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It looks like an old TNS and now its been converted to a TNC-S and they have just left the clamp on, contact the DNO, most of the UK DNO'S only have TNC-S now and its not a TT .

Regards Chris

If it is a PME connection, then there a big problem with it, having a Ze of 0.54 ohm !! lol!!!
No, this is in all likelihood a non DNO connection, made by either an incompetent electrician or trainee or DIY'er who's knows no different!!

No idea about where you live Chris, but i'm reliably told in the Essex area the DNO are still providing TN-S to new builds in areas where TN-S is still the local network system. But i agree with you, most of the much older DNO TN-S networks are now being converted to TNC-S(PME) especially where sheaths are known to be breaking down with age.
 
Tony, E54,
I can't believe that you are still trying to justify your advice.

YOU both, may, well be competent to remove the clamp.

YOU BOTH missed my point.

On a public internet forum, you advised the OP to break the law, and to undertake works that could have injured or killed him.
You had no idea of his background or training, the only information you had was the post and a small poor quality picture.
You both know the state of the industry in the UK, yet you both advised a person of unknown competence to undertake a task, which in the area of the job, the local DNO will not do as they have classed it more dangerous than a live cable cut.

That is my point and I still stand that by it, that your advice was incompetent.

How would you have felt if the next post on the OP's account had been from his widow explaining how he had followed your advice and the cable had blown and caused him to react and be electrocuted, and that his family had now lost their bread winner, she had lost her husband, and his children were now without a father.

You did not know enough about the OP, the situation, the condition of the cable, or the site, or in fact anything to make such a rash and possibly dangerous suggestion.

You both have probably done this on industrial sites in the past, where there is a lot of support and others around.
You may have done this when you were the only person around for miles.

In the WPD area there are a lot of 951 clamps and jubilee clip type connections having been made to their network over the years.
I have not had any of their people admit as to who made these connections, however, when you look at the numbers, then it was certainly not the odd spark or DIY'er.

They have had incidents and reportable accidents when removing these clamps, thus they no longer do it unless they have to.
The cumulative experience of WPD is that to remove one is more dangerous than to leave it, and is also more dangerous than to undertake a controlled, clean, live cut, on an undamaged cable.

So then it appears that between you you are more competent than all of the engineers, technicians and linesmen working for WPD, good on you.

I still think and will continue to think that you were and still are well out of order advising a completely unknown person to tamper with the national grid and undertake a task which is known by the DNO in the area he is doing it as life threatening.

As far as the work I do, yes I do have a lot of work, some of it has to be done live, I work for private domestic clients, for public sector bodies, such as the local authority, schools, and health boards, local & national companies, from sole traders, through SME's to large multinational blue chip organisations, quangos & HM Gov't departments.

One of the reasons I am not on here so much is that I am very busy at the moment.

I not only undertake the actual physical works, but I also undertake the design and the consultancy.

Oh and no Tony as the last paragraph suggests I don't actually work for the HSE, however, I do know a few of their inspectors including the local electrical and controls systems specialists.

I know the legislation and regulations because it is my job to know it.
 
I have no idea what your trying to prove here, or who you are trying to impress, but by assuming and/or putting words into my mouth isn't going to get you very far with me!!

I've been around in this industry far too long to be told, that a controlled clean cut of a live cable is less dangerous than removing a jubilee clip. They only time that would come close to being the case, is if that jubilee clip had been tightened to the point, that it had buried itself deep into the lead sheath, and that is clearly not the case here. ....And yes i am competent enough to assess that fact, from the photo provided by the OP!!

By the way, that WPD of yours must have some real cowboy's in their employ, if what you say is correct about all these jubilee clips and 951 clamps they have been installing. From what i can make of your post, it was these WPD employee's buckshee earth connections that they declared too dangerous to remove, ...in the first place!!

You seem to like glossing things up beyond any real recognition, were not talking about the National Grid here, were talking about a local network cable. The difference between them is massive, which is the same as you are trying to make out here. Wrapping a constant force spring clamp around a sound cable sheath is not going to blow up anything, nor is it dangerous by anyone's stretch of imagination, No-ones making any live connections to anything, no-one needs to break any seals, and your not even using any tools for god's sake!!! As regards to the OP's competency, maybe i should have enquired a little deeper, but hey, widows and things, you certainly have some imagination there!!! Geezus!!

The fact that it's against the rules, is neither here or there, and you have made the point which is also fair enough. So what is that different from you breaking the rules when it suits you, and anyone else??

You have turned this into one massive fiasco, coming out with wild and inaccurate statements, along with frankly insulting accusations about my own and Tony's competency. when there was really no need or reason to do so. It just suited your ego at the time to do so!! I really don't need you to tell me if i'm competent or not. Apart from knowing myself, i'll leave that to my present and past employers, who to date, have seemed to be more than satisfied in this regard!!

You can continue to think whatever you like of me, if you think it that will concern me, your going to be sadly mistaken. So long as just think it, and don't voice it, that's fine by me!!
 
