Consumer unit upgrades are one of the most commonly recommended and most commonly oversold pieces of domestic electrical work. Some boards need replacing urgently. Others are perfectly serviceable and simply look old. This guide sets out what a board actually does, which findings justify replacement, and which ones justify nothing more than keeping an eye on it.
What the board is there to do
A consumer unit distributes the incoming supply to the circuits in your home and protects each one. It protects against overload and short circuit, and on modern boards it also provides residual current protection, which disconnects quickly when current leaks to earth, for example through a person.
That last function is the one that matters most for personal safety, and it is the function that older boards most often lack entirely.
Findings that genuinely justify replacement
Some conditions are not a matter of preference. If your board matches any of these descriptions, replacement is a reasonable recommendation rather than an upsell.
- Rewireable fuse carriers, with no residual current protection anywhere
- Signs of heat damage, scorching or a burning smell at the board
- Cracked, broken or missing covers leaving live parts accessible
- A board that trips repeatedly and cannot be diagnosed because everything is on one device
- No spare ways and a genuine need for new circuits such as an EV charger
- Obsolete devices that no longer have available replacement parts
Findings that do not, on their own, justify replacement
An old looking board that has split load residual current protection, sound terminations, no heat damage and a satisfactory inspection report is doing its job. Being made ten or fifteen years ago is not a fault. Similarly, a plastic enclosure is not a hazard by itself, though it is a prompt to look at the terminations and the protection arrangement.
If someone recommends a board change without opening the board and testing, treat that recommendation with caution. The recommendation should follow the inspection, not precede it.
What a board change does not fix
A new board does not repair the wiring behind it. If the circuits themselves are deteriorated, if there is rubber or fabric insulation, or if there are existing faults on the cabling, a new board will simply detect those faults more reliably and trip. That is the correct behaviour, but it surprises people who expected new equipment to solve everything.
This is why a proper board change starts with testing the existing circuits. Faults found are either repaired first or reported honestly before the new board goes in.
RCBOs versus a split load board
A split load board groups circuits under shared residual current devices, so a fault on one circuit takes out several. Individual RCBOs protect each circuit separately, so a fault only affects that circuit. RCBOs cost more but make faults far easier to live with and to diagnose.
For most family homes we recommend RCBOs. The additional cost is modest against the total job and the day to day benefit is real.
What happens on the day
A typical board change is a single day for an average house. Power is off for most of it. The existing circuits are tested, the old board removed, the new one installed and each circuit reconnected, identified and tested. Main earthing and bonding are checked and upgraded if inadequate, which is common on older properties.
You should receive an electrical installation certificate and building control notification. If the electrician finds a circuit fault during testing, they should tell you before reconnecting rather than after.
Making the decision
The sensible sequence is an inspection first, a written report of findings second, and a decision third. If the report shows missing residual current protection, damaged equipment or unsafe conditions, replace the board. If it shows a serviceable installation with minor observations, budget for a change in due course and spend the money elsewhere for now.
Planning the work
If you decide to proceed, book it for a day you can be at home without needing power, empty any freezer that cannot cope with a day off or arrange alternative supply for it, and clear access to the board. Ask whether smoke alarm supplies, boiler and any alarm systems will be interrupted, and whether anything needs resetting afterwards. A short conversation about that in advance avoids a surprising evening once the power comes back on.
Common questions
- How old is too old for a fuse board?
- Age alone is not the test. Missing residual current protection, damage or heat marks are what matter.
- Will a new board stop my lights tripping?
- Only if the trip was caused by shared protection. If a circuit has a genuine fault, the new board will still trip.
- Is a plastic board illegal?
- No. Current domestic practice is a non combustible enclosure, but an existing plastic board is not automatically unsafe.
- How long does it take?
- Usually a day for an average house, with power off for most of it.
- Do I get paperwork?
- Yes, an electrical installation certificate and building control notification through the scheme.
We inspect and test before recommending a board change, and we tell you plainly if you do not need one.
Related guides
- What Affects the Cost of a Consumer Unit UpgradeTwo identical-looking boards can be very different jobs once the cover comes off.
- RCD vs RCBO: What the Difference Means at HomeThe difference is not protection quality — it is how much of your house goes dark when something leaks.
- Metal and Plastic Consumer Units ComparedThe move to non-combustible enclosures was a response to real failures, not a fashion.