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

[twilks]

I have checked the regs and can't find anything to say this can't be done. Although I'm worried about cable movement in the case of short circuit damaging singles in the trunking

 

[pc1966]

You are fine with that. Of course usual good installation practice needed, but SWA won't move that much unless you are looking at really high energy faults, and more so for sets of AWA singles making up a really high current 3P set.

 

[littlespark]

do you mean complete SWA? with the armour? or glanded into the trunking, and the inner cores within trunking?


"Singles" cable has a slightly tougher insulation than something like the inner basic insulation of t&e... Can take a bit of rough treatment no problem.

 

[twilks]

do you mean complete SWA? with the armour? or glanded into the trunking, and the inner cores within trunking?


"Singles" cable has a slightly tougher insulation than something like the inner basic insulation of t&e... Can take a bit of rough treatment no problem.

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.

 

[twilks]

You are fine with that. Of course usual good installation practice needed, but SWA won't move that much unless you are looking at really high energy faults, and more so for sets of AWA singles making up a really high current 3P set.

Thanks for the reply, the fault current will be 10Ka (theoretical maximum at origin) for the swa as we are right by the site intake.

We have at a maximum 10 single conductors (2.5, 4 and 6mm) at the busiest points in the trunking. All single phase including SWA. I suggested it to the clerk of works and he said absolutely not allowed.

I disagreed and have since been searching high and low for a regulation that prohibits this.

 

[nicebutdim]

I can think of reasons why the clerk of works might not want SWA eating up space in trunking, but none that involve wiring regulations.

 

[twilks]

I can think of reasons why the clerk of works might not want SWA eating up space in trunking, but none that involve wiring regulations.

Thank you! We have a massive amount of space left on the trunking. A maximum of 10% capacity before the 10mm SWA goes in.

 

[littlespark]

Possible future plans require the space in the trunking?

Whats wrong with running the SWA alongside the trunking? Its mechanically protected already. Or, as i said earlier, gland it in and run it through without the armour.

 

[nicebutdim]

Clerk of works will have the final say. I wouldn't waste time arguing with him and would instead ask how he'd like it to be routed - limitations with regard to support might actually result in him having a change of mind. Do whatever he wants and invoice accordingly.

 

[twilks]

Possible future plans require the space in the trunking?

Whats wrong with running the SWA alongside the trunking? Its mechanically protected already. Or, as i said earlier, gland it in and run it through without the armour.

For some reason he doesn't like it clipped direct. Unfortunately it's at the beginning of a 70m run so glanding into trunk is not an option. Clerk also refuses to allow us to clip direct.

I was only really looking for 2nd opinions on this matter as he has highlighted my suggestion to run in the trunking to the client and has questioned my competency

 

[twilks]

Clerk of works will have the final say. I wouldn't waste time arguing with him and would instead ask how he'd like it to be routed - limitations with regard to support might actually result in him having a change of mind. Do whatever he wants and invoice accordingly.

He has refused to make suggestions on how to actually do it as he states 'that's not his job'.

I wanted to triple check that this is in fact acceptable as he has reported my suggestion to his superiors.

Thank you for taking the time to reply!

 

[SparkySy]

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

 

[nicebutdim]

He has refused to make suggestions on how to actually do it as he states 'that's not his job'.

You've suggested two methods of installation which he has rejected and neither for any regulatory reason and this is something I'd make very clear to him - I'd contend that it's very much his job to decide how the cable is run, unless the client provides a spec.

 

[westward10]

Is it not possible to use singles in trunking. Sounds like he for some reason has an issue with you and will find a problem no matter what you suggest.

 

[pc1966]

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?

 

[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