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  1. #1
    Join Date
    Mar 2007
    Location
    New Mexico
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    1,258

    Default Box Fill Question

    This if for my own remodel project. I think I have it correct, but wanted to double check. I have a 2 gang deep box, blue plastic from Carlon. The box states that it is 34.6 cubic inch. Because of some logistics problems, I need to put six 12-2 wires (with ground, of course) into the box, plus one single pole switch and a receptacle. According to my calculations, I have 12x2.25 for the 12-2 wire, 2.25 for the ground, and 4.50 for the two devices. That totals up to 33.75.

    Am I in compliance with the 2008 code? I can go to a 64 cubic inch box if I need to, by using a 4 square and adding an extender onto it, if needed.

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    Jim Robinson
    New Mexico, USA

  2. #2
    Join Date
    Apr 2009
    Location
    NY State
    Posts
    440

    Default Re: Box Fill Question

    The only mistake is that each device counts two conductors. So unfortunately that pushes you just over the limit for that box.


  3. #3
    Join Date
    Mar 2007
    Location
    New Mexico
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    Default Re: Box Fill Question

    Right. I knew it seemed too easy. Back to the 4 square metal and extension ring tomorrow. For the connector clamps, it's just one for the whole box, right? Or is it 2.25 for each clamp?

    What is a fixture fitting, by the way?

    Jim Robinson
    New Mexico, USA

  4. #4
    Join Date
    Aug 2008
    Location
    Maryland
    Posts
    1,898

    Default Re: Box Fill Question

    If the clamping is outside the box you do not need to account for any volume for it.

    A fixture fitting would be like the old female threaded studs that were typical on very old fixtures. A threaded rod screwed into them to support a globe sometimes.


  5. #5
    Join Date
    Mar 2007
    Location
    Ormond Beach, Florida
    Posts
    26,248

    Default Re: Box Fill Question

    Quote Originally Posted by Jim Port View Post
    A fixture fitting would be like the old female threaded studs that were typical on very old fixtures. A threaded rod screwed into them to support a globe sometimes.
    Those female thread fittings were called "hickeys" and were available as cast pieces with female threads in both ends and an open area in the center. Those are still available, however, the newer ones are simply a sideway 'U' with the two legs having female threaded holes in them.

    I'll try to find some photos of them.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  6. #6
    Join Date
    Mar 2007
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    Ormond Beach, Florida
    Posts
    26,248

    Default Re: Box Fill Question

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  7. #7
    Join Date
    Mar 2009
    Location
    Colorado Front Range
    Posts
    601

    Default Re: Box Fill Question

    If it was me I'd be for using a deep (2 1/4 inch) 4 11/16 box with a mud ring. This eliminates the need for an extender.


  8. #8
    Join Date
    Mar 2007
    Location
    New Mexico
    Posts
    1,258

    Default Re: Box Fill Question

    That would work. I'm not sure if I can find the mud ring here. I'm pretty sure they have that size box at the hardware store. There may need to be a trip to Lowes in the near future, but that would be a lot easier than my convoluted stacking of boxes.

    Jim Robinson
    New Mexico, USA

  9. #9
    Join Date
    Apr 2009
    Location
    Manchester, Vermont
    Posts
    298

    Default Re: Box Fill Question

    Jim Robinson

    I counted a total of 38.25 C.I.

    six 12/2 total of 27.00 C.I

    Two devices total of 9.00 C.I.

    Ground wire total of 2.25 C.I.

    Your final total is: 38.25 C.I.

    In one of my mail order catalog, they list a plastic, two gang nail on
    Cat. NO. SN-241 its CU. IN. is rated at 41.0 C.I. price at $1.30 Ea.

    Most 4"Sq, x 2-1/8" deep, with1/2" & 3/4" K.O.'s are rated at
    30.3 C.I. NOT MUCH HELP HERE. Although mud rings have a C.I. rating
    you need the MFG. book to find out what it is.

    Your next chose is a 4-11/16 x 2-1/8 deep, they run 42.0 C.I.
    Then you would need to purchase a cover for 4-11/16 square box.
    Which can be had. But I have never seen one at the HOME DEPOT in
    my area.

    So short of mail order.

    Go to a electrical supply house, there you should be able to do one stop
    shopping. In my area, I always call ahead, just to make sure they what
    I am looking for.

    Good Luck


  10. #10
    Join Date
    Mar 2007
    Location
    New Mexico
    Posts
    1,258

    Default Re: Box Fill Question

    I can mail order the mud ring, that's no problem. Or I can get down to Santa Fe and pick one up at the electrical supply house. We have the large boxes here. Either way, doesn't sound like I'm in any trouble getting into compliance. I thought that box was awfully tight when I was cramming the wires in there.

    Jim Robinson
    New Mexico, USA

  11. #11
    Join Date
    Apr 2009
    Location
    Manchester, Vermont
    Posts
    298

    Default Re: Box Fill Question

    Personal I would go to an electrical supply house, if not more than 30 miles away.

    I figure it will cost me $5.00 in gas, depending on what vehicle I drive.

    Mail order usuall start of with a $5.00 flat rate than .98 cents for each
    pound.


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