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What a Surge Actually Is
A surge is a very short spike in voltage. It lasts a fraction of a second, and in that fraction it can push far more voltage down the wire than anything in your house is built to take.
Most people picture lightning. Lightning does cause them, but it rarely needs a direct hit. A strike a few streets away can put a spike onto the network that arrives at your consumer unit moments later.
The more common cause is duller. The grid switches. Large motors on the same street start and stop. Every one of those events sends a small spike down the line. Your appliances shrug most of them off. It is the occasional large one that does damage.
A surge protection device, an SPD, sits in your consumer unit and diverts that spike to earth before it reaches anything expensive.
What the Regulations Actually Say
This is where most of the confusion comes from, so it is worth being precise.
Section 722 of BS 7671 is the part that covers electric vehicle charging. It does not mention surge protection. People assume there is an EV specific rule. There is not.
The requirement comes from Regulation 443.4, in Chapter 44, which applies to the installation as a whole. It says protection against transient overvoltage is required where a surge could cause serious injury or loss of life, could stop a safety service working, or could cause significant financial or data loss.
For everything outside those categories, BS 7671 uses a risk assessment. If the assessment shows the cost of protection is not justified by what is being protected, an SPD can be left out, and that decision gets recorded.
Amendment 2 to the 18th Edition, published in March 2022 and mandatory for new work from 27 March 2023, tightened the wording around overvoltage protection. It did not remove the risk assessment route for single dwellings, and it did not create an EV specific rule.
In practice most installers now fit an SPD by default on domestic work rather than rely on a risk assessment. That is a judgement about what is sensible, not a legal obligation on every job, and any electrician who tells you the regulations force one onto every EV install is overstating it.
Does Your Charger Have One Built In?
Some do, and it does not remove the need for an SPD.
myenergi are the clearest on this. They say the zappi carries built in surge protection as standard, and in the same paragraph they say your installer should still fit a separate device: “wiring regulations dictate that you should still fit a surge protection device (SPD) when installing any new EV charger.”
For other brands, do not assume it either way. Built in protection is not always stated on the datasheet, and where it exists it protects the charger, not your house.
That is the part worth understanding. An SPD fitted for the charger is not really fitted for the charger. It sits at the origin of the installation, upstream of everything, and protects the boiler, the heat pump, the router and the television at the same time. Protection inside the charger can only ever defend the charger.
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Why It Matters More Than It Used To
Twenty years ago a surge took out a kettle. The things it takes out now are different.
An EV charger is a connected device with a circuit board in it. So is a solar inverter, a battery, a heat pump and a smart meter. Modern homes hold more electronics behind the consumer unit than they ever have, and electronics are what surges damage.
There is a second reason, and it is the one people forget. A charger that fails from a surge is not just a replacement cost. It is a car that did not charge overnight, and on a commercial site it is a bay out of service until someone can attend.
Where It Is Not Really Optional
Some sites fall squarely inside Regulation 443.4 rather than the risk assessment route.
Apartment blocks and commercial buildings usually carry a safety service on the same supply: fire alarms, emergency lighting, lifts. Once a surge could interrupt one of those, protection stops being a cost question.
Sites with a lot of charge points sit in the same place for a different reason. The financial loss test is easy to meet when a single event could take out fifteen units at once.
Anything with a run of external cable is more exposed than an internal one. Car parks, gated compounds and depots pick up more from the network than a garage wall does.
How We Handle It
We look at surge protection during the electrical survey, before anything is quoted, because it changes what goes in the consumer unit.
If Regulation 443.4 applies, we fit an SPD and it appears on your certificate. If the risk assessment supports leaving it out, we say so and record the reasoning, so you are not left wondering later whether it was skipped or decided.
Either way it is a decision somebody made on purpose and wrote down, which is the part that matters if you are ever asked.
Who asks is usually the manufacturer, and the reason sits in the warranty rather than the regulations. No charger warranty we have read says that a missing SPD voids your cover, and anyone who tells you otherwise is stretching it. What myenergi’s terms say, and the wording is fairly standard across the industry, is that they will not cover a fault caused by an installation carried out “not in accordance with the Product Installation Manual and local codes and relevant regulations and any applicable legal requirements and industry standards”. A surge that kills a charger on an installation which should have had protection and did not is precisely the case that clause exists for.
So the thing that decides a warranty claim is not whether an SPD was fitted. It is whether the installation followed the regulations, and whether anyone can still show what was decided and why. That is the piece of paper we want you to have in a drawer. Most people never need it. The ones who do need it need it two years later, with a dead charger and a manufacturer asking who installed it and to what standard.
