metal enclosure for good reason — to prevent accidental contact with live components. If that enclosure is cracked, broken, or missing a cover or blanking plate, live conductors or bus bars may be accessible to touch. This is an immediate danger, particularly in households with young children.
Physical damage can result from impact, from attempted DIY modifications, or simply from deterioration over decades. Older plastic enclosures can become brittle and may crack simply from being opened and closed repeatedly. Metal enclosures can rust if there has been condensation or damp nearby. In either case, a damaged enclosure means the unit needs to be replaced.
When carrying out an EICR, an inspector will check the physical condition of the consumer unit as part of the visual inspection. Damage to the enclosure, missing blanking plates, or any situation where live conductors are accessible will result in at minimum a C2 observation, and potentially a C1 if the hazard is immediate. Replacing the unit resolves this entirely, and a modern unit will have a much more robust enclosure than units from twenty or thirty years ago.
Sign 7: A Property Survey or EICR Has Flagged It
Sometimes you do not need to identify the problem yourself. If you have recently had a homebuyer's survey carried out, or if your property has been subject to an EICR inspection, and the electrician or surveyor has recommended that the consumer unit be upgraded, that recommendation should be taken seriously.
Surveyors and electricians make this recommendation on the basis of what they have observed. It may be that the unit is old, lacks RCD protection, contains components that are no longer serviceable, or that the overall installation requires updating and consumer unit replacement is the appropriate starting point. In some cases, mortgage lenders or insurers may require evidence that electrical issues flagged in a survey have been remediated before they will proceed.
If you have received a report recommending consumer unit replacement and are unsure what it means or how urgent it is, the best step is to book a consultation with a NICEIC-registered electrician. They can review the report, inspect the unit, and give you a clear picture of the work required and the timescale in which it should be done. Visit our consumer unit replacement page to book an assessment in Exeter.
What Happens During a Consumer Unit Replacement?
A consumer unit replacement is Part P notifiable work in England, which means it must be carried out by a qualified electrician who is registered with an approved competent person scheme such as NICEIC. The electrician will isolate the supply, remove the old unit, install the new one, connect all circuits, carry out testing to verify the installation is safe, and provide you with an Electrical Installation Certificate on completion. That certificate is an important document — keep it safe as you will need it if you sell the property or require further electrical work in the future.
A standard consumer unit replacement typically takes between three and six hours depending on the number of circuits and the condition of the existing wiring. In most cases it can be completed in a single day, with power restored to the property by early afternoon.