Thoughts on this earthing at cut out.....

Gavin John Hyde · Apr 15, 2019

On a job this evening just taking a look around and meeting customer as wants downstairs rewired.
Only collecting keys before i go back and do a few tests and quote fully.
Appears at sometime to have been TNS but changed to PME?
Instead of earth and Neutral joining in the cut out. They are joined in a Henley.
Is this permissable?
First thought was no. But more I think about it. What difference does it make so long as they join - be it in cutout or henley a few inches later?
Thoughts?

Images show earthing in henley going behind board to CU.
Old bonding strap fixed to outer sheath!!
Cut out without earth going in the side. On closer examination it appears there is a small hole, presumably for the earthing but has lack of access.

[ElectriciansForums.net] Thoughts on this earthing at cut out.....

TJ Anderson · Apr 15, 2019

That looks like a non-DNO TNCS. Also that BS951 clamp should have never been used for TNS earthing conductor, crushing the cable.

Wilko · Apr 15, 2019

It does look a bit homemade ...

Dustydazzler · Apr 15, 2019

Diy pme ?

Gavin John Hyde · Apr 15, 2019

TJ Anderson said:
That looks like a non DNO TNCS. Also that BS951 clamp should never be used for TNS earthing conductor, crushing the cable.

Agree on the BS951 clamp used for TNS. it certainly looks like a improvised PME set up. but is it compliant? I will test the readings later in week when I go back. might have to get WPD out to give once over.

TJ Anderson · Apr 15, 2019

Thing is you won't really know if it is. You will have a low impedance loop L-N & L-E, most likely less than 0.35 ohms Ze, but is it really TNCS? Could have a look in neighbours house if poss, see if they have a TNCS cutout. Should definitely get DNO out to look at that.

Wilko · Apr 15, 2019

I've sent in special pics like this to local DNO a few times and they will do a free "safety check" if they feel it's warranted.

lemonkettaz · Apr 15, 2019

If it’s TNS will be different readings L-E and L-N being separate conductors whereras TNCS would give exact same readings as it’s the same conductor ?

Gavin John Hyde · Apr 15, 2019

Wilko said:
I've sent in special pics like this to local DNO a few times and they will do a free "safety check" if they feel it's warranted.

Just got off phone with customer, he is going to contact WPD the local DNO and get them to send an engineer out to check it and give once over.

TJ Anderson · Apr 15, 2019

lemonkettaz said:
If it’s TNS will be different readings L-E and L-N being separate conductors whereras TNCS would give exact same readings as it’s the same conductor ?

Yeah, you get same readings as they are supplied by same conductor. The issue is, this is using the dedicated neutral of the old TNS as a PEN conductor when it may not actually be one...

DefyG · Apr 15, 2019

Got the DNO out on a job last year with too high Ze reading for a TNS and the remedy? - They did exactly as shown by Gavin's pics!
So not necessarily a DIY PME!

Which One’s Live? · Apr 15, 2019

Is it a secondary cutout? That's where I've generally seen this done, especially when they are a few neutrals to combine, so the cutout is effectively extended using a block. But even then, I've not seen an earth thrown in there ad-hoc.

Anyway, there's only one neutral so I'm probably wrong.

Gavin John Hyde · Apr 15, 2019

Which One’s Live? said:
Is it a secondary cutout? That's where I've generally seen this done, especially when they are a few neutrals to combine, so the cutout is effectively extended using a block. But even then, I've not seen an earth thrown in there ad-hoc.

Anyway, there's only one neutral so I'm probably wrong.

No secondary cutout. It comes in from outside. To immediate left is the front door.

DefyG · Apr 16, 2019

Ditto, primary cutout.

The Ghost · Apr 16, 2019

Of course in the regs the use of neutral and earth combined is not permitted within the installation. But technically I guess it is not within the installation it is prior to the meter and within the responsibility of the DNO. I do know of electricians that do not hesitate to do their own PME like this so yes it may be a diy. Update us @Gavin John Hyde when they look.