[Charger keeps tripping]what to check

A chargepoint that trips out and refuses to charge is often reporting something about the electricity coming into your house rather than about itself, and that is a distinction worth understanding before you reset it for the fourth evening running. UK wiring regulations require a chargepoint on the common type of domestic supply to protect against the loss of the combined protective earth and neutral conductor: BS 7671 regulation 722.411.4.1 offers a choice between an earth electrode and a device that detects the fault and disconnects, and the IET explain why it matters — if that conductor breaks, the metal body of the car can become live. Most manufacturers meet the requirement by building open-PEN detection into the unit rather than by installing an earth rod. Myenergi describe it as built-in protection against the loss of the protective neutral and earth conductor as required by BS 7671:2018 Amendment 1:2020, say in their installation manual that because it is built in there is no need to install an earth electrode, and describe what happens when it operates: the charger becomes completely isolated from the input supply, so that all conductors present at the output socket or cable, including protective earth and control signals, will be safe, removing any risk of potential electric shock. The commonest form of the detection is the one written into the regulation as option (iv): disconnect within five seconds if the voltage at the charging point, line to neutral, goes above 253 volts or below 207 volts.

Ohme publish exactly those numbers for their units, citing that clause, and they are useful because they explain the pattern. Their units disconnect the vehicle if the voltage is greater than 253 volts or less than 207 volts, the same window produces what their app records as overvoltage or undervoltage errors, and on the Home Pro the unit deliberately waits five minutes after the voltage recovers before reconnecting the car, so that a supply hovering around the threshold does not switch the vehicle on and off repeatedly. That is a measurement of your supply, not of your charger. Myenergi's zappi works to a slightly different published figure — more than twelve per cent from 230 volts for five seconds, resetting itself once the supply is back within ten per cent — but the principle is the same. Ohme's remedy is the most useful thing published in this category, because it sends you somewhere most owners would never think to call: your distribution network operator can test the voltage levels at your home and help adjust them, they should monitor over several days rather than take one reading because voltage fluctuates through the day and night, and once confirmed the operator will resolve it at your local substation.

Ohme even say to keep using the charger normally during the monitoring period. The network operators themselves publish the same route from their side: UK Power Networks say a charger that trips on voltage is a safety feature working, that you may need to switch it off and on at the isolator, that you should first have your installer or an electrician check your own equipment, and that if the problem persists they will send an engineer and, if necessary, fit a recording device for two weeks. The IET add a cause that is neither the network nor the charger: voltage drop along a long or undersized cable within your own installation can pull the voltage at the charging point below 207 volts under full load while the supply at the meter is fine, and that is an installer's measurement to make. So there are two quite different situations. If the trip is at the charger and clears on a reset, note when it happens and check the app for a voltage record. If the trip is the RCD or breaker in your consumer unit, and it happens more than once, stop resetting it and get an electrician.