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Topic Title: TRUNKING
Topic Summary: REGULATION 521.10.1
Created On: 20 December 2012 06:08 PM
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 20 December 2012 06:08 PM
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John Peckham

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I wonder why the new requirement in the 17th Edition contained in 521.10.1 for trunking systems to have an IP4X rating? They should not contain exposed live parts, but they do often, but they are connected to enclosures that do contain live parts where on accessible sides you can have an IP2X rating. Mind you I don't think the requirement is widely observed even on new jobs.

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John Peckham

http://www.astutetechnicalservices.co.uk/
 20 December 2012 07:06 PM
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slittle

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The ECA technical team raised this not very long ago John. Members were asked to contribute to a lobbying session as it was felt IP4X wasn't practical.

Apparently the response from the IET was along the lines of it is and you will...... So that will be a deviation to record on the next EIC then

Stu
 20 December 2012 07:10 PM
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Legh

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John,
Its not that new. It was in the 2008 edition.
It basically means that bits of carp can't get into the top surface which as you've pointed out is not always that secure.

Wait till you get to do some I&T on food manufacturer's trunking. One company weld their lids on to stop ingress of more or less any forign body due to the need for cleaning !

Legh

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 20 December 2012 07:20 PM
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GB

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Probably in there because the manufacturers asked for it!!!
 20 December 2012 07:27 PM
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OMS

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So that will be a deviation to record on the next EIC then


Aren't you guys just fitting the cover clips then ? - from memory, these will give both IP4X and IPXXD - certainly the Salamander range from Legrand will - I think Newlec have a not dissimilar product as well

regards

OMS

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Failure is always an option
 20 December 2012 08:03 PM
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Jobbo

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Trunking is manufactured to IP33 and since this regulation was introduced, covers were quickly produced as OMS states above. Do they get fitted on site? Not on any I've seen

Do I record this on an EICR, well it's in my summary for sure.

Anyone who has worked on the tools metal munching, will know that to provide a containment system at IP4X is pretty difficult indeed
 20 December 2012 08:40 PM
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OMS

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You wouldn't get a fag paper through my site cut joints Jobbo, let alone a 1.0mm dia probe

for the good jobs there's always welding

Regards

OMS

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Failure is always an option
 20 December 2012 09:35 PM
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Legh

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Agreed, all the stuff we did fitted together without gaps although I never did the fag paper test on every joint, nevertheless, i have seen some pretty poor installations with joining plate,screws and lids missing.

Legh

-------------------------
Why do we need Vernier Calipers when we have container ships?

http://www.leghrichardson.co.uk

"Science has overcome time and space. Well, Harvey has overcome not only time and space - but any objections."
 21 December 2012 08:02 AM
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dickllewellyn

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Welding trunking eh. I remember in my early days fitting out a blacksmiths workshop. The blacksmith noticed me cutting and forming my own bends and sets rather than using pre fabricated, and suggested he could help, and we could weld the joints rather than nuts and bolts. As we set up the first weld, he donned his visor while I looked away, with strict instructions to hold my breath. That was when he explained the little whispy bits floating in the air after welding were cyanide formed from welding galv steel!

I left that job in the evening with a feeling I was wearing a hat when I knew I wasn't!

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Richard (Dick)

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 21 December 2012 10:25 AM
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OMS

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I've welded lots of it - both with and without galv finish and with gas and electric arc - although we used to use face masks with air blowers or air feed lines connected or sections were "pre-fabed" in welding booths with LEV. Grinding back the galv finish was always a good plan

The symptoms of welding galv was know as "Galv Flu" or metal fume fever- you used to get fee milk to drink !!

It's not good stuff, that's for sure

Regards

OMS

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 21 December 2012 11:24 AM
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tomgunn

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I thought that you couldnt make up bends as I used to do all of the time - as only mechanical bends are allowed nowadays? I always worry about the 'air factor' when I am using a lump of 3" x 2" bit of wood to hammer in the latest 16mm 3p&n supply so that I can get the lid to fit back on using the obvious peices of wood to hold them back - worry worry a?

Tom

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 21 December 2012 02:53 PM
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spinlondon

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Regulation 521.10.1 appears to conflict with 416.2.2.
The wording of 512.10.1 suggests that the IP4X rating applies to all surfaces, whereas 416.2.2 only requires that the top horizontal surface be IP4X.
How does this relate to wiring systems where surface trunking is used to supply surface mounted sockets and accessories?
Seems a bit odd to require such a high degree of protection for the containment, then to require a lower degree of protection at the point of utilisation.
 21 December 2012 03:38 PM
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OMS

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Seems a bit odd to require such a high degree of protection for the containment, then to require a lower degree of protection at the point of utilisation.


Would that be because people are more wary of inserting objects at points of utilization but less so for containment because they may not recognise what it is and thus not appreciate the risk ?

regards

OMS

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 21 December 2012 04:00 PM
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spinlondon

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Perhaps people are more wary of inserting objects at points of utilisation.
However it still seems odd, that the Regulations allow part of the containment system which is enclosing uninsulated conductive parts to be rated at IP2X, then insists that the part of the containment system which encloses insulated conductive parts be provided with an enclosure rated at IP4X.

For instance with a CU, if the cables are bottom entry, the rating is required to be IP2X, however if a length of trunking is attached to the bottom of the CU, and the cables enter and pass through the trunking into the CU, the rating is required to be IP4X.
 21 December 2012 04:06 PM
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OMS

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I don't disagree Spin - I was just thinking aloud as to what JPEL 64 had in mind when they drafted the reg

Regards

OMS

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 21 December 2012 04:51 PM
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spinlondon

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I guess it's one of those areas where engineering judgment comes into play.
Perhaps 521.10.1 will get amended, to bring it in line with 416.2.2?
 21 December 2012 05:08 PM
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Legh

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On a slightly different track.
I remember that surface mounted compartmentalized alcove trunking and wall trunking was work always given to those who who had good quality bench fitting skills.
The monkeys were left with everything else.

Not to say that good quality craftsmanship shouldn't apply to all areas of electrical work. But, as some saw it, needs must when your on a tight schedule.

and if the work was really duff then, as I remember, you were required to walk....

Legh

Legh

-------------------------
Why do we need Vernier Calipers when we have container ships?

http://www.leghrichardson.co.uk

"Science has overcome time and space. Well, Harvey has overcome not only time and space - but any objections."
 23 December 2012 11:15 PM
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AJJewsbury

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I was just thinking aloud as to what JPEL 64 had in mind when they drafted the reg

Could it have been 'copied across' from HD 60364 rather than being a JPEL/64 invention?
- Andy.
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