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Thread: Roof penetration & support

  1. #1
    Join Date
    Nov 2013
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    Maine
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    Roof penetration & support

    Hi all,
    I happened to run into both of these yesterday. The situation is roof penetrations with small conduit to a device box and JB. Neither have any support besides the conduit. I thought NEC requires support for both of these installations. I think there are only limited exceptions when using multiple pieces of rigid to a JB (no devices). See attached images #1 & 2. The next part is how the contractor should support these. Thanks for any thoughts!
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  2. #2
    Join Date
    Jan 2014
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    chicago, il, USA
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    Are you sure it isn't supported just below the deck line? If not perhaps a piece of Unistrut cantilevered off of the portal for the exhaust fan. I can't see enough of the second one to see a good point for mounting but the same idea would apply.
    The world is round, you will get there no matter what path you take.

  3. #3
    Join Date
    Jun 2017
    Location
    WI, USA
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    Both require support. Second one has unistrut at the base. Use that to add a second tier for back box support.

  4. #4
    Join Date
    May 2011
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    3,776
    314.23 (E).

    Is EMT a 'conduit'? If so then the second one supported by two conduits is okay, provided the conduits have support right under the roof surface less than 18" from the box.

    I'm more concerned about the flexible raceways not having any proper kind of support.

  5. #5
    Join Date
    Dec 2012
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    Placerville, CA, USA
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    EMT is generally distinguished from conduit, which implies rigid or intermediate, threaded.

    Sent from my XT1585 using Tapatalk

  6. #6
    Join Date
    Nov 2013
    Location
    Maine
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    Thanks for the responses. Unistrut under the roof is a good idea, but sure hard to verify after the install
    Yes, lacking support on the LFMC is another item. As is the way they penetrated the exhaust fan. It's above the air flow so will get covered in greasy exhaust. It was supposed to go through the shroud 'breather tube' or through the curb.

  7. #7
    Join Date
    Apr 2007
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    Quote Originally Posted by jaggedben View Post
    314.23 (E). Is EMT a 'conduit'?
    Certainly in the context of (2011) 314.23 (E), since EMT is explicitly listed in the exception as one of the raceways for which a single entry may support a conduit body of a not larger trade size.

    Cheers, Wayne

  8. #8
    Join Date
    Dec 2007
    Location
    NE Nebraska
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    Take a look at sections 314.23 (E) and (F)

    The first picture only has the box supported by one raceway - and it looks like it may even be EMT or RMC with compression fitting - needs to be threaded RMC or IMC and needs to be two raceways providing support.

    Second picture may be fine - if they used a box with hubs designed for supporting the box - I think it needs to be a type "FS" box and the typical "bell box" like pictured in both images is not listed to be supported by incoming raceways.

  9. #9
    Join Date
    Jan 2007
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    2,903
    Quote Originally Posted by kwired View Post
    Take a look at sections 314.23 (E) and (F)

    The first picture only has the box supported by one raceway - and it looks like it may even be EMT or RMC with compression fitting - needs to be threaded RMC or IMC and needs to be two raceways providing support.

    Second picture may be fine - if they used a box with hubs designed for supporting the box - I think it needs to be a type "FS" box and the typical "bell box" like pictured in both images is not listed to be supported by incoming raceways.
    Ever tried threading a box on to 2 rigid metallic conduits ?
    It's always comical to see the illustrations showing that.

    JAP>

  10. #10
    Join Date
    Dec 2012
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    Quote Originally Posted by jap View Post
    Ever tried threading a box on to 2 rigid metallic conduits ?
    It's always comical to see the illustrations showing that.

    JAP>
    Meyers hub?

    Or think like a plumber and have one conduit coming in (rotate the box to attach) and one going out, which you can build starting at the box and dead ending somewhere else.

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