Can SWA be run in the same metal trunking as singles?

[Mike Johnson]

I would very politely ask the COW what regulation does not allow this, they obviously know as they have stated it does not comply.

 

[twilks]

If I had more than one run of SWA I would be tempted to put up cable tray and clip to that. If the tray is vertical (parallel to wall, supported off by short lengths of strut, for example) then you need the occasional metal tie for fire support in addition to regular ties of any other sort.

If the SWA sits on top of a horizontal tray (so it can't fall if clips melt), for example supported on cantilever arms, or suspended from a roof, then standard cable ties are OK. Personally I would always use the black UV-tolerant type even indoors as sometimes it will get sunlight from windows, etc, and it saves me keeping multiple bags.

However, I also get the feeling this person is being difficult for no obvious reason. I would be tempted to present your suggestions for alternatives in writing (e.g. email) and make sure they respond also in writing just to cover yourself.

Incidentally, when you said trunking I was thinking of the metal stuff, 50x50mm upwards, not plastic. Can you confirm the type?

100x100 metal trunking, only 1 SWA to run. After SWA goes in with the other circuits.we are at approx 10% capacity

 

[littlespark]

You’re still going to have to gland the swa into the trunking somehow, even leaving armour on.

I have to agree that there is no valid reason that it can’t be clipped surface. It’s perfectly ok in every other building.

 

[twilks]

You’re still going to have to gland the swa into the trunking somehow, even leaving armour on.

I have to agree that there is no valid reason that it can’t be clipped surface. It’s perfectly ok in every other building.

The beginning of the swa run is internal (where the trunking is), then runs externally to an outbuilding to upgrade a feed there.

There seems to be no logical reason to a lot of his requests

 

[twilks]

Just one other thought, how would the SWA armour be connected?
I can see both sides of this, whilst I also cannot see a reason why it is Non compliant, it will take up more room in the trunking than the equivalent in singles?!
Personally I would if in trunking be using singles for ease and space saving.
When they ask you back again at a later date to install more circuits you will either be wishing for more space or thinking, glad I left some spare capacity in that trunking!
Just my 2pennies worth.
Sy

Entry and exit to trunking will be 32mm metal compression gland, there is then a 30m run beyond trunking to the next dB that the swa continues to.

100x100 trunking with, at a maximum, 10 singles conductors (2.5, 4 and 6mm) so trunking will be approx 10% capacity with SWA installed

 

[Mike Johnson]

Ensure when you ask the question which regulation if does not comply with you have a copy available to ask them to point it out, too easy to say I just know it does not comply.

 

[littlespark]

You keep saying its only going to be 10% full with the swa in.... like its a reasoning to do it the way he's suggesting....but if that's the case, there should be some paperwork with the design saying something like... "have oversized the trunking to accommodate the SWA cable"
A conscious decision to not do it the way its done everywhere else.
100mm square does seem oversized for what you say is going in.... which does suggest they think there will be more added in the future.


OK, it will save some time, not having to separately clip the swa along the route, and maybe its an aesthetic decision... One square metal trunking might look neat against the wall, but not a black cable with tray, or cleats alongside.


"doesn't comply" is an absolute cop out, but one that is easily debunked if you've got the book there.

 

[twilks]

You keep saying its only going to be 10% full with the swa in.... like its a reasoning to do it the way he's suggesting....but if that's the case, there should be some paperwork with the design saying something like... "have oversized the trunking to accommodate the SWA cable"
A conscious decision to not do it the way its done everywhere else.
100mm square does seem oversized for what you say is going in.... which does suggest they think there will be more added in the future.


OK, it will save some time, not having to separately clip the swa along the route, and maybe its an aesthetic decision... One square metal trunking might look neat against the wall, but not a black cable with tray, or cleats alongside.


"doesn't comply" is an absolute cop out, but one that is easily debunked if you've got the book there.

He hasn't suggested a way at all, says that's our job. Drawings only specify location of accessories and what circuit.

