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Thread: First Rough In - Basic Question

  1. #1

    Default First Rough In - Basic Question

    So I'm roughing in my first electrical project - my bath refurb.

    Probably a very simple question I hope. I put in a 2 gang box tonight that will hold a switch and a receptacle. In order to get the box away from the door trim a bit, I stacked 2 2x4 pieces (about 10" long) nailed to the door frame stud. Then I nailed the box to that assembly.

    I must say - the box feels like it has a lot of give to it. Is this normal? It's just a normal electrical box - not the really thin walled ones, but the blue, thick walled type with nails on one side. Purchased at one of the big box stores.

    Just for grins I installed the receptacle in it's space (furthest from the nailers) and pushed in/pulled out a couple different plugs just to test. Again, a LOT of movement.

    How do I make the box more sturdy? Or do I? I thought this would be the very easy part.

  2. #2

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    I've never had a box that moved too much after I trimmed it out. If your drywall is cut correctly, the straps of the devices will push against the wall surface when you are done, helping prevent movement. The cover helps as well.

    Make sure the side of the box is firmly against the stud, and the nails are driven tight.

    If you're concerned about it, place a small piece of scrap lumber between the two studs.
    Just my 2¢ worth.

  3. #3
    Moderator & Master Plumber hj's Avatar
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    Default box

    where is the movement occurring? The nails should secure the box very rigidly to the stud, but if those two pieces of wood are moving then you have to secure them better.

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    Plumber jimbo's Avatar
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    You might try to use a horizontal 2X4 to strap those 2 spacers.

  5. #5

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    Yeah - I think the movement is primarily in the 2 short 2x4 spacers. Not sure exactly what is meant by strapping them, but some sort of horizontal brace seems in order.

    I'm learning all the framing concepts, terms, etc. as I go too. The whole thing is a great education, really.

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    One who lurks Basement_Lurker's Avatar
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    If it were me, I would have just put another stud in there at the spacing you want, they're cheap enough that cost isn't a factor. But if you want to stick with what you have got, you could always just secure your two spacer pieces so that they are secure against the stud, install the box, and then put a piece of backing in between the spacers and the stud to secure the box to.

  7. #7
    Aspiring Old Fart, EE, computer & networking geek Mikey's Avatar
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    I never secure my enclosures ("boxes") to a stud, choosing instead to frame in a piece of scrap between two studs, and screw the box (through the back) into that member. This allows:

    1) huge gangs if required,
    2) arbitrary spacing of boxes, which allows pleasing symmetry,
    3) absolutely solid mounting of boxes,
    4) easy removal or additional ganging of boxes after the wall is finished.

    I don't do this for a living, so my time is worth squat, so the extra time to install the brace doesn't count. There are some Code restrictions on how you do this also (see 314.23), but most of them are reasonable. BTW, 314.23 requires that the enclosure be "rigidly and securely" fastened in place.

  8. #8

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    This sounds like a good idea, and it's something I pondered on this box. But the box depth leaves very little behind it to allow much of a cross piece to screw it to. What thickness of scrap do you use for that cross framing member?

    I was able to redo this first box and tighten it up some. Upon inspection of the box construction, I see that its design seems to inherently make them not as secure as they could be. The box tapers toward the back. But if the exterior width remained constant, then the side of the box would stay in contact with the stud or spacer and keep the whole thing from moving.

    I wonder why they make them this way?

  9. #9

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    Quote Originally Posted by Mikey View Post
    1) huge gangs if required,
    Just keep in mind that once you get over 4-gang's worth of devices, the price of covers increases exponentially. And you can't just go out and buy a 6-gang duplex-GFCI-decora duplex-toggle-toggle-toggle cover.
    Choice of colors drops dramatically, also, so remember that if your better half wants a fancy cover with seashells or lighthouses.
    Just my 2¢ worth.

  10. #10
    DIY Senior Member Livin4Real's Avatar
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    Quote Originally Posted by Mikey View Post
    I never secure my enclosures ("boxes") to a stud, choosing instead to frame in a piece of scrap between two studs, and screw the box (through the back) into that member. This allows:

    1) huge gangs if required,
    2) arbitrary spacing of boxes, which allows pleasing symmetry,
    3) absolutely solid mounting of boxes,
    4) easy removal or additional ganging of boxes after the wall is finished.

    I don't do this for a living, so my time is worth squat, so the extra time to install the brace doesn't count. There are some Code restrictions on how you do this also (see 314.23), but most of them are reasonable. BTW, 314.23 requires that the enclosure be "rigidly and securely" fastened in place.

    I thought it was against code to use screws inside a plastic box?
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  11. #11
    Electrical Contractor/Instructor jwelectric's Avatar
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    Quote Originally Posted by Livin4Real View Post
    I thought it was against code to use screws inside a plastic box?

    314.43 Nonmetallic Boxes.
    Provisions for supports or other mounting means for nonmetallic boxes shall be outside of the box, or the box shall be constructed so as to prevent contact between the conductors in the box and the supporting screws.

