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Topic Title: Space Factor - Conduit, trunking
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Created On: 01 April 2008 03:41 PM
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 01 April 2008 03:41 PM
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mohussain

Posts: 15
Joined: 29 January 2008

Hi all,

If trunking or conduit clearly does not meet the space factor as set out in the Regs, handbook and wiring is tight - what would you do?

- re-install and therefore re-wire?

- turn a blind eye?

I come across so many instances (in fact all) where there is no space factor, as I am responsible now for putting my name on test sheets, I'm not sure what to do!

Any advice greatly appreciated.

Mo.
 01 April 2008 03:51 PM
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OMS

Posts: 19471
Joined: 23 March 2004

Well, which regulation being breached would be a starting point.

OMS

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Failure is always an option
 01 April 2008 04:06 PM
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mohussain

Posts: 15
Joined: 29 January 2008

Hi,

see regs book

522-08-01
522-08-02
522-08-03

See also Page 109-114 On site guide.

I'm more concerned about circuits being added which would obviuosly affect the grouping factor.

- Or am I looking into it to deeply.


Mo,.
 01 April 2008 04:15 PM
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OMS

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Ok - space factors are generally based on ease of drawing in of a wiring system and avoiding damage to cabling(522-08-010, and for rewiring (522-08-02).

Space factors make no account of grouping of circuits.

If you are considering adding circuits to existing conduit then I agree that is a recipie for disaster but really a descision for the designer of the circuit to address - unless you are signing in that capacity ?

Would you care to give an example of the number of conductors, size and containment system that you have come across that gives rise to concerns.


Regards

OMS

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Failure is always an option
 01 April 2008 06:32 PM
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Backintime

Posts: 282
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Can you not air-conditioning the trunkings and conduits?
 02 April 2008 11:42 AM
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mohussain

Posts: 15
Joined: 29 January 2008

Hi,

You come across this all the time.

Trunking packed full of cable - no space at all.

Conduit - full of cable - no space at all.

I've seen this at brand new installatiosn and older ones.

Thats why I was asking the question -

- Air conditioning is the way forward then :-)

Mo.
 02 April 2008 11:51 AM
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mohussain

Posts: 15
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Just to add to the above:

I was more concerned about older installations where trunking is full due to new circuit additions.

For a proper inspection and test - in the absence of information - I would have to check the circuits design meets the regs to grouping, etc - to ensure a correct condutor size is used.

But if say - the trunking is nearly full - should it be a recommendation or a action to upgrade to a bigger size?

thanks for any replies,

Mo.
 02 April 2008 12:08 PM
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Backintime

Posts: 282
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Since you are looking at existing installations, perhaps it's worth monitoring the rise and fall of temperatures of the overcrowded sections over a period of time. You then have the necessary information to make an informed decision - I mean recommendation. Give the client a quote, when they agree to the extra work buy us a round of black gold.

Edited: 02 April 2008 at 12:09 PM by Backintime
 02 April 2008 03:49 PM
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tomgunn

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Its all very well quoting the regs as per the space factor... get real and work on site... 'space factor'? hahaha... in the real world we use a block of wood and a hammer sometimes... oh cant wait to hear that thats very naughty and sooo wrong... but like most rules IN LIFE... you cant always comply.

Makes me laugh when told 'you cant run two T&E's in a single hiat clip coz of heat'... hahaha look in most trunking and you will see many T&E's laying in the bottom close together so what can you do / say?

-------------------------
Tom .... ( The TERMINATOR ).

handyTRADESMAN ... haha

Castle Builders

Why did Nick Clegg cross the road? Because he said he wouldn't!

I can resist anything..... except temptation! ( Karl Gunn ).

Edited: 02 April 2008 at 03:52 PM by tomgunn
 02 April 2008 06:07 PM
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perspicacious

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"Makes me laugh when told 'you cant run two T&E's in a single hiat clip coz of heat'... hahaha look in most trunking and you will see many T&E's laying in the bottom close together so what can you do / say?"

I think that someone was taking the micky out of you Tom.

The clip is being used outside the scope of its standard.

Regards

BOD
 02 April 2008 06:28 PM
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Backintime

Posts: 282
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Originally posted by: tomgunn

Its all very well ...
... but like most rules IN LIFE... you cant always comply.


It's all very well to say this to her - the BOSS, but in electrical wirings, you have to comply with the current edition of the Wiring Reg!

