What is this earthing arrangemenmt?

[1Justin]

I came across this one yesterday. Not touched it yet, but got any idea what's going on here?

It kind of looks like the upper bare Earthing Conductor to MET might be Earth/Neutral from inside the head, meaning TNCS. (or it might be from a wrap to the sheath inside the head, making it TNS?). The cut-down diameter in the cable before the head implies any sheath is possibly removed above the oiled paper wrap, meaning TNCS more likely.

..But then there is the old lower Earthing conductor which appears to be a wrap/clamp which I assume must therfore come off a TNS sheath which disappears into the wall. (Perhaps it goes to defunct Cu water pipe). The old lower one is solid copper and quite substantial. I have no idea where it goes to, there is nothing visible.

Zs sockets measures 0.3R.

Quality of that Earthing conductor:
I will probably verify Earthing conductor with Adiabatic eq'n once I get on site. Doing this backwards shows I could get away with 6mm^2 for Ze down to 0.1 (I have not yet measured Ze). I have six strands here, so we'll probably have at least 6mm^2 (a vernier job). Mechanical protection of earthing conductor is another matter - I would need to add a cover to comply with 542.3.1. So I can't argue necessarily this earth is non compliant, and I assume DNO wouldn't then take any responsibility to improve this for free? - Or is it worth getting them in?) .

 

[telectrix]

looks a bit of a mess. i'd be inclined to get DNO to sort it out.

 

[Engineer54]

This looks like a compound sealed service cut-out so is unlikely that there is a N-E connection but you can check by removing the neutral sides coverplate and see if there is 2 connections to the neutral terminal!!. The lower earth connection to the DNO cable could well be to an auxiliary earth electrode, ...that was a fairly common practice in the 50's.

Can't make out what's happening at the top end of the cable, the photo is just too dark to distinquish anything!! lol!!

 

[driverman]

Clutching @ straws here, but could there be another DNO supply which supplies a neighbouring property? In other words back to back supplies to each property. Possibly pinched an earth from the U\G cable in your photo. Is there a neighbouring property?
I did come across something like this many years ago. There was a loop service taken to the n/bours property directly form within the cutout. Just couldn't see it! If nothing else shows up......Get the DNO in.

 

[1Justin]

Hi Driverman.

Thanks, that's interesting. And I'll do that first thing when (if) I get the job.

Does anyone by any chance have a phone number for DNO engineering for Seeboard? I can't find one on the web, I keep getting directed back to EDF customer number which isn't much help.

 

[1Justin]

Engineer54. "Auxilary Earth electrode". OK, if that WERE the case would you still describe this as TNx or as TT?
And disconnection times would be..?

 

[worzol99]

Looks to me like a old stainless steel wall fixing more commonly used with conduit, cant remember what there called though

 

[guest119]

That is a crampet going into a rawlplug.
You have tns.

Boydy

 

[1Justin]

Ha ha Boydy. - Yes of course. I only came across "Crampets" the other day. - I'm more familiar with Crumpets.

Not entirely sure why it was needed there, but it makes sense now.

Rgds

 

[Stroppy]

So it is, well spotted Boydy. Its sort-of clipping the incoming cable to the wall.

 

[guest119]

Hot cross buns this week, not crumpets:wink_smile:

 

[Engineer54]

Engineer54. "Auxilary Earth electrode". OK, if that WERE the case would you still describe this as TNx or as TT?
And disconnection times would be..?

Of course it would still be a TN-S system, certainly not going to be a TT system is it!! It was common practice in the 50's, especially on council housing estates!!

 

[1Justin]

Yes it would be Thanks.
Anyhow we seem to have tracked down the actual animal. - But I'll look out for those Auxilary electrodes in the future.
Rgds

 

[Guitarist]

I wonder just how far that crampet could penetrate with a bit of movement...