He has said no to clipped direct because 'it will look ---- ' his words. Also a no to SWA in the trunking with singles. Time to email a superior imo

 

[Mike Johnson]

He has said no to clipped direct because 'it will look ---- ' his words. Also a no to SWA in the trunking with singles. Time to email a superior imo

So it's the aesthetics he objects too, not something in the Regulations?

 

[Mike Johnson]

Yes, complete SWA. We have installed trunking for an installation with 2.5mm, 4mm and 6 mm singles.

We've now been asked to run a 10mm swa for a supply to a new dB and a lot of the trunking is along this route.

Reading the second sentence it would tend to indicate this is a change to the specification, do you have a COW Site Instruction to carry out this extra works, if so get them to specify how they wish it to be done, just don't do it until they instruct you, perfectly legitimate not to carry out the work until you are satisfied with the instruction as it's an extra, have you priced it or is it on day works at your enhanced rate?

 

[twilks]

So it's the aesthetics he objects too, not something in the Regulations?

Aesthetics for clipped direct, and just says swa can't be run in the same trunking as singles so I can only assume he means that regs prohibit it.

Imo this is something for the mep to deal with and is above my role

 

[pc1966]

Aesthetics for clipped direct, and just says swa can't be run in the same trunking as singles so I can only assume he means that regs prohibit it.

If it is aesthetics they are complaining about then it is unlikely cable tray will pass muster. However, I have often seen tray near the ceiling in places and most folks just don't notice it.

The only regulation or instruction that I can think of that might make SWA in 100x100 trunking an issue is bend radius if it has to enter/exit through the side. 10mm 4C SWA is about 20mm or so diameter, so the bend radius would normally be about 8 times that (check manufacturer's specifications here) and so you are looking at 160mm radius, so a 90 deg bend won't fit in 100mm trunking.

Taking it out end caps so practically no bend, etc, is perfectly fine, and as you suggested compression glands would serve well to keep things in place and preserve a decent IP rating where a 25mm grommet might not.

Stripping a long length of SWA to have the inner cores (probably kept in the inner insulating sheath) in the trunking is just not sane or practical to do. You could use a SWA gland through the trunking to an adaptable box inside, and there use some crimps or similar to connect the 10mm to some 10mm singles for the run, etc, plus a copper CPC from the banjos or earthing nuts just to be sure of armour earth integrity, but it means added joints which usually you want to avoid. Would it only be needed at one end, if this trunking goes direct to some main DB?

Imo this is something for the mep to deal with and is above my role

Indeed, but put down you ideas and suggestions to your superior in an email or so so they have a solid case to take up with the COW to get a decision.

 

[littlespark]

I've been following the wrong thing here...



You say the COW doesn't want it clipped direct, but he also doesn't want it run in the trunking??


How the hell does he want you to get it from A to B then? Some of that magic wireless power?

A second, empty trunking, just to hide the swa in?

A different route so its not seen?

 

[twilks]

Reading the second sentence it would tend to indicate this is a change to the specification, do you have a COW Site Instruction to carry out this extra works, if so get them to specify how they wish it to be done, just don't do it until they instruct you, perfectly legitimate not to carry out the work until you are satisfied with the instruction as it's an extra, have you priced it or is it on day works at your enhanced rate?

I've been following the wrong thing here...



You say the COW doesn't want it clipped direct, but he also doesn't want it run in the trunking??


How the hell does he want you to get it from A to B then? Some of that magic wireless power?

A second, empty trunking, just to hide the swa in?

A different route so its not seen?

I honestly don't know, the area it's run in is a welders workshops and a carpenters workshop, with 4 meter tall ceilings with trunking at 3.7m and the ability to clip direct above or below trunking. These aren't aesthetically pleasing rooms as you can imagine.



Very tempted to walk away right now it's absolutely ridiculous

 

[westward10]

For some reason they are being awkward with you just pass it on to your superior.