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Bad experience of Screwfix Tower trunking - how's it work?

Discussion in 'Electrics UK' started by PaulUszak, 7 Mar 2017.

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  1. PaulUszak

    PaulUszak

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    I refer to stuff like this. It looks like typical trunking.

    Thing is, I don't know how to use it! I don't consider myself uneducated, but I can't figure out how to put together a run with corner and tee connectors. The only way I can assemble a run is to attach it piece by piece as I go along. So attach back channel. Clip on front. Slide on corner connector and repeat. Since the front covers go under the corner fittings, and the corner fittings have to slide onto the back channel (they do not clip on from the front) you just end up creating a closed conduit.

    And that all means that it cannot be opened up again later somewhere, without disassembling the whole run.

    If the corner and tee fittings clipped on from the front like other ranges, it would all be fine and dandy. Since 38 reviewers gave this weird stuff 4 /5 stars, I must be missing a trick.

    I'm probably having a brain fart, but really need help.
     
    Last edited: 7 Mar 2017
  2. EFLImpudence

    EFLImpudence

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  3. PaulUszak

    PaulUszak

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    Okay thanks but none of that is Tower trunking. I tried to be explicit in the fact that the corner and tee fittings DO NOT CLIP ON FROM THE FRONT. They slide on as far as I can tell. That means that a large run has to be started at one end and fully installed as you go along, and then cannot be opened afterwards. You might as well use conduit then.

    Proper trunking (steel) and cable tray covers screw on from the front. This plastic stuff is a bit useless unless someone with experience can tell me how to use it effectively. Would it be imprudent to say that I reviewed YouTube, ScrewfixTV and Schneider Electric prior to posting?
     
    Last edited: 8 Mar 2017
  4. EFLImpudence

    EFLImpudence

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    I cannot find any pictures of screwfix pieces but normally these bits just clip on after you have installed the trunking and cable and fitted the cover/lid - they can be removed afterwards if you want.

    Can you post a picture of the parts you have?
     
  5. EFLImpudence

    EFLImpudence

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    Like this - round but the same.

     
  6. Iggifer

    Iggifer

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    Can't say as I've had any problems with it on the few occasions I've used it.

    The 25x16 flat elbows certainly look normal from the photo.

    You are cutting the lid 5mm or so short each time aren't you? This allows whichever cover piece you're using to snap over the top of the lid and attach to the trunking whilst being removable.

    If you slide it under a lid the yea it will catch and be difficult to take apart.

    Have you tried snapping a fitting onto a piece of trunking off the wall with no lid? This should show you if it will snap on. They often need a fair amount of persuasion.
     
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  7. PaulUszak

    PaulUszak

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    This is the channel profile in section:-

    upload_2017-3-7_23-9-29.png

    From what's been said here by others, I think I know the reason I'm stuck. If you look closely, you'll see that the open side is slightly tapered together. I have 4m of trunking exactly the same. This means that the tees and corner pieces cannot simply clip on, no matter how hard you wack them. The only way to attach them is to spread the channel with your fingers and slide the connectors on as you go along. You're effectively forced into making a fully enclosed conduit through which you then have to draw the wiring. They then engage extremely well, so well in fact that you can't get them off without damaging them.

    This isn't the first time screwfix have sold me duff stuff. See this post regarding plasterboard fixings. The irony is, this trunking is why I bought the plasterboard fixings.

    What did Charlton Heston say at the end of that film, "God damn screwfix to hell!"
     
  8. EFLImpudence

    EFLImpudence

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    Of course you may have a duff piece but I'm still puzzled by your description.

    Process -
    1. Fit channel to wall - complete run if wanted, including around all corners.
    2. Place cable in first length of channel - temporarily secure at far end so it doesn't fall out.
    3. Affix cover to first length of channel.
    repeat 2 & 3 for subsequent lengths of channel.
    4. Place all corner pieces and T-pieces over completed trunking.
     
  9. PaulUszak

    PaulUszak

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    You're absolutely correct. That's exactly what I thought, and it's what I've always done with trunking. So off to screwfix I went whistling a merry tune :)

    Your step 4 is impossible. :(

    If you look at my piccy, the short sides of the trunking are moulded so that they're not perfectly rectangular. The corner and tee pieces do not clip on. The receiving clips in them do not engage the rebates in the channel. No degree of whacking, wiggling or bodging will get them to go on. And. Since the covers go under the corner and tee pieces, they can't be fitted either. So having completed your steps 1-3, I had to take the whole thing off the wall. I then put it back forming a fully enclosed conduit as I went. I then drew the wiring through.

    I don't have a camera to hand to show the exact mis match, but from what you've said (and all the good reviews) I must conclude that my channel is badly moulded. And I've chopped and drilled it so I can't realistically take it back :mad: Anyway, I've got it up eventually, but god help me if I ever have to include another cable :mad::mad:

    PS. I know it's difficult to be convinced, but I tried yet again with some off cuts just before pressing the Post Reply button. No luck. Visualise yet more angry emoticons here...
     
  10. ban-all-sheds

    ban-all-sheds

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    I don't use the stuff very often, but when I do I make mitred corners.
     
  11. Lectrician

    Lectrician

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    You aren't mixing makes are you?
     
  12. aptsys

    aptsys

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    Works fine for me and all of the trunking has that profile.
     
  13. PaulUszak

    PaulUszak

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    So, first image is how it's meant to be. This is from the underside, as if you were the wall. This was only achieved by sliding the corner piece onto the trunking channel with the top cover already in place. Consequently the wiring has to be drawn through the trunking as if it were conduit.

    upload_2017-3-8_13-18-0.png

    This is what you guys are telling me should work, and what is the obvious way to me too:-

    upload_2017-3-8_13-19-1.png

    Doesn't look like far to go eh? It is physically impossible (in my opinion) to get the corner piece to engage from this position. Gently pressing the corner just deforms the channel. Whacking it with a hammer deforms the whole lot. The clips will not engage. You can see that the corner clip overlaps the channel clip in such a way that it is opposed to engaging. It almost looks deliberately designed to resist mating from this position.

    I think that the channel has been moulded poorly. The above would work perfectly if the sides of the back channel had been moulded more rectangular than what I posted earlier.

    I'm confident that all the parts are from the same range. I guess that I could have cut the little clips off, but I'm not sure if the tees and corners would have subsequently stayed on. I could glue them I suppose.
     
    Last edited: 8 Mar 2017
  14. ban-all-sheds

    ban-all-sheds

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    How long are the runs?

    I've always found that the covers are bendy enough to allow them to be clipped on at each end with the rest lifted away from the channel, i.e. so that the ends of the lid don't reach the ends of the channel, and then pressed into place so that the ends slide along.
     
  15. PaulUszak

    PaulUszak

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    They range approximately 1700 mm to 150 mm. It gets a bit messy in the area of some equipment enclosures. I think that you're right. With hindsight I could have done most of it your way.

    The real learning here is that I should have used the stuff from downstairs upstairs. It was from B&Q. Their plasterboard fixings worked too.
     
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