Do I need surge protection on my consumer unit?

What does a surge protector in a consumer unit actually do?

It deals with transient overvoltages: spikes lasting a tiny fraction of a second, from lightning striking the network some distance away or from heavy equipment switching on the supply. Each one is short, but it can be thousands of volts.

The SPD sits in or beside the consumer unit, connected between the live conductors and earth. Under normal voltage it does nothing. When a spike arrives it conducts, sends the surge to earth and clamps the voltage to a level your wiring and equipment can cope with.

What it protects is everything electronic that is wired in: boiler and heating controls, mains smoke alarms, an EV charger, an alarm panel, a solar inverter, and the electronics now inside most cookers, hobs and washing machines. A spike that does not destroy something outright can still shorten its life.

What do the wiring regulations actually say?

The rule changed with Amendment 2 to BS 7671 in 2022, which rewrote the section on transient overvoltages and removed the old risk assessment. As published, regulation 443.4.1 requires surge protection wherever an overvoltage could lead to serious injury or loss of life, the failure of a safety service, or significant financial or data loss.

For every other case, which covers most homes, protection is to be provided unless the owner of the installation declares it is not required because any loss or damage would be tolerable, and accepts the risk. In plain terms, surge protection is the default on new work and leaving it out is your decision to make and put your name to, not the installer’s.

Hager’s guide to that change gives fire and smoke detection as an example of a safety service. If your smoke alarms are mains wired, that is worth thinking about before you decline.

The current edition is BS 7671:2018 with Amendment 4, issued in April 2026, and from 15 October 2026 it is the only current version. Electrical Safety First’s coding guidance, updated for it in August 2026, still points to regulation 443.4.1 for when an SPD is required.

Does a missing SPD fail an EICR?

No. Electrical Safety First’s Best Practice Guide 4, which inspectors use to code observations, lists the absence of an SPD where one is required as a C3, improvement recommended. The same guide says a report with only C3 observations can be given an overall satisfactory result.

So if a report comes back unsatisfactory and the only thing wrong is no surge protection, ask the inspector to explain the code. For a landlord the difference matters: C2s have a legal deadline for remedial work, and a C3 is a recommendation you can plan for.

That is the honest answer, and it is one a contractor keen to sell boards may not give you. An old board with no SPD can still be perfectly safe. What usually makes it unsafe is something else on the report.

If I am having a new consumer unit, should I have one?

Usually, yes. It is the cheapest moment to add one: the board is open, the space is planned in and the device is wired as part of the same job. Most new consumer units are designed with a matching SPD from the same manufacturer, which is the combination the board was tested with.

Leaving it out is your call, and if you do, you will be asked to confirm that decision. If you are not sure, tell us what is wired into the house. A home with mains smoke alarms, an EV charger, solar, a heat pump or someone working from home has more to lose from a spike than a flat with a kettle and a television. Our article on what happens on the day a fuse board is replaced covers the rest of that decision.

Can one be added to my existing board?

Sometimes. It needs a compatible device from the board’s manufacturer, room in the board or space for a small enclosure beside it, very short connections to work properly, and its own protective device. The board itself has to be in good condition and the earthing has to be sound, because an SPD sends the surge to earth.

On an older board that is often where it stops. If there is no compatible device or no room, putting a new device on an old board can cost a good part of what a new board would, for a board you may replace in a few years anyway. In that case our advice is to leave it until the board is changed, unless something sensitive and expensive is wired in now.

Fitting an SPD means working inside the consumer unit, so it is a job for a registered electrician who tests the installation afterwards and issues a certificate. If it turns up bigger problems on the way, see our article on repairing or replacing a fuse board.

Do plug-in surge protectors do the same job?

No. A plug-in surge strip protects whatever is plugged into it, and only that. It does nothing for the fixed wiring or for the boiler, smoke alarms, cooker or charger, which are wired in rather than plugged in.

They work well alongside an SPD for a computer or a television, as a second line close to the equipment. Neither of them is lightning protection. A direct strike on the building is a different problem with a different solution, and no device in a consumer unit is designed to stop it.

What changes the price of surge protection?

On a new board it is a small addition to the job. On its own, these are the things that move it.

• Whether your board has a compatible SPD and the space to fit it.
• Whether a separate enclosure is needed beside the board.
• The state of the earthing, which has to be right first.
• Whether it is done with a board replacement or as a visit on its own.

Send a photo of your consumer unit through our quote page and we will tell you whether adding one makes sense, or read how we approach fuse board replacement.

Questions we get asked about this