Issues with installation of EV Charger

[baseborn]

Hi - i'm very much a layman here but hoping someone can shine a bit of light on this for me as i feel like i'm getting messed about a bit - but not sure by whom.

House was built in 2020 by a local building firm. We have the DEIC which states it has TNS earthing, and the means of earthing as 'Distributors Facility'. There is nothing in the 'where an earth electrode is used' section. Octopus have been out to install an EV charger today but are adamant it's not a TNS, but instead is a TT earthing arrangement. The electricians who were involved in the building of the property weren't that helpful when i called one of the owners (who signed the DEIC) as he said he can't remember how it was set up. There is a green/yellow wire attached to the pipe that runs down the wall from the meter, but it's in a raised garden bed and goes pretty deep underground - we can't find an earth rod anywhere obvious.

We've called the DNO connections team as advised by the installer and they've emailed back to say they will be in touch shortly to arrange to 'provide a connection to earth'. I've emailed back asking for their records regarding the connection and the manner of earthing.

The installer said the measurements indicate that the property is earthed, but because they don't know how, they won't connect the charger. He referred to the supply parameters which show Z as 0.11, and he says he measured 0.15, but when he tested the charger it showed 0.53 so he doesn't understand how the electrician got the measurements he got. None of this means much to me!

I suspect the installer is wrong and that it is a TNS system as everything else seems to look that way - other than waiting for the DNO to get back to me and hopefully confirm the setup so i can go back to Octopus to complain, is there anything I can do to speed this up? I've asked the electricians to come back out to look at the unit but not sure if when they will come - and i'd rather not incur more expense.

Appreciate any help I can get. Thank you!

 

[PS Electrics]

Hi - i'm very much a layman here but hoping someone can shine a bit of light on this for me as i feel like i'm getting messed about a bit - but not sure by whom.

House was built in 2020 by a local building firm. We have the DEIC which states it has TNS earthing, and the means of earthing as 'Distributors Facility'. There is nothing in the 'where an earth electrode is used' section. Octopus have been out to install an EV charger today but are adamant it's not a TNS, but instead is a TT earthing arrangement. The electricians who were involved in the building of the property weren't that helpful when i called one of the owners (who signed the DEIC) as he said he can't remember how it was set up. There is a green/yellow wire attached to the pipe that runs down the wall from the meter, but it's in a raised garden bed and goes pretty deep underground - we can't find an earth rod anywhere obvious.

We've called the DPO connections team as advised by the installer and they've emailed back to say they will be in touch shortly to arrange to 'provide a connection to earth'. I've emailed back asking for their records regarding the connection and the manner of earthing.

The installer said the measurements indicate that the property is earthed, but because they don't know how, they won't connect the charger. He referred to the supply parameters which show Z as 0.11, and he says he measured 0.15, but when he tested the charger it showed 0.53 so he doesn't understand how the electrician got the measurements he got. None of this means much to me!

I suspect the installer is wrong and that it is a TNS system as everything else seems to look that way - other than waiting for the DPO to get back to me and hopefully confirm the setup so i can go back to Octopus to complain, is there anything I can do to speed this up? I've asked the electricians to come back out to look at the unit but not sure if when they will come - and i'd rather not incur more expense.

Appreciate any help I can get. Thank you!

You have an Electrical Installation Certificate that states TNS and the test results are consistent with it being TNS

TNS would be a max Ze of 0.8 TNCS would be a max Ze of 0.35, TT will generally be a lot higher than those values.

Octopus must have some reason to believe that it is TT and I assume it is what they have observed visually. Your DNO should be able to advise you of the Earthing arrangements you have.

May be a picture of your service head would help.

 

[baseborn]

Thank you - I’ve uploaded some photos

 

[baseborn]

 

[baseborn]

I’ve uploaded 3 pics but 2 are awaiting mod approval. Hopefully they show up soon!

 

[PS Electrics]

I’ve uploaded 3 pics but 2 are awaiting mod approval. Hopefully they show up soon

Looks like we can rule out TNS!

Cannot rule out TNCS without seeing more of that service head, those other pictures haven't come through. The Earth cable could then be a Bonding conductor for Water or Gas that was easier to route externally.

Certainly can see why Octopus think it is TT and since they have seen this I am going to guess there is no Earth connection at the top of that Service Head which would make it TNCS.

