Earthing Set-up
- Thread starter LLGS
- Start date
I've worked on a supply fed direct from a substation which was supplied like that with 6491X, but never seen a direct supply as small as the OPs fed in that way.
Also I have worked on CT chamber incommers with a 6491X along side the incommer, but I forget what the earthing supply type was. I have a feeling it was TN-C-S with the earth attatched to the CNE conductor presumably going to a DNO rod?
Fair enough.
Would it still count as TN-C-S if the split of the CNE were outside of the consumer's property?
Kind Regards, John
No, but then again it would be a neutral supply rather than a CNE in that case, and the two wouldn't be connected together at the CT chamber.
If a largish customer is fed directly from a substation by a piece of U/G main we would be obliged to also provide an earth rod at the termination to comply with PME regs.
Usually the combined N/E sheath would be terminated inside the termination with a separate 70mm2 earth wire connected to the same point (often externally) going back out to the earth rod.
Hard to tell but the service cable in the o/p looks as though it could be PVC sheathed.
I think that's the exact setup I was trying to describe!!
Thanks Westie
Thanks Westie
Aren't we both saying the same thing - i.e. that it would be TN-S as far as the consumer was concerned, since the N and 'earth' would enter the property separately, even though there was a CNE conductor before it split into N & E somewhere external to the property?
Kind Regards, John
For the average consumer in the average house in the average street it would be TN-S but for the more discerning consumer who has anxiety about his or her CPC not being at true ground potential this set up would not be TN-S
No cpc is ever at true ground potential except where it enters the ground.
... and, even then, it won't be at the true potential of the mass of the earth if there is any current flowing down it.
Kind Regards, John
Thank you very much for all the responses - I've added another photo which I hope is clearer. We're a terraced office building based in North London if that has any bearing on what is 'average' for the area. I'm putting a job on rated people so hopefully someone will be able to come and investigate further.
It is an odd one, I would say TN-S, the earth coming in with the black service cable being your earth, but you would need to have it tested to be sure.
The earth could easily go out through that same old clay duct and end up on an earth rod, so it really needs testing.
It would be odd for the DNO to run in an earth like that.
The earth could easily go out through that same old clay duct and end up on an earth rod, so it really needs testing.
It would be odd for the DNO to run in an earth like that.
Just go to one of the approved scheme websites for example NICEIC and do a search for an approved contractor (ignore the results which are only domestic installer).
As it is at the moment it ought to be isolated as it appears to be dangerous.
As it is at the moment it ought to be isolated as it appears to be dangerous.
It could be dangerous - but it surely all depends where that G/Y goes? The cutout looks pretty new doesn't it? Whoever installed it presumably must have been happy about the earthing arrangement?
Kind Regards, John.
None of the earths go to any of the electrical equipment in the photo (bar the MET). One comes in (maybe) and the other goes to the gas pipe.
So on the grounds that there isn't an earthing conductor I'll err on the side of caution and say it ought to be isolated.
So on the grounds that there isn't an earthing conductor I'll err on the side of caution and say it ought to be isolated.
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