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

 

[redfox88]

Yes it doesn't help the meter has been moved and mounted on the board covering the cutout. Might find the meter has been bypassed inside the wall

It wouldn’t surprise me if it had ugggh all I can do is laugh in these situations. And also hope the house is still standing when we wake up ….

 

[Lucien Nunes]

I expect the OP gets the message about the urgency of the situation, but to anyone reading this in the future who is dithering about what to do, perhaps because the symptoms are not as clearcut the OP's overheating wiring, don't ignore suspected broken CNE (combined neutral/earth) connections.

This type of fault is rare but it is dangerous. Even when the load is light and none of the CPCs are showing signs of distress, the risk is still present of everything becoming live when some small thing that might be maintaining the earth continuity breaks contact. A good equipotential bonding setup reduces the risk of shock if that happens, but the fortuitous earth path might well be that bonding itself, so if it fails there is no protection left against severe shock.

Things I wish we knew before buying a house…

Don't beat yourself up, it may well be nothing to do with your house or its wiring. It could be a cable under the road that was grazed by a digger bucket in 1973 and has been slowly corroding since, or a very unlucky fracture at an overhead line tap that happens to move more than it should in the wind. But until properly diagnosed on the spot we can't say with any more certainty.

 

[redfox88]

Thanks all… hopefully get it all resolved soon.

 

[redfox88]

Just a wee update for ye

Networks came out. They couldn’t open up the wall. Said I was to do it but they will request permission from their supervisor to do this tomorrow.

As a result they couldn’t do all of their tests. However initially, the one of the live cables into the meter was damaged so needs replacing, neutral at meter was good but they’re not ruling out any damage of cables behind the wall.

Although they believe it’s unlikely a fault on their end…

Will see when they return tomorrow

We did another test today to find that when EV charger runs, we get 4-5 amps on the earth cable.

EV charger is disconnected now until source of issue is found

 

[redfox88]

Got the phone call this morning to say that they won’t do the opening up works and for me to start it, and they’d be here in a couple hours. They can kill the power if needed, if it’s getting dodgy.

Got most cut out to find a few nice surprises. Stopped when I knocked off the main fuse slightly and everything started sizzling

 

[littlespark]

I hope that red and black aren’t connected to anything.

I can see you having to make a much bigger hole than that.


Keep us updated, this one is really interesting.

 

[redfox88]

They’ve found problem with the neutral and are now stripping everything out and replacing everything their side.

Are the red and black cables on my side of the supply?

 

[LewisM]

How dense can you be to do that to a fuse and electricity meter

 

[littlespark]

The photographs aren’t clear enough to show how the old red and black are connected.

I’d be very surprised and somewhat shocked if they’re floating about live there.

Ask the guys doing the fix how bad it is….. we can explain any technical words they might use.

 

[timhoward]

Are the red and black cables on my side of the supply?

I'm fairly certain that they won't reconnect until they have checked as far as the meter connections, and in the course of doing this it should become clear what is going on.

 

[redfox88]

New fuse and meter supplied and readings they’re getting all good.
Their only comment was on the earth cable going from our unit into theirs, that it was too small but not major. Something to fix whenever electrician is out again

 

[Lucien Nunes]

Good stuff. So that leaves the question of whether any of your wiring was damaged by the diverted neutral current. What were the original symptoms exactly?

 

[redfox88]

That will be the next step yes. Initial assessment only shows damage to one particular outlet feeding one particular gas boiler appliance.
That appliance should have been earth bonded but it wasn’t. Perhaps why it was the victim or some other strange reason.
Will get that bonded, earth swapped at the meter and maybe a full survey of the inner set up. Electrician wants to rewire the board too and feed 6mm cable into the kitchen as everything bar the oven seems to be running off 1.5mm. Not sure if that’s from previous diy rewire or if it’s original cable.

The main thing is that this major issue is solved now. Takes the pressure off a little and can sleep a little better.

Any tips for what I can and can’t do to repair around where they’ve installed the new equipment?
The backer board is hideous and there’s still gaping holes around it

P.S thanks to everyone’s input on this thread. Ye saved me an absolute headache

 

[littlespark]

Would have liked a service isolator fitted to make it easy to change that board in future.

 

[LastManOnline]

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

Completely in agreement with all previous comments regarding DNO,s neutral.Its pretty certain that this house still has metallic services which are giving an excellent return path via the neighbours bonding.