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Cable fastenings

me1899
Hi All


Got a job where a sparks is suggesting omitting mains cable tray and runnign armoured cables in a run of cold rolled steel channel.

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Steelwork seems to have nowhere to properly fasten cables whether cleats for bigger (70-95mm size) or tie wraps for smaller. Unless they want to wrap something around the whole thing?


Also some small screw ends popping which they are saying can be blunted.


The steel is only about a hundred wide and has some vertical struts going up from the middle so not really much useful space.


Surely there is a Reg that says you need to fasten cables properly even if they are laying inside a channel or tray? I just want to say no, put some containment in, but trying to find a reg that will put a stop to it.


Any thoughts on that?

  • 0
    if these are swa and flow and return currents are in the same armour, then the thing that occurs under high current faults with singles tearing themselves apart from their mountings is not going to apply. If you are looking at AWA singles then the fault currents will inform how strong any mounting needs to be.


    I do not like the sound of 'blunting' screw points,  but in terms of is it OK to lay a cable on a flat surface retained by gravity alone, from a regs perspective  yes it can be, and is very common in building voids..

    There are various spring clips that attach cables to metal work either with or without drilling, edge clips and spring nuts, or they may be intending to use small self-drill screws.

    It may or may not be OK - rather more info is needed. Equally if you are happy to pay for it and want some trunking, I cannot see from the info you have given why they would refuse.
  • 0
    If it's structural steel it might also be worth checking with the structural engineers about putting lots of even little holes in it...

       - Andy.
  • 0
    Tray is the way to go especially if more than one cable. How are exiting cables installed?
  • 0
    Thanks to all for replies.


    Colin, nothing has been installed as yet, but I have said that they can use that channel providing the install is neat, there is appropriate fastening and of course that the number of cables used is appropriate. That has been agreed with and they will be detailing how they will install so it can be reviewed and approved, including by the structural engineer as relevant.


    So basically a reasonable process will be followed on this and all the questions raised by you guys are going to be addressed.


    Sorry for slow reply, just been swamped after months of furlough.
  • 0
    That looks like the channel is facing down, so the cables will presumably lie on the flat upper surface, so what stops them falling off?
  • 0
    Hi Sparkingchip, I can confirm the channel is facing up - the base has a bit of an angle to it so it might look from a dodgy phone photo that it is facing down.


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