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Thread: Ty Raps to support rigid PVC??

  1. #1
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    Ty Raps to support rigid PVC??

    I can't find anywhere in the NEC that specifically prohibits using ty raps to fasten PVC to building frame members. I have a contractor fighting me on this issue. We have a newly constructed greenhouse at our new high school; the interior is classified as a wet location. I made them remove tie wire in a couple of areas where they had to run conduit parallel to existing strut. Since unistrut straps will only work on a perpendicular install, they went back with ty raps. I'm trying to get the engineering firms to get them to add strut where neccesary, but in the meantime I'm trying to find out if ty raps are prohibited for use as a means of "fastening". ??

  2. #2
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    I do not think the NEC prohibits using ty-raps. There have been some previous threads on this subject, and that seemes to be the consensus. It was also offered that the AHJ would have to approve the method you submit.
    db

  3. #3
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    Quote Originally Posted by ssandoval View Post
    I can't find anywhere in the NEC that specifically prohibits using ty raps to fasten PVC to building frame members. I have a contractor fighting me on this issue. We have a newly constructed greenhouse at our new high school; the interior is classified as a wet location. I made them remove tie wire in a couple of areas where they had to run conduit parallel to existing strut. Since unistrut straps will only work on a perpendicular install, they went back with ty raps. I'm trying to get the engineering firms to get them to add strut where neccesary, but in the meantime I'm trying to find out if ty raps are prohibited for use as a means of "fastening". ??
    Not sure about PVC but its OK for MC as a means of securing. 352.30 dosen't mention by what means.
    "Appliances and wiring will burn out to protect fuses"

  4. #4
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    Quote Originally Posted by ssandoval View Post
    I can't find anywhere in the NEC that specifically prohibits using ty raps to fasten PVC to building frame members. I have a contractor fighting me on this issue. We have a newly constructed greenhouse at our new high school; the interior is classified as a wet location. I made them remove tie wire in a couple of areas where they had to run conduit parallel to existing strut. Since unistrut straps will only work on a perpendicular install, they went back with ty raps. I'm trying to get the engineering firms to get them to add strut where neccesary, but in the meantime I'm trying to find out if ty raps are prohibited for use as a means of "fastening". ??
    Using a menralac one hole pipe clamp with a uni-strut nut will allow securing to the uni-strut in any direction, and I agree the NEC allows wire ties to secure conduit, but the problem with PVC is expansion, like vinyl siding it must be allowed to move, this means the straps or clamps used must allow the pipe to slide through them, and expansion joints must be used when runs are over a certain length, or you wind up with a spaghetti mess. 352.30

    When a job call for exposed PVC I tend to install more supports than the code requires, to keep it running straight table 352.30 allows 1/2"-1" to be supported every 3' on 1/2" I do 2' supports, I even go over board with expansion joints, when the conduit is between fixed points, or 90° turns, but here we can have over 90° temp in the summer and go down to -10° in the winter.
    Inside runs are not as much a problem in a controlled environment, but it does seem to shrink over time when exposed to high temps, which can pull out of boxes and fittings.
    Wayne A. From: N.W.Indiana
    Be Fair, Be Safe
    Just don't be fairly safe

  5. #5
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    Thanks to all for the replies. I'm going to try to go with the fact that the installation literature for ty raps considers them to be "cable ties", I'll let everyone know how it pans out.
    Still learning something new everyday...

  6. #6
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    Quote Originally Posted by ssandoval View Post
    Thanks to all for the replies. I'm going to try to go with the fact that the installation literature for ty raps considers them to be "cable ties", I'll let everyone know how it pans out.
    They aren't just for cables any more.
    http://cableorganizer.com/articles/c...-use-ties.html
    Just because you can, doesn't mean you should.

  7. #7
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    There are SS cable ties available...
    A regular cable tie has a breaking strength, the suitable of that tie would depend on the weight of the conduit with wires included.
    Moderator-Washington State
    Ancora Imparo

  8. #8
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    What's the reasoning behind all this?

    You just don't like zip ties? Or does their conduit look like crap?

    If everything else is installed correctly, amount of straps and exp. fittings where required, etc who cares what they use for strapping as long as it's sufficient to hold the pvc in place?

    Like anything else, if you have a preference, you should of put it in the specs...

  9. #9
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    Nothing wrong with using tie wraps, tie wire or even duct tape. It isn't a matter of what you want to see but a matter if it does the job or not.

    I have installed many of a feet of 2 inch and larger by simply laying in the bar joist with nothing to hold it in place except the bracing of the bar joist.

    Remember you want it to be able to move not be rigidly locked in place so it can’t move.
    Mike Whitt
    God answers Knee-Mail.

  10. #10
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    Wow. I'd never consider tie wraps as an acceptable support for conduits. IMO, I don't see how this complies with the NEC.

    But I'm apparently in the minority (or even all alone!!).

    Edit: I re-read the original post - the first time I read it I didn't see that the conduit was resting on framing members. I might be able to accept tie-wraps for securing - I thought they were using them to support the conduit.

    Still, I wonder how they will hold up in the sunlight??
    Last edited by steve66; 01-05-12 at 07:04 PM.

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