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

[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.

 

[Mike Johnson]

Just give him in writing an estimate of how much it will cost to hide all the SWA to his satisfaction and copy it to the client, I think there would be some very embarrassed face's at the next project meeting.

Thinking further, 4M ceiling with the trunking at 3.7M which means working off MWEP or ladders, has the Health and Safety Co-ordinator been involved in this? their main function after all is the Safety of the workforce, easier to do if they do not have to leave the ground, is it possible to run the trunking around the walls?

 

[twilks]

Just give him in writing an estimate of how much it will cost to hide all the SWA to his satisfaction and copy it to the client, I think there would be some very embarrassed face's at the next project meeting.

Thinking further, 4M ceiling with the trunking at 3.7M which means working off MWEP or ladders, has the Health and Safety Co-ordinator been involved in this? their main function after all is the Safety of the workforce, easier to do if they do not have to leave the ground, is it possible to run the trunking around the walls?

We have a mobile tower which is plenty safe enough. It's been decided that we run 50mm tray below the trunking which is fine. Leave the bosses to sort out variations from scope

 

[Mike Johnson]

Just a vagary to throw into the pot when they are being awkward.

The most common accidents on site's are falls from height, if the work can be done at low level that is preferable than working off a tower that you have to access probably without a harness and up a ladder, unless it's a professional tower with internal access, kick boards at all levels and double rails, getting your tools and equipment to the top level also has to have consideration, not in a bucket pulled up on a rope, or worse carried up by you whilst climbing the ladder, who supplies the access equipment, if it's the site these things if relevant should be brought to the attention of the COW for them to sort out.

 

[pc1966]

I would add that with 50mm trunking you need to be aware of bend radius of the SWA if the run is not straight. You might need to use a pair of 45 deg bends, etc, to get something sane. Also some suppliers have a very "square" 90 deg bend and others (like Unitrunk) have a bit more curve allowed.

 

[twilks]

I would add that with 50mm trunking you need to be aware of bend radius of the SWA if the run is not straight. You might need to use a pair of 45 deg bends, etc, to get something sane. Also some suppliers have a very "square" 90 deg bend and others (like Unitrunk) have a bit more curve allowed.

We're fabricating ourselves due to lack of access to materials. I believe 4 core 10mm has a ten fold diameter for bend radius so definitely need to be careful we.dont fall foul of that

 

[pc1966]

We're fabricating ourselves due to lack of access to materials.

WTF???

I believe 4 core 10mm has a ten fold diameter for bend radius so definitely need to be careful we.dont fall foul of that

If you have some cable tray you ought to be able to make a gradual 90-deg bend by cutting V-shaped sections out and bending it in the a fan-shape. You will need some short links to join up the inner edges that you cut away to give it some strength though.

 

[twilks]

WTF???

If you have some cable tray you ought to be able to make a gradual 90-deg bend by cutting V-shaped sections out and bending it in the a fan-shape. You will need some short links to join up the inner edges that you cut away to give it some strength though.

We're abroad and it takes a couple of weeks and a lot of money to get anything here, materials were ordered by the office.

 

[pc1966]

We're abroad and it takes a couple of weeks and a lot of money to get anything here, materials were ordered by the office.

Ah, that makes some sense.

 

[Simon47]

We're abroad and it takes a couple of weeks and a lot of money to get anything here

That's something that strikes me watching some of those North American series (Ice Road Truckers, Wikd Akaska, and the like. We're so used to just popping to the wholesalers to get common stuff from stock, or next day, or withing a few days if it's a special order. And planning on the basis that if we forget something, it's no big problem. Not just electrical, but for other stuff - e.g. I know I can pop round and pick up a bag of cement if I run out.
The idea that we have to accurately work out our materials a year in advance, have them delivered during a short window, and if we get it wrong then we're screwed is ... quite a mindset shift.

 

[Mike Johnson]

It's all to do with land area, if you look at any house in rural France, which is vast in comparison to the UK, you will see that nearly every house has a trailer sitting somewhere in the property, this is due to obviously to pick up supplies, but also due to the vast amount that companies charge for delivery.