Pme not

Guest111 · Sep 13, 2013

went to do some work for a relative today,change CU and a few odds and ends in a small shop which they have just rented,the landlord is a distant relative of theirs and has said they can do what they want.Anyway I was doing a few tests and found that the Zs on a radial was 400 ohms,Disconnected earth bonds at CU and tried to do a Ze,tester went into lockout straight away,anyway tested phase to neutral at cutout and got 240v tested phase to earth and nothing,it was a PME system so something very wrong. Anyway puts a call in to networks and about 2 hours later a guy came out and I explained the problem,he opened up the service head to find that a link had not been fitted between the neutral and earth,this was from 20 years ago when the new cable was fitted.He was not happy and neither was I it proves that not only was it not tested by networks when it was fitted,but obviously it has never been tested since,if this isnt a good advert for regular I&T then I don't know what is.

Tiny Spark · Sep 13, 2013

Bloody hell....
Thankfully it has been found, but it makes you wonder how many others are like this.

Guest111 · Sep 13, 2013

Tiny Spark said:
Bloody hell....
Thankfully it has been found, but it makes you wonder how many others are like this.

Yeah I explained to the guy from DNO that there were about 6 other properties had their feeders replaced at the same time,his reply was "well I ain't knocking on doors when they shout we'll deal with it".Amazing!

SPARTYKUS · Sep 13, 2013

phil d said:
Yeah I explained to the guy from DNO that there were about 6 other properties had their feeders replaced at the same time,his reply was "well I ain't knocking on doors when they shout we'll deal with it".Amazing!

somehow, the 'like' button doesnt seem appropriate!

telectrix · Sep 13, 2013

so he knows there's some potentially extremely dangerous installations, and won't act upon it. FFS, what a merchant banker.

Des 56 · Sep 13, 2013

Perhaps phill there was no Pme available 20 years ago and these were just assumed to be so by the non testing tester/installer

Thats one reason the link may be missing,but it seems to be folly on a grande scale for them to dismiss the problem you found for them

and them not taking action

Have they no moral duty to the safety of the user anymore

VoltzElectrical · Sep 13, 2013

street lighting sparks where I am now don't even know or want to know about earth fault loop impedance.

I test everything, and the faults I have come up with have generated a LOT of work for the digging and jointing teams. Anywhere from no earth at all, all the way down to 7 ohms.

The biggest problem is with the aluminium cable, and the lack of compound to counteract the effect of galvanic corrosion.

I've learned a lot about testing since starting this job, and if anyone is in any doubt about it's importance, then please think again.

Switching on and hoping for the best is...just that. HOPING for the best.

GLENNSPARK · Sep 14, 2013

telectrix said:
so he knows there's some potentially extremely dangerous installations, and won't act upon it. FFS, what a merchant banker.

listen....
went to a place earlier ....took one look at the cutout (cast iron)....and thought straight away (you can tell by looking at em) fused neutral inside....
so pops the cover and...yep....a pair of 40A BS3036s...this was at about 7.00pm ish....
i was straight on to the phone for the lady...
DNO said 8 weeks...

mechelec · Sep 14, 2013

This can be a problem when the DNO use a cutout that is not PME specific ie can be used for PME or SNE. On a PME supply the link is not fitted but on some cut outs the usual earth terminal is exposed on the side but is not connected to neutral with link. Along come sparky, Electrical Trainee or DIYer and sticks earth in without testing and you get the problem you have comes across. DNO can't be responsible for checking what earth has been connected their cut outs as there is all sorts of DIY PME's installed and bonding clamps fitted to lead sheaths etc.

mechelec · Sep 14, 2013

GLENNSPARK said:
listen....
went to a place earlier ....took one look at the cutout (cast iron)....and thought straight away (you can tell by looking at em) fused neutral inside....
so pops the cover and...yep....a pair of 40A BS3036s...this was at about 7.00pm ish....
i was straight on to the phone for the lady...
DNO said 8 weeks...

Well it had been like it since the 50's so can't be that urgent can it ???????

Engineer54 · Sep 14, 2013

mechelec said:
Well it had been like it since the 50's so can't be that urgent can it ???????

That old chestnut is no excuse!! That's the same as a householder saying he doesn't want to pay for any bonding done to his installation, as it's been fine for the last XX amount of years!!

Then there is the fact, that all the DNO's were instructed to replace all the old cast iron cut-out's with DP ceramic rewireable fuses... And that was supposed to have been completed by the end of 2011!! lol!!

Des 56 · Sep 14, 2013

Engineer54 said:
That old chestnut is no excuse!! That's the same as a householder saying he doesn't want to pay for any bonding done to his installation, as it's been fine for the last XX amount of years!!

Then there is the fact, that all the DNO's were instructed to replace all the old cast iron cut-out's with DP ceramic rewireable fuses... And that was supposed to have been completed by the end of 2011!! lol!!

Here is a link
http://webarchive.nationalarchives.gov.uk/+/http://www.berr.gov.uk/files/file26709.pdf

Page 17 7(2) has some interesting guidance on fused neutrals and old cut outs

Engineer54 · Sep 14, 2013

Des 56 said:
Here is a link
http://webarchive.nationalarchives.gov.uk/+/http://www.berr.gov.uk/files/file26709.pdf

Page 17 7(2) has some interesting guidance on fused neutrals and old cut outs

That cut off date seems to have been ammended to 2013. As far as i can remember the 2011 date was brought about by DNO staff and it's contractors being put at undue risk of old cut-outs by ceramic rewirables breaking apart while being pulled and not just DP fused neutral examples. It had nothing to do with maintaining Neutral connections, though understandably is just as important.

I know from an ex DNO Area manager friend, that several accidents had been recorded among the UK's various DNO staff, due to these old fatigued ceramic cut outs. Think it was Ofgem that ordered the removal of all such equipment after complaints and safety representations by trade associations/unions...

Guest111 · Sep 14, 2013

the earth block was inside the cutout,behind the seal,so it was definately a DNO cock up

GLENNSPARK · Sep 15, 2013

Engineer54 said:
That cut off date seems to have been ammended to 2013. As far as i can remember the 2011 date was brought about by DNO staff and it's contractors being put at undue risk of old cut-outs by ceramic rewirables breaking apart while being pulled and not just DP fused neutral examples. It had nothing to do with maintaining Neutral connections, though understandably is just as important.

I know from an ex DNO Area manager friend, that several accidents had been recorded among the UK's various DNO staff, due to these old fatigued ceramic cut outs. Think it was Ofgem that ordered the removal of all such equipment after complaints and safety representations by trade associations/unions...

the long n short of it `ere is i`m not preparared to walk off and leave a potential at this gaff....