Paul at the moment I’m still seething.
You call both E54’s and my skill and competence in to question. Based on what? Can you provide any documentary evidence of the danger of removing an earth clamp, you seem to base everything on what’s in black and white, but then resort to “conversations” with your friends. Down the years I trained with a Regional Electricity Board (as they were then) to do live jointing. It wasn’t that I needed it, but the company I worked for thought it would be beneficial for me to gain the experience and knowledge of what can be done. I know what I consider safest, removing a clamp is a small risk. If you look at the construction of a cable you will find that due to the layered nature of a paper lead with it’s infill of oil/wax it is far more resilient than a modern cable.

I took the photo of the clamp in to Photoshop so I could have a very close look at it. I did this before I said anything because as you know my eyesight isn’t what it could be. There is no indentation of the lead. Fitting a constant pressure spring and braid requires no tools and forms it’s self to the contour of the sheath. The DNO’s use Hepworth clamps which require the use of a tool that if it slips could puncture a lead sheath.

At the moment I think an apology to E54 and myself is in order.


But on a personal note I think this is getting totally out of hand!
 
If it is a PME connection, then there a big problem with it, having a Ze of 0.54 ohm !! lol!!!

Well, Eon state in there Earthing manual for TNC-S upto 0.8 not 0.35, obviously you wouldn't get a 100 amp without an RCD. lol

No, this is in all likelihood a non DNO connection, made by either an incompetent electrician or trainee or DIY'er who's knows no different!!

Possibly, though if it is a tns a test of the two loops should give an indication.

No idea about where you live Chris, but i'm reliably told in the Essex area the DNO are still providing TN-S to new builds in areas where TN-S is still the local network system. But i agree with you, most of the much older DNO TN-S networks are now being converted to TNC-S(PME) especially where sheaths are known to be breaking down with
age.

Eon are totally free of TNS now, well so they have informed me lol, if it aint TNC-S it TT lol


Regards Chris
 
Well, Eon state in there Earthing manual for TNC-S upto 0.8 not 0.35, obviously you wouldn't get a 100 amp without an RCD. lol

Tha's strange, i've not heard of that before. PME has always, as far as i know had a maximum Ze of 0.35 ohm. I'm just wondering if they have started PME'ing all there old TN-S local networks and haven't finished any, thus still relying on the lead sheath of the TN-S cables as the max level!! Who knows, with these new DNO's!! lol!!


Possibly, though if it is a tns a test of the two loops should give an indication.

Agree, it's about the only way your going to get a good indication of what system is actually being provided here...


Eon are totally free of TNS now, well so they have informed me lol, if it aint TNC-S it TT lol

Are Eon only in your area, or do they cover other old regional boards around the country??
 
Well there is no defined limit with ESQCR, so Eon work to three limits dependent upon Fuse size. Where they have in-fill developments and service alterations higher value can be expected and you need to design accordingly.

They pretty much cover the midlands and down into bath and Hereford i think.

Regards Chris
 
doesnt sound right to me set a standard and stick to it , No TNS Eon are always round here and i would say 50% of supplies are TNS
 
Last edited by a moderator:
doesnt sound right to me set a standard and stick to it , No TNS Eon are always round here and i would say 50% of supplies are TNS

Thing is Nick, that doesn't necessarily mean that the local network hasn't been PME'd. It can still appear at the service cut out as a TN-S supply. You will still apply TN-S requirements, whether you know or don't know the DNO side has been PME'd... In other words you go by what you see at the service cut-out!! lol!!
 
Constant Force Springs : 3M UK & Ireland

There are two springs and enough braid in a kit for two cables.

Or you could use a Hepworth clamp which the DNO uses, but you need a special tool to apply them.
http://www.sicame.co.uk/Section8/8.05-8.06.pdf

Hi there.

Those constant force springs.

Are they like a wrap around arrangement, you know like you uncoil them and then recoil them around the lead sheath?

I have been looking at some pictures of installation and the pictures are not very clear.

I am not about to do this I am asking out of curiosity.

There are loads of TN-S cables around this area fitted with bonding clamps.
 
Hi there.

Those constant force springs.

Are they like a wrap around arrangement, you know like you uncoil them and then recoil them around the lead sheath?

I have been looking at some pictures of installation and the pictures are not very clear.

I am not about to do this I am asking out of curiosity.

There are loads of TN-S cables around this area fitted with bonding clamps.


NO you don't uncoil them... You lift the outer free end, place inner face of the spring coil on the cable armouring, and walk/unroll it around the cable. Placing the braided earth conductor under the second and then again under the forth or fifth turn. Always a better job to seal the spring clamp and braid termination with amalgamating tape, or on new installations with a length of glued heatshrink!! These constant pressure spring clamps are also used in many types of buried cable joints, from the heat shrink variety to the poured epoxy types etc...
 
its cable sheath, (tns) clues- .54, high for pme, and this is not a pme service.

That was my thoughts on this service head earthing arrangement. Obviously a DIY connection, that didn't have a clue what they were doing. Probably thought the Neutral earth connector on the cut out, was a normal earthing point...lol!!
The other give away, is the lack of DNO PME stickers all over the service cut out!!
 

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