Ohme [RCD activation]

Ohme build residual current protection into the chargepoint itself rather than relying entirely on the consumer unit, and they publish both what is inside and how to clear it. Their wording: the ePod has a Type A 30 milliamp and DC 6 milliamp RCD built in, the RCD in the unit is certified as an RCD-DD conforming to IEC 62955, and in the event of an RCD activation in the Ohme charger, the unit is reset by power cycling — switching the supply off, waiting five seconds, and switching on — or by unplugging and re-plugging the vehicle. That reset is explicitly sanctioned, which matters, because owner actions in this category are otherwise almost non-existent.

Ohme also publish a warning about what sits upstream, and it explains a class of problem that looks like a charger fault and is really an installation one. They recommend that any upstream RCD is at least Type A, because Type AC devices may saturate and fail to operate in the presence of smooth DC currents below 6 milliamps.

In plain terms, an older protective device in the consumer unit can be blinded by the kind of leakage a vehicle charger produces, which is why chargepoint installations have specific requirements and why an older consumer unit sometimes needs work before a charger goes in. That is worth mentioning to an electrician if you have a charger on an older installation. The judgement to make here is between once and repeatedly. Residual current protection can operate on a transient — water ingress in a plug after heavy rain, a damp cable end, a momentary leakage in the vehicle — and clear completely afterwards. One reset to test that is reasonable and Ohme sanction it. A device that keeps operating is detecting something real, and the sequence to follow is to stop resetting it and get the charger, the cable and the car looked at, in that order of accessibility rather than likelihood.

1. 1

   Unplug the vehicle and look at the plug and socket for water, grit or damage. Moisture in a connector is the commonest transient cause.

2. 2

   Re-plug the vehicle, which is one of Ohme’s two published resets and the less disruptive of them.

3. 3

   If that does not clear it, switch the supply off at the dedicated breaker, wait five seconds, and switch it back on. Those are Ohme’s published numbers.

4. 4

   Watch what happens over the next few sessions. A single event that never returns was a transient; a pattern is not.

5. 5

   Do not keep resetting a device that keeps operating.

   Residual current protection exists to interrupt a leakage path through a person. A device that trips repeatedly is detecting something, and resetting past it removes the protection rather than the fault.
6. 6

   If it recurs, get the installation checked and mention the type of protective device upstream. Ohme recommend at least Type A because Type AC may fail to operate in the presence of small smooth DC currents.