TT off water main or tncs with no earth (Victorian house city centre)

[James Kinrosd]

Hi guys came across this today, Ze of 37 ohms, surprised me as thought it was a tncs- Victorian house, Db from 1989, no docs- could it be a TT off the water main? 10mm bonding to gas and another 10mm out of sight. The met on the rhs of tncs
block not connected to neutral- can anyone help me with some ideas? Cheers.

 

[BOYD BARKLEY]

You should keep an eye on the 18th. It has a few things to say about this

Chapter 54
CLICK

Thankyou. Here we go again, many questions will follow the path of
ambiguity. They love it don't they !

 

[mjb]

Looks like a TNS from a lead covered cable.
Originally supply cables did not provide an earth point the lead just providing protection for the cable, so many services are actually TNS with no earth terminal.

 

[Nigel]

Did you ky disconnect all parrellel paths before doing the Ze test?

 

[stevels4]

The earth block runs into the terminal and there is space for a link, the neighbour's block is identical and has a link- here's the a pic of the next door one...View attachment 41076

That is TNS.

 

[davesparks]

The earth block runs into the terminal and there is space for a link, the neighbour's block is identical and has a link- here's the a pic of the next door one...View attachment 41076

That is a TNS cutout fed by a split concentric cable, you can just see the bare earth conductors connected to the earth terminal internally.

However this begs the question of why you are breaking the seals and taking cutouts apart?

 

[davesparks]

If that's the the case and yo've got 37 ohms yo've cracked it any thing under 100 is fine.

Where did you get that bit of nonsense from? Direct from the -------- generator at NICEIC headquarters?

 

[BOYD BARKLEY]

Where did you get that bit of nonsense from? Direct from the ******** generator at NICEIC headquarters?

For embedded metal work or earth rod ********

Where did you get that bit of nonsense from? Direct from the ******** generator at NICEIC headquarters?

 

[davesparks]

For embedded metal work or earth rod ********

Eh? I asked where you got that value from, not what you were referring to.

 

[BOYD BARKLEY]

Eh? I asked where you got that value from, not what you were referring to.

200 Ohms is the value recommended not to be exceeded in regs, as you well kn0w . Yes NICEIC do recommend under 100. For an earth electrode. So far as the nonsense is concerned(I'll be objective here not obstructive)If you look at B.S.7430 IT RECOMMENDS 100 ohms max and 2 meters of rod as the top meter of soil can be unreliable. Eh?

 

[Sylvia Namusisi]

@James Kinrosd. A water pipe can be used with the owners permission .

Not with the current regs,it will not comply.You would have to drive a new earth electrode down.

 

[Sylvia Namusisi]

No

I was under the impression that you can only use a water pipe of it's your own private supply ..

No Sir,not allowed private or public.

 

[sparksburnout]

No
No Sir,not allowed private or public.

Oooerr Mrs.

 

[DPG]

No
No Sir,not allowed private or public.

Thought under certain conditions it was allowed .

 

[Octopus]

No
No Sir,not allowed private or public.

Reg number?

 

[sparksburnout]

Reg number?

 

[Octopus]

No
No Sir,not allowed private or public.

Maybe you need to read 542.2.6 BYB again .................

 

[Sylvia Namusisi]

Maybe you need to read 542.2.6 BYB again .................

Yes true ,that is the reg no.thank you.

 

[DPG]

Yes true ,that is the reg no.thank you.

And does it say that it is completely prohibited to ever use a water pipe??

 

[Octopus]

And does it say that it is completely prohibited to ever use a water pipe??

No it doesn't ...

 

[Sylvia Namusisi]

And does it say that it is completely prohibited to ever use a water pipe??

Yes, last sentence of 542.2.6 -Other metallic water supply pipework shall not be used as an earth electrode unless precautions are taken against its removal and it has been considered for such a use.

 

[Strima]

Yes, last sentence of 542.2.6 -Other metallic water supply pipework shall not be used as an earth electrode unless precautions are taken against its removal and it has been considered for such a use.

So it can be used.

 

[DPG]

Yes, last sentence of 542.2.6 -Other metallic water supply pipework shall not be used as an earth electrode unless precautions are taken against its removal and it has been considered for such a use.

Hoist by your own petard it would seem.

 

[BOYD BARKLEY]

200 Ohms is the value recommended not to be exceeded in regs, as you well kn0w . Yes NICEIC do recommend under 100. For an earth electrode. So far as the nonsense is concerned(I'll be objective here not obstructive)If you look at B.S.7430 IT RECOMMENDS 100 ohms max and 2 meters of rod as the top meter of soil can be unreliable. Eh?

542.2.6 Says other metallic water supply work can't be used unless
precautions are taken and it's been considered for use. So if you'r
desperate and can understand what that means, and what ''Other''
is and you can be bothered with all the hassel , you can. Maybe.

 

[Octopus]

Yes, last sentence of 542.2.6 -Other metallic water supply pipework shall not be used as an earth electrode unless precautions are taken against its removal and it has been considered for such a use.

Keep digging ...........

the important part is highlighted above.

 

[BOYD BARKLEY]

Keep digging ...........

the important part is highlighted above.

Yes it's all there