TN-S earthing query

[Stephen-d]

Hi everyone,
This might be a silly question but I have been asked to look at job where they would like a new garage supply, its a old property with the re-wireable fuse board but previously someone has tapped off the meter to an additional RCD unit which was used for a shower (no longer required). They do plan on doing a board upgrade, but at the moment they could do with power in the garage. So my thought are i could use the RCD unit to feed the garage and use a main switch consumer unit in the garage for the time being. My question is in regards to the TN-S, it looks like a old supply with stranded cable with no insulation? Would this earth still be ok to use providing the earthing to the RCD unit is 16mm? Or would the DNO have to upgrade their earth first?
Thanks

 

[Taylortwocities]

I think so, but I will double check when I go back there. I will test it before doing any work as well

Well, you surely will be doing a Ze measurement as a matter of course.

they might come out upgrade the earth to 16mm

not for a TNS they won’t.

PS apologies for the negative tone!

 

[Dartlec]

Well, you surely will be doing a Ze measurement as a matter of course.

not for a TNS they won’t.

PS apologies for the negative tone!

Might vary (my experience is with UKPN), but I've found them fairly good at coming out and looking at least (if a bit delayed)

If the earth is correctly soldered on then they may well not upgrade it - but the amount of bare metal on show might make them at least retape it.

That's assuming that Ze is acceptable of course. My guess is that it will be fine - most of the "TN-S" arrangements around here are more or less PME in all but name anyway from where they've been upgrading the network and its been a long time since I got anything over 0.2.

If nothing else, if they come out for a safety check, take one look and say "nothing needs doing", then you've done what you can and it's noted somewhere should there ever be a problem and questions are asked...

 

[ipf]

A Hepworth spring clip is generally used for repairs....but I'd wager there's nowt wrong with that connection.

 

[Stephen-d]

Well, you surely will be doing a Ze measurement as a matter of course.

not for a TNS they won’t.

PS apologies for the negative tone!

Yes of course, I will be doing that before i do any work. I just wanted to check that it was ok to use (providing the test results are ok) before i got stuck into anything. I am not so experienced with the older properties / supplies

 

[Stephen-d]

I'd say that's a definite TN-S - the stranded cable makes it appear original, although the amount of bare cable sheath on show makes me wonder if it was a repair at some point, either by DNO or someone else.

When I first saw one like this I assumed the earth block was internally connected to make a nice TN-C-S, but no - just provided for convenience of connecting earths...

Might be worth a call to 105 and picture - they might come out upgrade the earth to 16mm - they usually use some form of clip these days to reconnect the earth - then they'd probably tape everything up so no metal on show. Or there might even be a way to convert it to PME, though can't see an immediate option in that photo.

They are fairly good for upgrading earths around here (UKPN) - about 8 weeks wait though unless it's an actual issue with no earth - but you don't need to be there if you've left everything ready....

No chance that they'll upgrade the actual head though I'd say -

Looks like the seal fairy has paid a visit previously as you say, so might be a good time to try and get a henley block in somewhere, if only to make it easier later.

Are there two feeds coming out of the meter? Is the meter seal broken, or does it have separate ones for incoming/outgoing? If nothing else then I'd get that notified to the electricity supplier so they can choose if they want to correct that.

Can't see from the photo, but if there's enough slack from the meter to the boards, it might be possible to insert a henley block now, and then the extra feed can be removed by the meter supplier?

If i remember correctly the meter has two feeds coming out, so one feed in and two feeds out and i think the meter seal had been removed as well which i assume was the same seal fairy that did both. I think the henley blocks are a good idea, it makes sense.

 

[Stephen-d]

Whatever's needed, it wants sorting. Can't see it on the photo.

Seems a bit unusual......someone breaking into a meter to pick up a supply and not by passing.?? Thicko or DIY, maybe?

I didn't understand it myself surly it would have been easier installing henley blocks than trying to tap off the meter?