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Topic Title: Safe use of a compression gland
Topic Summary: Regulations
Created On: 09 November 2012 10:51 AM
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 09 November 2012 10:51 AM
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Avatar for ewan29                                            .
ewan29

Posts: 8
Joined: 25 July 2008

I have found an installation that has 2 twin and earth cables tie wrapped to a 150mm cable tray and enter the distribution board via a single plastic compression gland.
I know that this is wrong and I would like to discipline the electricians involved but I need to know what regulation this contravenes.

Can anybody help?

This is a serious breach of Health and Safety and a very serious embarrassment with the client.
 09 November 2012 11:02 AM
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BigRed

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What reg is it breaking then?
 09 November 2012 11:05 AM
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Yooj

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Can you expand a bit and explain why you feel that this is deemed to be a serious breach of H&S?

Yooj
 09 November 2012 11:20 AM
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Avatar for ewan29                                            .
ewan29

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I'm not sure what regulation it contravenes but I wouldn't think that a non mechanically protected cable would have been allowed on a cable tray in a heavy industrial area. And secondly I wouldn't have thought you could put 2 solid multicore cables (the twin and earths) through the same compression gland.
I would love to attach a photo but I'm not sure how.
 09 November 2012 11:27 AM
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AJJewsbury

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I have found an installation that has 2 twin and earth cables tie wrapped to a 150mm cable tray and enter the distribution board via a single plastic compression gland.
I know that this is wrong and I would like to discipline the electricians involved but I need to know what regulation this contravenes.

cable ties on tray sounds OK to me (you can buy special tray type ties which snap in two and lock into the slots - using an ordinary tie doesn't seem any worse - just less convenient to install).

You can get compression glands with specially shaped grommets especially for T&E, so in principle there's no objection to squeezing the cable a bit - indeed many cable grips (e.g. in downlighter joint boxes) work on the same principle.

Clearly shoving two cables into one gland isn't going to provide proper sealing - but is sealing necessary in that particular situation? If a simple rubber grommet would have been acceptable, the gland doesn't seem any worse.

The only likely non-conformity I can think of is that if it's on an accessible upper surface of the DB, then it might not meet the required IP 4X requirement - but that's a pretty minor infringement (it's a relatively new requirement and thousands of existing installations never achieved that and haven't had any real problems with dust ingress).

Seems a bit rough, but probably stretching a point to go down the 'good workmanship and proper materials' route.

Unless there's anything unusual about the situation (special location, outdoors etc).

- Andy.
 09 November 2012 11:35 AM
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AJJewsbury

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heavy industrial area

Ah, you didn't mention that before!

What usually happens in the area where the cable is? Lots of flying lumps of metal? Are ordinary flexes on power tools banned there?

I would love to attach a photo but I'm not sure how.

You can't post photos directly, but you can upload them to a suitable hosting site (e.g. photobucket) and post a link to it here (if you're a new user, a more trusted user might have to re-post your link to make it visible to everyone, but don't worry about that for now).

- Andy.
 09 November 2012 11:44 AM
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OMS

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As a principle Ewan, I would agree with you that the installation method and workmanship is sub-standard - I'm not sure I would agree with serious H&S failings though - no has died yet, nor are they likely to unless you can show what fault sequence will damage that cable in such a manner that it presents a hazard - equally, without knowing the gland size (and if it has been tightened) then damage to oval cable sections in a circular compression is a matter of debate and may well require accelerated testing to show a potential for damage. This could include a pull out force test

I guess i have to ask - who was the designer, and was he given a specification or requirements document to work from. I'd be happy that the designer may well not have addressed his obligations under the CDM regulations, particularly with regard ongoing maintenance) and it would be easy from a BS 7671 perspective to show that several regulations are potentially breached (generally around the Chapter 52 area). You could also argue that with two T&E's entering a stuffing gland then the gland is being used outside the scope of BS EN 50262:1999 and thus a breach of 133.1.1 - Regs 132.5.1 and 133.3 may also be breached

Regards

OMS

-------------------------
Failure is always an option
 09 November 2012 11:48 AM
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Avatar for ewan29                                            .
ewan29

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http://i1290.photobucket.com/a...Ewan_J_Kerr/Carst.jpg

I have linked the photo. I hope it works
 09 November 2012 12:21 PM
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OMS

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You could add potentially a lack of fire stopping where the T&E's exit the compartment

The floating green and yellow pig tail with a crimp going nowhere might be worthy of a comment as well.

If it's a site standard - lack of cable identification would be another observation.

It looks pretty poor Ewan - but I think any disciplinary action would first need to look at what they were asked to do, by who and in what contractual capacity. It could be argued that it's the design that's incorrect fundamentally - the installation is poor, yes - but that stems from the design

Regards

OMS

-------------------------
Failure is always an option
 09 November 2012 12:31 PM
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potential

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The photo isn't that clear but it would appear to me that there is a potential risk of damage to the T/E caused by the edge of the tray.
 09 November 2012 12:40 PM
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AJJewsbury

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The plaster magnolia emulsion finish doesn't give the impression of heavy industry. Does the T&E lead out to less dainty areas?

