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.

 

[James]

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.'

Always nice to read roughly what I was thinking,
but laid out in a form that can be understood by anyone. You have a fantastic way of explaining things.

 

[freddo]

I want to hear what the DNO say when they see the meter and cutout in that conditon!

 

[snowhead]

I want to hear what the DNO say when they see the meter and cutout in that conditon!

They'll say that they want it uncovered but that they won't touch it and untill the fault is located I doubt they will want anyone else cutting plasterboard, or whatever it is, away when the faulty / loose cable / damaged cutout may be behind there.
I would think they, the DNO (Networks) will want to cut off the supply outside, whether it be overhead or underground before anyone touches it.

 

[redfox88]

Sounds like we’ve a big of a nightmare on our hands…
Things I wish we knew before buying a house…the list is getting longer. This one definitely tops it

 

[freddo]

They'll say that they want it uncovered but that they won't touch it and untill the fault is located I doubt they will want anyone else cutting plasterboard, or whatever it is, away when the faulty / loose cable / damaged cutout may be behind there.
I would think they, the DNO (Networks) will want to cut off the supply outside, whether it be overhead or underground before anyone touches it.

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

 

[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.

 

[Lucien Nunes]

That appliance should have been earth bonded but it wasn’t. Perhaps why it was the victim or some other strange reason.

It's a likely contender if it is connected to metallic water or gas mains that were providing the best earth path after the CNE broke open. As you say, adequate main bonding would then have prevented damage to the wiring by diverting the current along a much heavier conductor. But... would you have discovered the problem in that case, or would the pipework have been left carrying the entire house load current for the foreseeable future?

Some of us here are not huge fans of TN-C-S, even in its PME guise.

 

[redfox88]

We also found that when we had the combi boiler installed early last year and new pipework done to meet spec, that the gas engineer never did any earth bonding on those pipes, nor did they say anything about needing to do it.
We also don't believe gas is earth bonded at the mains, despite certs from electricians, including more recently the EV install cert, claiming it is.

Strangely enough, networks called again today to upgrade the meter they installed yesterday to a new smart meter.

Recommendation again is to attach more sufficient earth cable from us to them, but also replace the black and red mains cables, the luxury for which will cost €160 for them to call out while that work is being carried out...I think that's what I read from the conversation any way. But he said the red and black were large enough for this not to be done immediately, although its near top of the list now with everything that's happened recently

 

[Lucien Nunes]

Under the current regs, when all relevant circuits are RCD protected, the requirements and necessity of supplementary bonding e.g. around the boiler are largely eliminated. But where there are extraneous metallic service pipes, which it seems you might have, main bonding is mandatory and all the more so with TN-C-S supplies.

 

[plugsandsparks]

Not withstanding what was a dangerous installation regardless of the EV charger, am left wondering why the EV charger did not detect an open PEN and shut down or at least there should have been a rod for the EV charger.......... think the OP would do well to get an electrician to go through the install with a fine tooth comb

 

[Lucien Nunes]

From the charger's point of view, it wasn't open-circuit. There was still continuity, just via the wrong conductors. There would have been extra voltage drop on account of their smaller CSA but perhaps not enough to signal an abnormal condition

 

[Lucien Nunes]

Deleted... duplicate post

 

[plugsandsparks]

Suppose it depends how it has been implemented in the EV charger. With what the OP was saying about hot earth cables around the property, i would expect to see unusual voltages and currents as measured at the EV charger, The Zappi for example has that many reference points built in to the charger that it has occasion shut down when there was no PEN issue, lol - Still think its one to note

 

[Risteard]

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

The EV chargepoint shouldn't have been installed if the main protective conductor (neutralising link) was undersized. This should have been rectified first.

 

[Risteard]

Not withstanding what was a dangerous installation regardless of the EV charger, am left wondering why the EV charger did not detect an open PEN and shut down or at least there should have been a rod for the EV charger.......... think the OP would do well to get an electrician to go through the install with a fine tooth comb

PEN fault disconnection is not a requirement of I.S. 10101.

 

[davesparks]

Not withstanding what was a dangerous installation regardless of the EV charger, am left wondering why the EV charger did not detect an open PEN and shut down or at least there should have been a rod for the EV charger.......... think the OP would do well to get an electrician to go through the install with a fine tooth comb

There are differences between Irish and UK regs and as far as I know an earth electrode is required for the whole installation under Irish regulations when a TNCS supply is used.

 

[Risteard]

There are differences between Irish and UK regs and as far as I know an earth electrode is required for the whole installation under Irish regulations when a TNCS supply is used.

Correct. Every installation requires an Earth electrode.

 

[plugsandsparks]

Just had a browse on some chargers and the Tesla for example would have seen the rod and concluded no problem, assuming Earth fault detection was enabled for that install. I am pretty sure a Zappi would have gone nuts either with under-voltage L-N or N-E v Diff

Interesting though how to melt your house cables,

 

[redfox88]

UPDATE: came home from a couple nights away to no power in the house. The main RCD had tripped.
I traced issue to blow 3A fuse in the switched fuse spur powering the gas boiler. I replaced the 3A fuse but the boiler didn't power.
Further inspection inside the boiler should me that the small fuse inside the boiler had blown.
And further inspection again showed me cabled inside the boiler had been overheating. The loom connecting all the components was melting, and the cables connecting those components to the pub had been melting too. Absolutely no idea why. Power to boiler is sound and no issues anywhere else on the circuit except for the boiler.
Gas boiler installer and repair guy is calling to replace entire boiler as opposed to just components and wiring from the last time round.

 

[James]

It sounds like a possible fault with the supply N
this may be somewhere along the supply cable or even at the substation.
a call to your energy supplier emergency hotline is the best place to start.

 

[redfox88]

Again? Really? They've just installed (Jan '23) new fuse and meter joining in new L & N into the house

 

[baldelectrician]

The installer should have confirmed the Ze (external earth loop) with the rest of the property off and earths disconnected. The fact that was all boxed in means this was not done

As a matter of urgency get the main gas and water pipes bondedm this way stray earth currents are likely to go through the bonding and not your boiler wiring loom

I would also suggest you contact the car charger manufacturer and ask them to send someone to asess the situation

I also noticed the EV installer appears to have installed a Hager RCD inside an Eaton unit- not good

 

[RoryDickerson]

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

It's difficult to diagnose the exact cause of the fault without more information, but overheating and melting of the earth/ground wire in the cabling could indicate a short circuit or other electrical fault. The fact that other appliances in the house are also being impacted suggests that the issue may be related to the electrical system in the house rather than just the EV charger.
It's possible that the EV charger is drawing more power than the electrical system is designed to handle, causing a voltage drop and increased resistance in the wiring. This could cause the earth/ground wire to overheat and melt, and could also impact other appliances in the house.
It's important that the electrician continues to investigate the issue and performs comprehensive testing to identify the root cause of the problem. They may need to check the wiring and connections throughout the electrical system to ensure that they are properly sized and installed, and may need to perform load calculations to ensure that the system can safely handle the additional load from the EV charger.
In the meantime, it's recommended that you stop using the EV charger until the issue is resolved to avoid further damage to the electrical system and appliances in the house.

 

[brianmoooore]

Another Bot alert!
..... ......

 

[Risteard]

I also noticed the EV installer appears to have installed a Hager RCD inside an Eaton unit- not good

There is no Annex Zb derogation within I.S. EN 61439 so no conditional short-circuit rating for type tested units etc. so there is no prohibition on that. Of course this is assuming that it had been connected correctly e.g. supplied with tri-rated panel flex outer something similar.