Edited: 02 April 2008 at 06:29 PM by Backintime
 02 April 2008 10:09 PM
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industryspark

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i have to agree with tomgunn, ive seen and look after installations where space and trunking factors have been ignored. now im not saying i would be happy adding more circuits/cables to these but likewise i wouldnt shut down half a factory just because there is a few too many cables in a bit of trunking.

im all for complying with the regs but sometimes you have got to make a judgement, in this situation if you can provide evidence as to why you think it wont be a problem (i.e,study temperature at various times or survey the loading over different time periods)and your confident in your analysis then i cant see a problem.

of course if a chance arises to correct it then by all means do so but in the real world cost/production dont always allow it.
 03 April 2008 01:03 AM
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tomgunn

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perspicacious & backintime.. I really did know that I would be up for some criticism about what I had said... I was actually using it as a bait to see who would 'bite' and so far its you two... so lets take Mr. perspicacious. My mind BOGGLES to be honest that we could even be debating as to what or not, hiat clips should be used for... I only learnt a year ago that you are not supposed to use one clip for two cables.... a 2.5mm clip will fit very nicely over two 1.5mm T&E cables so if its not the heat problem but as you say its being used outside its purpose has to be too much like the nanny state we now have to live... I would have thought that there would be more pressing regs that need attention... like... the most hated change in the history of electrical contracting and my personal hate... the colour change... so whats more dangerous.... the change of our colour system, ( read many posts.... "what colours shall I use for the 3 core SWA that I am installing?" .... time after time after time!!!! ), and people are actually concerned that a hiat clip is not being used appropriately??? do you know what....? nah... I leave that one there for the time being....

Mr. Backintime... I cant say that to 'her' because she's dead! AND.... like 'her' the only thing in life that you have to do is... die!! Most people are weak and just take orders... oh dear the NON STATUTARY regs say we MUST do this and MUST do that... I ask this question... why?

I take it that you are a long served electrician then? I will assume that you have worked on hundreds, ( literally as I have ), of industrial works over the years...? so how many new circuits have you had to run in old trunking... I have seen, even after I had warned a couple of electrical contractors that they were installing the wrong size trunking, packed out trunking no matter what the size... and you're asked to run a couple more 3 phase circuits in the old trunking... you take off the lid and wow! Its packed out.... long runs... what are you going to say? Cant do that guv.... aint enough room! They'll get someone else to do what 1000's of sparks do regularly... now look!!! I am not saying this is right but thats what happens out there in the real world and it all boils down to one factor.... MONEY!

-------------------------
Tom .... ( The TERMINATOR ).

handyTRADESMAN ... haha

Castle Builders

Why did Nick Clegg cross the road? Because he said he wouldn't!

I can resist anything..... except temptation! ( Karl Gunn ).

Edited: 03 April 2008 at 01:11 AM by tomgunn
 03 April 2008 10:02 AM
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Backintime

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Tom

On my way to work, there is a stretch of road where a bus lane has been assigned. Everyday I see many motorists simply ignore the bus lane restriction and use it to take the short cut. They were all happy and be ahead of me and others that were stucked behind a line of cars.

One day, a few of the cars in the queqe saw this and pulled out to join them. Unknown to them, there were traffic policemen hidden around the corner and told them to stop and issued them with fines and endorsement points.

Everyone knows there was very little danger that the motorists could have caused by them using the bus lane - neither if you overfill a trunking above the space factor if no overheating of cables should occur (it's not meant to be a comparison). The rules (either traffic or BS7671) are there for a reason, to ensure the majority of us conform to a good set of orderly way of doing things. So if I conform to the space factor or apply the correct rating factors to the cables when I install my wirings, by not taking chances, I done and dusted the job, sleep well and get up in the morning to do another job. Life too short to introduce complications into the jobs. If my client does not like me to put in a separate wiring route, they can get someone else to do what they want, I will work on another job instead.
 03 April 2008 12:00 PM
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tomgunn

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I know.. I know that you are right!! No really.. but theres too much nanny state going on.. I know you will argue the point of fire in trunking, ( I for one have never seen it... or even overheated cables and I have seen miles of the stuff ), and air factor but thats not the real world... sitting in a nice air conditioned room making up really stupid AND dangerous alterations to the wiring regs is also stupid, ( eeer Backintime... every fancied being a copper? Just wondered ... thats all.... bit like my mates at golf I suppose... they keep saying... why dont you take up tennis? ).

-------------------------
Tom .... ( The TERMINATOR ).

handyTRADESMAN ... haha

Castle Builders

Why did Nick Clegg cross the road? Because he said he wouldn't!

I can resist anything..... except temptation! ( Karl Gunn ).

Edited: 03 April 2008 at 12:02 PM by tomgunn
 03 April 2008 01:12 PM
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mohussain

Posts: 15
Joined: 29 January 2008

Great Stuff


Many, many thanks for replies / discussion / advice.

I'm off to take up TENNIS


Take care all,

Mo.
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