One other thought is the ability of T&E (with its reduced c.s.a. c.p.c.s) to withstand fault currents - which are often higher in commercial/industrial premises than domestic. I can't tell the cable size or MCB rating/type but prospective earth fault currents over 3kA would probably stand a bit of further examination.

- Andy.
 09 November 2012 12:44 PM
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Yooj

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It's rough, no question, and as OMS said, a bit of intumescent mastic would not go amiss. But, I would say that it was not a serious H&S risk though.

Where is the DB located? Is it in an open space, or in an electrical cupboard or such like?

Yooj
 09 November 2012 02:58 PM
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Delbot321

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Looking at the original post it sounds to me like the client has bent your ear a bit and you are looking to discipline someone as a way to passify yourself and the client. Start at the beginning of the process - fact find from the electrican as to what their job instructions were and by whom, were they asked to do it that way, was it sub-contracted to them on a price.

From the photo its not ideal BUT I can't see it failing an EICR so not sure how it can be a 'serious' breach if H&S. The gland is better than an ordinary grommet.

One other observation - are the 2 twin & earth cables part of a three phase circuit - hence why they put them in the same hole?
 09 November 2012 03:14 PM
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rocknroll

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So what you are all saying is you have been fooled by the 'illusion' again' because it is untidy or 'ruff' as you say it must therefore look unsafe but if it was neat with the T&E's straight and evenly spaced clipping or ties it would look safe, I suppose its hard work being perfect.


regards

-------------------------
"Take nothing but a picture,
leave nothing but footprints!"
-------------------------
"Oh! The drama of it all."
-------------------------
"You can throw all the philosophy you like at the problem, but at the end of the day it's just basic electrical theory!"
-------------------------
 09 November 2012 03:25 PM
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Avatar for ewan29                                            .
ewan29

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Thanks for all the comments they are greatly appreciated.

The installation is from a 3ph Merlin Gerin DB supplying sewage treatment equipment. The dist board is on a brick and plaster wall and the room contains your standard 1960s MEM switchboard and busbars etc. What you don't see in the picture is the 4" metal trunking and all the other switched fuses.

Our client is a water authority and have a very strict specification, this work falls short of complying with that specification. The electrical design was for 2 x 2core 1.5mm XLPE/SWA/PVC cables with CS glands, the intumescent seal was also on the design. The installation team disgregarded the design and installed this instead.

They will be under investigation for a disciplinery and I had hoped that we could have found more than just poor quality workmanship and a disregard of the design to use in the disciplinery.
 09 November 2012 03:29 PM
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Avatar for OMS.
OMS

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Originally posted by: rocknroll

So what you are all saying is you have been fooled by the 'illusion' again' because it is untidy or 'ruff' as you say it must therefore look unsafe but if it was neat with the T&E's straight and evenly spaced clipping or ties it would look safe, I suppose its hard work being perfect.



regards


Not really, old chum - these circuits appear to exit into an industrial area - probably evidenced by the existing swa's that are installed in a pretty workmanlike manner. And two T&E's into a single stuffing gland is R.A.F - even being an ex DX boy, you'll know that, and thier standads are pretty low.

It's not pretty for sure - but I'm less concerned by that - but what do i know - if the OP pays me, I'll rip the instalation apart and give him a report full of "arbut whatif" and a few reg numbers as to why millions will die - if the installer pays me, I'll defend it with plenty of "that's not a credible arbut whatif" and "unsubstantiated innuendo" with the same reg numbers and give the whole thing a clean bill of health such that not a single hair on someones head would be ruffled - doncha just love consultancy -

regards

OMS

-------------------------
Failure is always an option
 09 November 2012 03:48 PM
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rocknroll

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LOL well. tis Friday.

Strange one though, trial by public forum is a bit like the ole witchfinder days, as an ex mediator a good one to get my teeth into, communication, training, supervision and the list goes on.

regards

-------------------------
"Take nothing but a picture,
leave nothing but footprints!"
-------------------------
"Oh! The drama of it all."
-------------------------
"You can throw all the philosophy you like at the problem, but at the end of the day it's just basic electrical theory!"
-------------------------
 09 November 2012 04:03 PM
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Avatar for OMS.
OMS

Posts: 19478
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Well for WIS and IGN systems it falls far short of the required technical standards - and clearly doesn't meet the design. There are probably at least the departures from BS761 mentioned above and the workmanship is crap by any measure in addition

I presume these are your own guys so how you handle the action will be covered by your guidelines and employment law

Regards

OMS

-------------------------
Failure is always an option
 09 November 2012 04:39 PM
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TeesdaleSpark

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You will probably get more joy out of looking in the Water Industry Mechanical and Electrical Standards (WIMES) than BS7671.
 09 November 2012 06:02 PM
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Fm

Posts: 650
Joined: 24 August 2011

I thought it was a wimes spec, with the earth tags on the tray!
That installation wont comply with 3.02 wimes electrical spec.
IET » Wiring and the regulations » Safe use of a compression gland

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