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  1. #1
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    Default How to attach Cabling trayway to an RSJ?

    Don't really know here to post this. Not really metalwork, not really electrical - if there was an electrical install forum I would have more choice


    I want to run some cable trays up near the roof, for 3 phase, air lines, et c. Usually these things are trapezium'd up (threaded rod, and strap or angle underneath). There is steel H-beam up there, trying to work out how to attach/suspend them (don't really want to drill into it, weld tabs on, et c).


    Current MacGyver'd hardware:
    IMG_0667.jpg



    Option 1:
    IMG_0664.jpg
    Well hidden in RSJ, but harder to install/remove lines, because;
    • not horizontal, so everything has to be cable tied in regularly
    • bar/straps get in the way for new cable runs. I would prefer one side of the tray mostly open



    Option 2:
    IMG_0665.jpg
    Maybe too much weight on bar/straps?



    Option 3, as per Option 2, but remove hoops and bolt trayway to straps. Would make top of tray completely open for new runs.



    Option 4:
    IMG_0666.jpg
    Horizontal, but half hidden in RSJ. No idea what hardware would need to be fabricated.




    Option 5, buy hangers to clamp under RSJ, like this:
    s-l200.jpg






    So, more experienced comrades, any suggestions?

  2. #2
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    Hi Nigel, I'd go with option 2. Not knowing the size of the RSJ and the cable tray, all my thoughts/sizing would be speculation, ie if the RSJ was 150mm wide and the cable tray 300.
    Instead of using flat bar, I'd use some angle iron probably 40 X 40 X 3 X 500 long, for appearances I'd cut the angle tray end at 45 degrees. On one end I'd bend a 90 degree flat bar hook probably 40 X 5 and weld it to the angle, so that you had enough room to slip over the edge of the RSJ, and down the angle. (Looking at your pics I'd say that it was about 12mm thick.) If the RSJ was 12mm, the welded leg would need to be about 60 mm overall length.
    Then I'd drill a hole to clamp it to the RSJ, then make some clamp blocks, using 40 X 12 and more 40 X 5, the 12mm about 40 mm long and the 5mm about 100 long and drill all for a 10 mm bolt, 20mm in from one end. OR use your existing clamp blocks. From the end of the angle with the hook your hole centre would need to be 150+20+3 (Fudge Factor) =173. The holes for the cable tray could be 6-8 mm as it's only to stop it from falling of the brackets.
    These brackets could be placed about 1.5 - 1.8M apart.
    HTH
    Kryn
    To grow old is mandatory, growing up is optional.

  3. #3
    BobL is online now Member: Blue and white apron brigade
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    What about this no bolt system??

    Screen Shot 2020-05-02 at 3.44.53 pm.png

  4. #4
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    https://www.ezystrut.com.au/products.../e1386/e1386h/

    Unistrut or EZYstrut is your friend. The clamp brackets aren’t poisonous expensive and neither is the unistrut. If you have more time than money you could make a copy.

    At work we invert the cable tray so it is open facing down, this does two things. It makes it easier to hang with less hardware required and it means that lazy installation practices can’t exist because in order to use the tray you have to tie cables in.

    Use good quality cable ties, not the $2shop white nylon ones. If you invert the tray it’s a good idea to use slightly wider than you normally would

  5. #5
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    Hi Nigel, Guys,

    I couldn't find a picture of the cable tray hook that I wanted, this link shows a picture of the sort of thing I was suggesting. You simply hammer the clip onto the "H" beam and support tray. The ones I seen have the hammer on part at both top and bottom but the bottom one is turned up

    https://www.discount-low-voltage.com...AT1224SM-jhook

    HTH.
    Best Regards:
    Baron J.

  6. #6
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    Default

    Kryn, thanks for your quick thoughts.


    Trayway is Burndy 150, so roughly 150mm wide. I think RSJs are 250x150 ish
    (probably 256 X 146 - 10.9MM FLANGE & 6.4MM WEB).


    Flat Bar is 25x8ish and Cadmium plated, but fairly soft. I have a lot of them.