Can't believe they left those scraps there and the service head looks like it is not properly fixed on one side.

If it isn't TNCS then we must assume it is TT but the dilemma Octopus have is the readings don't align to TT and they cannot find the Earth Rod so I have to agree the earthing system is not proven.

There are other ways to provide TT other than Earth Rods though, like buried Earth mats or the use of Structural Steelwork these can result in lower readings than typically that which earth rods can provide.

This will be sorted out and I totally understand your frustration but can see why Octopus have not gone ahead with the install with what has been shown.

 

[baseborn]

Thank you - trying photos again

 

[westward10]

Is that an offcut (the circled part)?

 

[baseborn]

Is that an offcut (the circled part)?View attachment 123197

Yes - I’ve added another photo

 

[westward10]

Is it possible to look at one of the neighbours' electrics?

 

[baseborn]

Is it possible to look at one of the neighbours' electrics?

It’s a one off new build, they literally built one house on a plot that’s not been developed before

 

[westward10]

It is impossible to say for certain the earthing system without being there to investigate.
I'm wondering if that earth you moved was the earth from the head to the terminal block, looks the correct length and something has been used through the two screw holes.

 

[baseborn]

All that additional cabling is from octopus today - this was the box last month.

 

[PS Electrics]

Oh I see what you mean now - the two holes on the front of the head and then running to where the other green/yellow cables are? Would that potentially be the earth? What format would that take as the EIC says TNS?

TNCS

That bit of cable would have been the link as Westward said

It is stripped both ends and is about the right length as he pointed out.

DNO will confirm if it is TNCS then they will need to reconnect the Earthing.

Then that Earth cable running down the pipe is likely Gas or Water Bonding run externally.

 

[PS Electrics]

View attachment 123205
All that additional cabling is from octopus today - this was the box last month.

Plot Thickens


Looks like Octopus attempted to make it TNCS!!

 

[baseborn]

Plot Thickens


Looks like Octopus attempted to make it TNCS!!

So we still think it’s TT then?

 

[baseborn]

And that this is completely wrong

 

[baseborn]

Electrician is adamant it’s earthed by the DNO btw

 

[westward10]

Not necessarily it could be TN-S.

 

[PS Electrics]

So we still think it’s TT then?

Trying to play detective

Normally the earth cable is connected to the sheath of the service cable when TNS and is normally done just below where it enters the head. That Earth cable might well still attach to the sheath at some other point though, so like westward said it could still be TNS.

It looks TT so can understand why Octopus thought that but you don't normally get such low Ze readings like that on TT.

We are assuming the testing was done correctly and that cable was disconnected when testing to rule out parallel paths.

Add to that the EIC says it is TNS.

I would see what the DNO say the earthing arrangement is hopefully that clarifies it.

If the DNO says it is TNS then armed with that you can tell Octopus that and then the DNO are responsible for the Earthing Arrangements and Octopus should between them and the DNO sort it out.

 

[baseborn]

Thanks both so much. I suspect Octopus have made a mess of it as the guy didn’t fill me with much confidence and everything else says TNS. I will investigate further with the DNO and report back

 

[brianmoooore]

Normally the earth cable is connected to the sheath of the service cable when TNS and is normally done just below where it enters the head.

Not on new stuff. Two of my TNS supplies have split concentric service cables coming up from underground ducts, into service heads exactly like those, and the earth connection is to the side of those service blocks, exactly like it would be for TNC-S. There's a link inside the head that's fitted for TNC-S, but left out for TNS.

 

[baseborn]

DNO says their records don’t state what earthing they provided - which is very helpful! Waiting for them to book in a survey and will try push octopus for a revisit by a different engineer in the meantime. What a faff!

 

[PS Electrics]

DNO says their records don’t state what earthing they provided - which is very helpful! Waiting for them to book in a survey and will try push octopus for a revisit by a different engineer in the meantime. What a faff!

Well it is progress at least.

With so much conflicting info getting the DNO to survey is the right thing. You will get a definitive answer on the earthing arrangements there which will allow you to move forward.

Something strange is going on because Octopus obviously at some point tried to make it TNCS and for some reason started it and then stopped it, they may have actually done it and then took it out, I guess we will never know!

Good luck and please report back it is always great to find out what actually happened as it helps to inform others.