EV charger tripping the electrics

What it usually means

This is the one page in this category where the answer is not to investigate further. A home chargepoint is required to carry protection that most household circuits do not, and understanding what those devices watch for explains why repeatedly resetting one is the wrong response rather than merely an unproductive one.

Three separate protections are usually in play. The first is residual current protection, which watches for current leaving the circuit by a route other than the one it came back on — through water, through insulation, through a person. The second is direct-current detection, because a car's onboard charger can leak a small direct current that a conventional residual current device is not able to see and can even be blinded by; UK wiring rules require this to be covered, and many units build in detection at around six milliamps. The third is the one people have never heard of and is the reason for the strongest wording here: protection against loss of the combined neutral and earth conductor in the supply.

That last one is worth explaining plainly. On most British streets the earth for a house is derived from the supply neutral. If that conductor fails somewhere in the network — and it does, particularly on older cables — the earthed metalwork in the house can rise to a dangerous voltage relative to the ground. Indoors that is bad enough. On a driveway, where somebody is standing on wet ground holding a metal car connected to that earth, it is lethal. Chargepoint installations are therefore required to detect the condition and disconnect, or to be earthed independently, and a unit reporting this has done something no ordinary appliance can do.

So the diagnosis worth doing is observational, and it can be done entirely from where you stand. Does it trip the moment you plug in, or partway into a charge? Does it happen with one car and not another, if you have access to two? Does it happen in the rain? Which device moves — the one inside the chargepoint, or a breaker in the consumer unit? Is it the same car that trips a public charger too? These distinctions matter to whoever attends: a fault that only appears in wet weather points at water ingress in an enclosure or a cable gland, a fault that appears at the same point in every charge points at the vehicle's onboard charger, and a fault that comes and goes without the car connected points at the supply.

What no observation can justify is putting the circuit back on repeatedly to see what happens, or asking anybody to make the protection less sensitive. These devices are installed under specific requirements for driveway charging, and the fault they most consequentially detect is one where the warning sign and the injury are the same event.