    IMG_1104.jpg

    Angle Iron would be stronger, but I would have to buy it

  7. #7
    BobL is online now Member: Blue and white apron brigade
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    I would have recommended Unistrut but it's expensive and I guessed you already had the trays.

    Quote Originally Posted by nigelpearson View Post
    Angle Iron would be stronger, but I would have to buy it
    Maybe use AI for every third bracket?

  8. #8
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    Quote Originally Posted by racingtadpole View Post
    https://www.ezystrut.com.au/products.../e1386/e1386h/

    Unistrut or EZYstrut is your friend. The clamp brackets aren’t poisonous expensive and neither is the unistrut
    Used to work for Telstra, so have plenty of slotted UniStrut offcuts


    Upside down directly under the beam was my first thought (many months ago). Then I started looking for simple clips that would clamp onto the RSJ and the side of the trayway. Couldn't find any.

    Than I found the Option 5 hangers, and was enticed by the thought of minimal cable-tying!

    Being able to easily add or remove an air/coolant line, or other type of cable, does appeal highly at the moment.
    (I'm still planning locations for machinery et c)

  9. #9
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    Looks like a decent sort of shed that you've got, what size is it??????
    Kryn
    To grow old is mandatory, growing up is optional.

  10. #10
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    Quote Originally Posted by KBs PensNmore View Post
    Looks like a decent sort of shed that you've got, what size is it??????
    Kryn
    Strata industrial unit, about a mile from home. 130m2, plus 30m2 illegal mezzanine:

    IMG_0370.jpg

  11. #11
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    Nigel, the 25X8 would be plenty strong enough to support the cable tray, probably about the 1.2 - 1.5m apart should be fine.
    Nice size shed, what are you planning on doing in it, if you don't mind my asking???
    Kryn
    To grow old is mandatory, growing up is optional.

  12. #12
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    Hi Nigel, Guys,

    Nice large area ! It looks like there was a pit in there at one time. Has it been filled in or is it just covered ?
    Best Regards:
    Baron J.

  13. #13
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    The 25x8 should be strong enough, but drilling an 8mm hole in the middle for one clamp just seemed to create a weak spot. Might have been bending due to the clamp, I'll try some proper cast beam clamps. If I get/use some stronger angle as well, it should be appropriately over-engineered !


    I bought the space as a long-term investment. Was thinking sub-dividing (sharing with a small paying business) or using as a men's shed space. Currently half is unpaid storage, half as a little workshop as I acquire machinery. People occasionally bring me electronic repair, or mechanical/machining jobs that I play with.


    Space usually very full; other people's cars, other people's machinery...
    IMG_0327.jpgIMG_1354.jpg





    The mark on the floor is just where they didn't epoxy the whole space, because a machine was in the way. I think it was a truck frame alignment machine.





    ...damn thumbnail from when I chose the wrong file to attach, but can't get rid of it...
    Attached Images Attached Images

  14. #14
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    Default

    Quote Originally Posted by nigelpearson View Post
    Used to work for Telstra, so have plenty of slotted UniStrut offcuts
    I did 18 and a bit years with RCI/Network Development/NDC/Network Construction. Mostly with Commercial Works.
    Sadly 7yrs after leaving my supply of slotted channel was exhausted a few weeks back.

  15. #15
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    Quote Originally Posted by racingtadpole View Post
    I did 18 and a bit years with RCI/Network Development/NDC/Network Construction. Mostly with Commercial Works.
    Sadly 7yrs after leaving my supply of slotted channel was exhausted a few weeks back.


    I was 23 years in "Intelligent Networking Development." Software dev. team in Sydney. Hierarchy seemed to change every few years, but we were in NDC a decade or two ago. Was merged with TRL (Telstra Research Labs) for a while. Got some nice tools from that merger.

    My UniStrut offcuts were mostly scrounged from rubbish bins in exchanges - thrown out by you guys doing installs in a hurry!

    I actually have a lot more Ericsson U-bar than UniStrut?

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