EV charger issue - Garo PME trips

[ElectricallyRandom]

Hi. Not sure if it's the right place to ask, so won't be upset if it gets removed. Apologies if the terminology (PEN/PME/etc) is used inaccurately.


I had an EV charger installed in December on my detached garage by a local electrician. The charger is one that doesn't have a PEN fault detection device (Tesla), hence we agreed I'd get it separately (Search Results - Detail - https://www.garo.co.uk/product-details/All/G6EV40PME).


Armoured 10mm^2 cable (from main circuit board to garage - approximately 32 meters) has been used to the garage where a smaller consumer board and the PME fault device was fitted. From there there's around 4-5m of 4mm cable to the actual charger.


After awhile I've noticed that the PME fault device trips every now and again - always late in the evening or at night, although that's mostly when I charge. It is quite sporadic, although in reality probably happens every 5-6 charges, which can be annoying in the morning if I miss the message on the car's phone app.


Interestingly the Tesla charger integrates with my Home assistant, so I can see the voltage at the charger, which seems to significantly drop on some evenings/nights (expected under load?), although never below the PME device's 207-253V range.


I have raised this with the electrician several times and he's not sure why this is happening. Also everything seemed fine on the 2 occasions he's tested it - once after installing and later when I raised the problem with him. However the test was never done by him at the time when voltage significantly dropped.

I did measure the voltage myself once when the voltage seemed low, soon after the PME device tripped and I reset it. In the house - ~232V, in the garage's consumer unit - ~230V, meanwhile Tesla charger in Home Assistant reported approx 222V while charging.



Question - where would I go from here ? Is there anything obvious another electrician would perhaps notice.. ?

Some photos attached.

Thank you

 

[marconi]

It may still be just a faulty RCBO as others have mentioned. You could reasonably ask the electrician who did the work to contact GARO to obtain a replacement. Or you could contact GARO...

What is the first half of your postcode?

I have just sent a missive to GARO technical desk on this problem.

 

[ElectricallyRandom]

It may still be just a faulty RCBO as others have mentioned. You could reasonably ask the electrician who did the work to contact GARO to obtain a replacement. Or you could contact GARO...

What is the first half of your postcode?

I have just sent a missive to GARO technical desk on this problem.

SO22. I will give them a ring myself as I've bought thw Garo myself to be installed.

 

[marconi]

Just spoken on the phone with GARO technical desk. They will do the swap of the RCBO no problem. You need to take proof of purchase to the retailer/wholesaler and ask them to order a replacement RCBO - may even have one in stock. GARO do not deal direct with the public he said.

When wholesaler informs you that replacement has arrived you can collect it. You will have to pay for it until you return the original and get a credit. Or, one could remove the original and exchange for the replacement at the same time. Whatever happens the suspect RCBO has to be sent back to GARO for testing. Or something like this ;-)

The email I used was [email protected] (very helpful).

Please let us know the outcome because we all learn this way.

 

[marconi]

ElectricallyRandom: Don't be shy. Have you now resolved the problem?

 

[Risteard]

My guess is either a faulty Garo unit or a regular supply voltage fluctuation that is too short to be picked up by the sampling the car charger is doing hence you can't see it on the app.
Leaving a decent multi-meter connected on min and then max might prove the point, failing that a voltage data logger could be hired and connected for a few days.
Even if you prove that, getting the DNO to do something about it can take effort and endurance.

To be honest I don't highly rate the methodology used by the Garo Pen protection devices as they aren't guaranteed to detect an open PEN conductor in all circumstances (subject to what loads your neighbours are pulling at the time) and they can be triggered by supply issues (as you may be seeing).

If it were me I'd be seriously considering banging an earth rod in and changing the earthing arrangements in the garage, removing the need for the PEN protection device completely.

I don't want to cause additional concern but a couple of unrelated things jump out at me too:
-you may have a PV system on a shared RCD in the house CU. This is a no-no as there's no point the RCD tripping to save your life if the PV system continues to deliver power until it notices it should shut down.
-the RCD topology isn't ideal - I think there's three 30ma type A RCD's in series. A Type B would normally be fitted for an EV charger.

Also the EVSE must not be on a shared RCD which it is.