Random EV connector PEN tripping

[^woody^]

What can cause at PEN device to trip randomly?

The EV connector is wired to it's own CU, which is in turn split from a Henley block, so is on its own circuit.

The PEN device trips randomly, sometimes it can be weeks between, sometimes several times a week. It can trip when the EV is connected or not, charging or not, in wet weather or weeks of dry weather, warm or cold weather.

Anecdotally, it seems to trip over night - sometime between 11 and 7. And again anecdotally it seems to trip in batches - more frequent over a week or so, then OK for two-three weeks. But this is not definite.

The PEN device always resets OK after each time it trips and has never tripped on consecutive days.

In 10 months it's not got any worse or more frequent, just completely random.

Fitted Consumer Unit IP40 2 Pole Type A RCBO + PEN fault Detection + Surge Protection​

 

[baldykev]

Not an expert but fluctuation in power can cause this, Voltage to high or to low will trip the PEN
Is there any one else in your street who has this problem ?

 

[ericmark]

My worry is a poor connection on a PEN, in other words the unit is doing its job.

 

[Risteard]

As with @baldykev I suspect the supply voltage is going out of tolerance.

 

[plugwash]

As has been said, most PEN-fault detection devices actually detect out of spec voltages, the idea being that a PEN fault will cause such out of spec voltages. There are other types, such as ones that use an earth electrode to measure voltage between the PEN and real earth but these are more of a pain to install.

I would say next steps are.

1. A Ze test
2. Setting up a voltage monitor.

The results of these can the potentially be used to substantiate a complaint to the DNO.

 

[^woody^]

2. Setting up a voltage monitor.

Yes, the complete randomness of this problem made me suspect an incoming voltage issue - and perhaps this may explain the apparent occurrence at night .... perhaps when things are done to the grid?

This voltage monitor, is that a clamp meter? I have been looking and assumed it would need something that records the time of high and low voltage? Any recommendations for something at reasonable cost ie from Ali Express lol.

 

[^woody^]

My worry is a poor connection on a PEN, in other words the unit is doing its job.

There is nothing obvious, and I would suspect a loose connection to show up more frequently and predictably.

 

[^woody^]

Not an expert but fluctuation in power can cause this, Voltage to high or to low will trip the PEN
Is there any one else in your street who has this problem ?

I don't think there is another EV connector for 100's of metres away, and voltage supply does not crop up in the convo's with neighbours.

 

[ericmark]

My solar panels record any trips due to over/under voltage, so anyone with solar may have a record. A broken PEN OK it will detect it quickly, but a poor connection could go on for years without detection.

 

[flameport]

and perhaps this may explain the apparent occurrence at night .... perhaps when things are done to the grid?

Things are not 'done' to the grid or anything else specifically at night.
More likely is that the voltage overnight is exceeding the specified limits, as loading overnight will typically be much lower than in the day, and therefore the voltage will increase.

This needs further investigation, as excessively high voltages will cause damage to connected equipment.

 

[ericmark]

My house has a TN-C-S/TN-S supply, from DNO it is TN-C-S but if there is a power cut, from the inverter it is a TN-S. So I have a small earth rod, for when running on TN-S. This is common, so we end up with a PME system with as the name implies multiple earths.

So with a reasonably balanced 3 phase supply, the volts may vary more than they should, but it could well keep within limits with a broken or poor connection on the PEN and no one notice.

Only as we get high demands on one phase will the voltage go out of limits, even the DNO earth to true earth may not vary enough to be outside the limits. So as @flameport says, it needs further investigation, so have you reported fault to the DNO?