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Thread: 1” RNC (PVC) support to unistrut

  1. #1
    Join Date
    Jul 2018
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    Phoenix, AZ, USA
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    1” RNC (PVC) support to unistrut

    Hello does the NEC say anything about securing RNC (PVC) to unistrut? I inspect industrial electrical projects. I have always used rigid strut straps, but is there an issue with using a 1” EMT strap? Is there some UL listing issue/NEC issue?

    Thanks!

  2. #2
    Join Date
    Feb 2003
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    Bremerton, Washington
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    Have you reviewed Art 352?
    And the strap would be listed or labeled by the mfg for the conduit type allowed.
    Moderator-Washington State
    Ancora Imparo

  3. #3
    Join Date
    Dec 2006
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    Eastern Oregon
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    Depending on the length of the run, a regular strut strap may or may not work for the expansion/contraction that will take place.

    We use a lot of regular strut straps on stubups into the bottom of enclosures, but use other means where the conduit has any distance to it.

  4. #4
    Join Date
    Dec 2015
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    Yakima, WA
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    as Tom mentioned, NEC requires it to be listed for use with PVC, which regular strut straps are not. They do make some plastic ones but they are easily broken. Are you the AHJ in your area?

  5. #5
    Join Date
    Jun 2004
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    Cherry Valley NY, Seattle, WA
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    Ok, I'll say it: I have used strut straps on pvc for 20 years and never had a problem, nor heard of anyone having a problem. Sometimes I even mix a TW with a HW wall so the bolt is angled - makes it easy to tighten up when there are multiple pipes in close proximity.
    Ethan Brush - East West Electric. NY, WA. MA

    "You can't generalize"

  6. #6
    Join Date
    Dec 2015
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    Yakima, WA
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    Quote Originally Posted by electrofelon View Post
    Ok, I'll say it: I have used strut straps on pvc for 20 years and never had a problem, nor heard of anyone having a problem. Sometimes I even mix a TW with a HW wall so the bolt is angled - makes it easy to tighten up when there are multiple pipes in close proximity.
    POCO does it all the time here. Yes, they get to make their own rules but still done everyday. I have also done it where it was impracticable to use the plastic crap (so pretty much always ) but it was approved by the inspector as well

  7. #7
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    Mar 2003
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    vinyl coated strut clamps are available, but very $$$

    ~RJ~

  8. #8
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    Feb 2003
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    Illinois
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    Quote Originally Posted by romex jockey View Post

    vinyl coated strut clamps are available, but very $$$

    ~RJ~
    Those do not meet the requirement in 352.30 that says "shall be fastened so that movement from thermal expansion or contraction
    is permitted."
    Don, Illinois
    (All code citations are 2017 unless otherwise noted)

  9. #9
    Join Date
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    Illinois
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    Quote Originally Posted by MattS87 View Post
    as Tom mentioned, NEC requires it to be listed for use with PVC, which regular strut straps are not. They do make some plastic ones but they are easily broken. Are you the AHJ in your area?
    There is no requirement in the NEC that straps be listed. The only listing requirement for supporting is where tie wraps are used to support flexible wiring methods. There is a specific requirement that the strap for PVC be designed to permit the conduit to move, but it does not require that strap be listed.
    Don, Illinois
    (All code citations are 2017 unless otherwise noted)

  10. #10
    Join Date
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    Location
    Illinois
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    23,816
    The B-line B2417 series of straps are designed to permit the required longitudinal movement of the pipe. I have never used them for PVC, but we use them were there are expansion joints in rigid to permit the required movement. It doesn't make any sense to put the expansion fitting in and then install the conduit is a way that restricts the movement. The inside part of the strap is slightly larger than the OD of the conduit and permits the conduit to slide.
    Don, Illinois
    (All code citations are 2017 unless otherwise noted)

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