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  1. #1
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    Mar 2009
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    Default Firestop For Plastic Electrical Boxes

    Are there any firestop requirements with regard to those blue plastic electrical boxes? I see them used a lot, myself included, and the knockouts that you run wire through leave me unsettled. My guess is that a few sparks could easily jump out of the box and catch on framing. Something i'm missing here?
    My advice and opinions come from hands on knowledge...and This Old House Hidden Content

  2. #2
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    Default Re: Firestop For Plastic Electrical Boxes

    Gizmo

    Cut it 3 times & it's still to short.
    Inventor of the Miter Master Plus.

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  3. #3
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    Default Re: Firestop For Plastic Electrical Boxes

    Quote Originally Posted by dcalabro View Post
    Are there any firestop requirements with regard to those blue plastic electrical boxes? I see them used a lot, myself included, and the knockouts that you run wire through leave me unsettled. My guess is that a few sparks could easily jump out of the box and catch on framing. Something i'm missing here?
    For standard use there's no need for any extra firestop .
    Unless the boxes you are using come from some black market source then they should meet all compliance ratings.

    Besides, have you looked at a metal box --- they're not exactly hermetically sealed either.
    "" an ounce of perception -- a pound of obscure "
    - Rush

  4. #4
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    Default Re: Firestop For Plastic Electrical Boxes

    Quote Originally Posted by canuk View Post
    For standard use there's no need for any extra firestop .
    Unless the boxes you are using come from some black market source then they should meet all compliance ratings.

    Besides, have you looked at a metal box --- they're not exactly hermetically sealed either.
    True but I guess I just assumed knocking a hole in a plastic box is worse than a knockout on a metal box to which you can use a cable clamp to seal that penetration. While neither solution is would be a perfect firestop, I assumed there was something else to be done.

    Thanks for the link to the putty.
    My advice and opinions come from hands on knowledge...and This Old House Hidden Content

  5. #5
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    Default Re: Firestop For Plastic Electrical Boxes

    Quote Originally Posted by dcalabro View Post
    True but I guess I just assumed knocking a hole in a plastic box is worse than a knockout on a metal box to which you can use a cable clamp to seal that penetration. While neither solution is would be a perfect firestop, I assumed there was something else to be done.

    Thanks for the link to the putty.
    One main reason for the box is to keep device connections and splices from direct contact of combustible materials --- unlike open air splices which when buried in a wall are more likely to be in direct contact with combustibles.
    "" an ounce of perception -- a pound of obscure "
    - Rush

  6. #6
    Join Date
    May 2008
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    Default Re: Firestop For Plastic Electrical Boxes

    I've only seen fire caulking required where the box is installed in a fire-rated wall, such as the wall between the garage and house. I think plastic boxes may be permitted when properly caulked.

    Carlon (a maker of plastic electrical boxes and other devices) has an interesting white paper regarding the fire safety of PVC electrical conduit & raceways. They assert that a plastic device may provide greater protection than a metal one.

    http://www.carlonsales.com/techinfo/...ding_Codes.pdf
    The "Senior Member" designation under my name doesn't mean I know a lot, it just means I talk a lot.I've been a DIYer since I was 12 (thanks, Dad!). I have read several books on various home improvement topics. I do not have any current code books I can refer to. I was an apprentice plumber for two years.

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