EV charger causing ground overheating

[redfox88]

Had an EV charger installed in July last year. It’s wired directly off the mains.

Since end of November anytime I plug the car in to charge, the earth/ground wire in the cabling in other appliances in the house is overheating and melting components of the appliance until the main RCD trips.

Has anyone ever seen or heard this happening before and what could be happening?
Even appliances isolated by switch fuses, when off are getting impacted. It’s concerning.

Electrician has been doing tests but is not quite sure what could be causing the fault

 

[James]

Sounds like a fault with the incoming neutral
it is disappointing that the electrician is struggling to find the fault.

 

[westward10]

Can you show a picture of your main electrical service head.

 

[westward10]

Sounds like a fault with the incoming neutral
it is disappointing that the electrician is struggling to find the fault.

Yep my first thought.

 

[redfox88]

Can you show a picture of your main electrical service head.

This probably won’t help much. Previous owner seems to have built out the wall burying the cables from the meter behind it. Been waiting a year for networks to come out to assess and upgrade this part of it

 

[Lucien Nunes]

It sounds like your supply cable has a combined neutral/earth connection that has become disconnected upstream within the DNO's equipment, possibly in the service head but also possibly in the road. The load current, of which the car charging is the heaviest, is flowing from its own circuit neutral to the point at which neutral and earth combine in the DNO's service terminal equipment, then back down fortuitous earth paths in various other circuits that are not intended to carry such large currents.

If this is actually the case, there is a likelihood of serious damage, fire and shock, and it probably isn't the fault of your installation. The DNO will attend as an emergency as there is a risk to life from all earthed equipment suddenly becoming live, if the fortuitous earths give out. Unfortunately, this particular scenario doesn't normally cause RCDs to trip as they cannot 'see' the problem which is upstream of them.

Don't use heavy loads, get it sorted immediately. I too am surprised by the response of the electrician. I would expect to be able to diagnose this conclusively within about 30 seconds. Unless there is some other completely bizarre explanation like trolls under your floor using arc welders.

The meter and head absolutely should not be boxed in like that, and the DNO would insist that the obstruction be removed in order to inspect. The problem might be right there behind the 'wall.'

 

[westward10]

As above two us immediately thought a supply neutral problem (I suspect your earthing system is TN-C-S), any competent electrician should quickly assume this.

 

[nicebutdim]

Going to tag @LastManOnline in this as I'm certain he'll be interested in learning more about it.

 

[redfox88]

I should mention, we didn’t realise the EV charger was the culprit until today.
And what ye are saying makes sense because initially car was charging at 1.6kw but when fast setting was switched on and power consumption was upped to 6kw, that’s when we noted the issue.

So does this need to be confirmed by electrician first or should this all sit with the electricity supplier to test, confirm and fix?

 

[Lucien Nunes]

two us immediately thought a supply neutral problem

I think we should be rigorous and say specifically it is most likely a 'combined neutral / earth problem' as a problem with just a plain old neutral would simply cause the lights to go out and not create nasty currents in the earthing system.

There is a less-likely alternative scenario that doesn't necessarily involve the DNO, and that is a multiple fault; the neutral is broken or high-resistance upstream of the RCD, and there is also a neutral-earth short(s) on one or more non-RCD-protected circuits. We can't decide whether this is likely without seeing the arrangement of circuits and protective devices. Or of course, the neutral upstream of the board shorted to earth, which is actually conceivable with that daft arrangement of the tails being boxed in.

Any electrician who knows what she / he is doing, should be able to say 'yup, this is a DNO problem.' or not. It probably is, but if you call them out and it isn't, I don't know what the charges are. Somebody here will, and probably also know how to go about claiming for damage to your wiring through overheating, if their supply is proven to be the culprit.