tn-s. Ze 27ohms

[17thman]

just tested neighbours Ze because he has just had an engineer come to deliver a cooker and he got 27ohms at the socket. main eathing conductor fitted snug in met and appears solid at metall supply sheath.

Told him to call DNO. What could be possible cause?

Thanks

 

[Spark123]

More than likely something has happened to the upstream DNO cable, could have been damaged, dodgy termination or just rotted through.

 

[17thman]

I assume, depending where the fault is it could effect other properties. I have a tns, will check it after dinner!

 

[RF Lighting]

Don't forget to disconnect your bonding when you test for Ze

 

[17thman]

i see there has been another post on this yesterday so sorry for the repetition. Someone needs to speak wise words to me.

Yer man over the road has had an operator turn up from central networks only to say "yes, these houses were not supplied with any earth". You'll need a pme and that will be £150.00. goodbye"

Now hold a minute. He has a tns supply and an earth clamped to the metal sheath. Why is the DNO therefore not responsible for maintaining this. They have just walked away.

So, could it be a subterranean tt(mentioned in previous post) and some previous occupant has removed the spike or there never was one and just clamped an earth (it is not sweated)?

Am i missing something and the DNo have no resposibility to maintain a tn-s earth.

On a few occassions recently, when i have enquired to central networks about fuse types and supply, their mantra is "we just don't have that information, we just don't.

who can calm me down?

 

[RF Lighting]

If they have provided an earth then it is their duty to maintain it.

Proving they provided an earth in the first place might be a bit more difficult.

Round here they do not seem to question it. As long as it is one of their clamps (i.e. not a shiny new BS951) they will sort it for free.

They also only charge £75 for a PME connection if there is no existing earth terminal.

 

[oharaf]

HI Rob, interesting that one.

Here the fella didn't bat an eye at the BS951, I have also been told that PME is £150!!!!

And we are what - 2 miles apart?!!

Suprise they make it up as they go along!!!!!

 

[17thman]

yes RF, this is where central networks can play hard ball. They know that it would be very difficult indeed to prove they did not supply an earth connection. He has got detached outbuildings with water supply So there may be some work in it for me.

 

[RF Lighting]

HI Rob, interesting that one.

Here the fella didn't bat an eye at the BS951, I have also been told that PME is £150!!!!

And we are what - 2 miles apart?!!

Suprise they make it up as they go along!!!!!

Yep, that is odd.

We will both go through to the same call centre at YEDL / NEDL headquaters in Newcastle.

I was given the price for a PME upgrade about 4 weeks ago whilst arguing about who has to pay for a failed TN-S.

I won

 

[securespark]

The REC may be right. Many so-called TN-S supplies are in fact subterranean TT supplies with the sheath connected to nothing. Then folk come along later and slap a 951 on it, thinking that'll do the trick.

It is becoming increasingly common for me to report high Ze's to UU and for them to come long, find a 951 and wash their hands of it. Usually, if it is a genuine TN-S and a 951 has been stuck on, I can persuade the engineer to fix it. But if it is a TT supply, then chances are the sheath is not connected underground. In which case it's a rod or PME.

 

[Spark123]

Wonder how they stand should a fault make their cable sheath live and you were to get a shock

 

[17thman]

sorry to ressurect the post lads, securespark or anybody, is there a way to identify whether it was originally a tns or subbterranean tt?

RF, did you have a line of arguement, customer must part with cash before engineer shows

 

[RF Lighting]

There is no way to tell for certain, but if there is an earth soldered onto the lead sheath of the incommer then chances are pretty high that its always been TN-S

Also the age of the earth clamp will give you a fair idea. The old two part cast iron clamp, and old style BS951 clamps are a good indicator.

People were not as concerned with earthing back in the day, so were less likely to try and connect it them selves.

Also the area will play a part. Round here it is very very rare to see a subterranian TT supply.

In the local area where I live, I can't remember working on a TT supply ever, but 5 or so miles away that is all you will find.

With my last high Ze, the DNO tried it on on the phone. I'm not sure if it's a deliberate ploy, or just the woman in the call centre who didn't really understand what I was telling her.

She kept saying that is is the customers responsibility to provide an earth, but they could provide a PME terminal for £75.

I eventually got through to her that it was a failed existing TN-S connection, and after 15 mins on the phone, they sent the emergency chap to have a look.

He put his tester onto the MET, and said "it's fine mate, look, I've got 0.34Ω"

I asked him to disconnect the bonding and try it again

Anyway, next morning they turned up, swapped the 30A cast iron cutout for a nice new BS1361 100A head and provided a PME terminal, all free of charge

 

[17thman]

cheers RF. they have got the old 2 part clamp and i told them to phone the dno today and say that. Answer was "well that could have been put on recently by anybody" No tt's in this part of Birmingham from experience. It is a deliberate ploy. pme pme pme is what you want! we have no records at all of your earthing arrangement or fuse type!!..

I will take this matter into my own hands and enjoy the dialogue.

0.34 Through the bonding? thats good

 

[plugwash]

The REC may be right. Many so-called TN-S supplies are in fact subterranean TT supplies with the sheath connected to nothing.

Isn't that illegal? doesn't the law require the electricty companies to maintain an earthed metal protective layer arround thier cables?