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Looking for some advice if anyone can help.

I've been asked to install sockets in a new build business unit. The company deals with software imaging - lots of computing power but no machinery, tools, etc.

The place is pretty much a standard build with a number of heavyweight vertical RSJ's cross-hatched with U-shaped, mild steel beams onto which a potential plasterboard wall could be fixed. The client is leaving this open, though, so I was hoping to hole-cut through the steel beams and run a 20mm plastic conduit through from one end to the other in an L-shape from the CU on one wall a total length of around 20m.

I'm running a radial circuit for four twin sockets as they are all being placed on this one run. Trouble is, the regs say that rigid plastic conduit has to be supported at 1.5m intervals for a horizontal run, and there's approx. 2m space between these. So, i'm considering fixing a 3x1/2" wooden plate along the length of the wall on top of the steel uprights and then fixing the conduit to that. Steel conduit or tray are options, but I'm trying to keep the price as keen as I can. Can anyone suggest another method?

Thanks
 
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Jay Sparks

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Mentor
Arms
Without seeing the install, I think useing a piece wood for the fixings sounds ok. Although, I dont think it would be a big problem if the fixings were every 2m instead of 1.5m.

Jay
 
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  • #3
Without seeing the install, I think useing a piece wood for the fixings sounds ok. Although, I dont think it would be a big problem if the fixings were every 2m instead of 1.5m.

Jay
Cheers, Jay.

I'm just a bit concerned that the conduit will be hanging in open air inbetween the uprights; wouldn't be so bad if they were going to be covered in plasterboard, but the customer is leaving the wall open, so there is always the chance that some gormless individual will use the conduit to support themselves while they tie their shoes :-/

Just thought there would be another method?
 
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  • #5
use steel trunking or steel conduit. and i'd be wary of drilling through structural steel.
That was another concern, Telectrix, but on looking at the structure, the steel isn't really supporting anything; it appears only to provide a support for the fixing of the outer (tin plate) walls, and the (potential) internal plasterboard / composition walls.

On the face of it, though, I think I'll quote for the wooden plate; it'll give me good fixings for both the conduit and the sockets.
 

telectrix

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Mentor
Arms
Esteemed
doesn't the steel support the roof girders and hence the roof?
 
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  • #7
It doesn't appear so, Telectrix; The main RSJ's are bolted to cross members which the roof is attached too, the internal steel work is definitely not capable of taking that sort of weight.
 

tigerpaul

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Arms
Don't forget, the plastic conduits will be heavier with the cables in them and will sag down... Not a good look really.
I'd suggest steel, keep it tidy, it won't flop about when and if it ever gets cleaned either.
 

tigerpaul

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Arms
Also, get clarification on drilling the steel, you don't want to ruin the integrity of the structure.

What about using caddy clips to hold the steel conduit up?
 
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  • #12
Don't forget, the plastic conduits will be heavier with the cables in them and will sag down... Not a good look really.
I'd suggest steel, keep it tidy, it won't flop about when and if it ever gets cleaned either.
Only running 2 x 4mm singles and a cpc but, yeah, it's not a good look is it - and certainly not going to be rigid :-(
 

Des 56

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Arms
Esteemed
What do you suggest, Des?
Almost impossible to say without seeing the place,but if conduit can't be supported,therefore ditto tray
Swa on the floor, or conduit dressed around the pillars,metal trunking will give its own support to an extent,that has sometimes been my own decisions occasionally when some self support was needed
 
Id' certainly go with galv tube, Plastic may look ok now but give it ten years? The spacings in BS7671 are the maximum spacings and way, I would say plastic should be supported more like every 3' in honesty.
 
G

Guest111

The beams may not be holding the roof up but may be to stop the structure splaying outwards,either check that its acceptable to drill holes in it (25mm for 20mm conduit) or get the owner to give you something in writing saying that they are happy with it done that way otherwise it may end up costing you a lot more than you make,be carefull
 
The beams may not be holding the roof up but may be to stop the structure splaying outwards,either check that its acceptable to drill holes in it (25mm for 20mm conduit) or get the owner to give you something in writing saying that they are happy with it done that way otherwise it may end up costing you a lot more than you make,be carefull
Indeed, most big jobs I've been on specify that you cannot remove metal from an rsj, however you can drill, tap and bolt to them.
 
E

Engineer54

Indeed, most big jobs I've been on specify that you cannot remove metal from an rsj, however you can drill, tap and bolt to them.
That specification clause normally comes with a proviso, '' Unless otherwise agreed and authorized in writing by the project 'Structural Engineer''. 9 times out of 10, i've never had a problem with getting authorisation, the cluase is there to stop the numbties chopping lumps out of structural steelwork etc.... lol!!
 
That cluse if for the minions like me engineer, also saves the apprentice going through 3x 4" holesaw tring to go that bl**dy ducting through that girder - it was the easiest we thought! lol

On a serious note though we have rarely had issue drilling RSJ's with permission, only once or twice on older refit jobs where they have already been peppererd!
 
  • Thread Starter Thread Starter
  • #20
The very fact that the plastic conduit is running at a touchable height means I'm going to fix it to a plate; the gaps are just too wide and the conduit to flexible for me to be happy with it only being supported by the steel framework.

I also take on board the concerns re - hole-cutting the structure. As Engineer54 suggests, I don't think there would be a problem drilling the steelwork - it's actually pretty pliable, and I think it's only there to fix the plasterboard wall too - but, in future, I'll ask permission first; good advice.

Thanks, all, for your input :)
 
Looking for some advice if anyone can help.

I've been asked to install sockets in a new build business unit. The company deals with software imaging - lots of computing power but no machinery, tools, etc.

The place is pretty much a standard build with a number of heavyweight vertical RSJ's cross-hatched with U-shaped, mild steel beams onto which a potential plasterboard wall could be fixed. The client is leaving this open, though, so I was hoping to hole-cut through the steel beams and run a 20mm plastic conduit through from one end to the other in an L-shape from the CU on one wall a total length of around 20m.

I'm running a radial circuit for four twin sockets as they are all being placed on this one run. Trouble is, the regs say that rigid plastic conduit has to be supported at 1.5m intervals for a horizontal run, and there's approx. 2m space between these. So, i'm considering fixing a 3x1/2" wooden plate along the length of the wall on top of the steel uprights and then fixing the conduit to that. Steel conduit or tray are options, but I'm trying to keep the price as keen as I can. Can anyone suggest another method?

Thanks
Must be a new regulation that as it is not in mine

Also as you say that this radial is going to be provided for IT equipment do you think that your radial design of 4mm conductors and I assume that is a 4mm CPC and not perhaps even a 2.5mm is perhaps the best
 
  • Thread Starter Thread Starter
  • #22
Must be a new regulation that as it is not in mine

Also as you say that this radial is going to be provided for IT equipment do you think that your radial design of 4mm conductors and I assume that is a 4mm CPC and not perhaps even a 2.5mm is perhaps the best
I was intending to run 4mm singles, Malcolm. As for the supports, I'm quoting Table D3 in the OSG.
 
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