  12. #12
    Aspiring Old Fart, EE, computer & networking geek Mikey's Avatar
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    First off, I don't use plastic boxes, so screws are OK. As for the support, the Code says the braces must have a "cross section not less than nominal 25 mm x 50 mm...". The guy that wrote that clearly had a problem with the term "cross section", but it could be interpreted either as "a 1" x 2" (at least) is OK" or "you must have a cross section of 2 sq in. or more." In either case, a piece of 2 x 4 is OK, which allows a 2 1/2" deep (metallic) box. You're still OK if you trim the 2 x 4 down to a true 1 x 2 (allowing a 3" box), and maybe OK if you use a piece of 1/2" plywood 4" wide (allowing a 3 1/2" box). (All assuming a nominal 2 x 4 stud with 1/2" drywall.) Maybe Mike Holt's crowd have counted these angels already.

    Cover-plates are indeed a problem. The big box stores carry a snap-together system which will allow you to build one of arbitrary configuration and length, but the result is truly ugly. I've see commercial installations up to 10 or 12 gangs, but have no idea what the cost might be, or where you'd find one. Committing to Decora devices makes the cover-plate issue much easier to solve. Interesting that the Code doesn't seem to care much how the "cover" is constructed (314.25), so this might be the excuse you've been looking for to buy that milling machine.

    If you want a seashell-covered wallplate, my artist sister-in-law makes seashell-covered anythings .
    Last edited by Mikey; 10-30-2007 at 04:26 AM.

  13. #13
    Electrical Contractor/Instructor jwelectric's Avatar
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    Quote Originally Posted by Mikey View Post
    First off, I don't use plastic boxes, so screws are OK.
    let’s not get confused. Screws can be used with ANY box as long as the box shall be constructed so as to prevent contact between the conductors in the box and the supporting screws.


    Quote Originally Posted by Mikey View Post
    As for the support, the Code says the braces must have a "cross section not less than nominal 25 mm x 50 mm...". The guy that wrote that clearly had a problem with the term "cross section", but it could be interpreted either as "a 1" x 2" (at least) is OK" or "you must have a cross section of 2 sq in. or more." In either case, a piece of 2 x 4 is OK, which allows a 2 1/2" deep (metallic) box. You're still OK if you trim the 2 x 4 down to a true 1 x 2 (allowing a 3" box), and maybe OK if you use a piece of 1/2" plywood 4" wide (allowing a 3 1/2" box). (All assuming a nominal 2 x 4 stud with 1/2" drywall.) Maybe Mike Holt's crowd have counted these angels already.
    The ½ inch plywood would not pass. The wording of the code section is clear
    314.23(B) (2) Braces. Metal braces shall be protected against corrosion and formed from metal that is not less than 0.51 mm (0.020 in.) thick uncoated. Wood braces shall have a cross section not less than nominal 25 mm × 50 mm (1 in. × 2 in.). Wood braces in wet locations shall be treated for the conditions. Polymeric braces shall be identified as being suitable for the use.
    The brace must be no less than one inch thick.

    Quote Originally Posted by Mikey View Post
    Cover-plates are indeed a problem. The big box stores carry a snap-together system which will allow you to build one of arbitrary configuration and length, but the result is truly ugly. I've see commercial installations up to 10 or 12 gangs, but have no idea what the cost might be, or where you'd find one. Committing to Decora devices makes the cover-plate issue much easier to solve. Interesting that the Code doesn't seem to care much how the "cover" is constructed (314.25), so this might be the excuse you've been looking for to buy that milling machine.
    Care must be taken when installing the switch cover plate
    404.9 Provisions for General-Use Snap Switches.
    (A) Faceplates. Faceplates provided for snap switches mounted in boxes and other enclosures shall be installed so as to completely cover the opening and, where the switch is flush mounted, seat against the finished surface.

    Quote Originally Posted by Mikey View Post
    If you want a seashell-covered wallplate, my artist sister-in-law makes seashell-covered anythings .
    Her name wouldn’t happen to be Susie would it? (you know the little rhyme about picking up sea shells by the sea shore)

  14. #14
    Aspiring Old Fart, EE, computer & networking geek Mikey's Avatar
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    Hmmm. I've never heard the seashell-seller explicitly named -- it's always just been "She sells...". Another example of my difficult childhood. No, her name is Sharon.

    As for the one inch thickness, the Code doesn't explicitly say that -- it only requires a 1 x 2 cross section, which in itself is a conflict in terms. A cross section is an areal, not linear measure. If they meant at least one inch thick, they should have said so (e.g., "shall have a minimum thickness of 25mm (1 in.) and a minimum cross section of 12.5 sq cm (2 sq in.)"). Having said that, though, I would understand any inspector that rejected a piece of nominal 1x stock, while at the same time would argue that a 4" width of 1/2" or 3/4" plywood would provide a more "rigid and secure" mounting than, say, 1x2 balsa. If pressed for space and subject to rigorous inspection, I'd use an appropriate metal channel and anchor nuts.

    The issue with nonmetallic boxes and screws is interesting. 314.43 says the box "shall be constructed" to prevent conductor-screw contact. The intent is clear, but the language seems to prohibit post-construction measures to accomplish the same thing (e.g., covering the screw heads with insulating material, or using nonconducting screws).

  15. #15
    Electrical Contractor/Instructor jwelectric's Avatar
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    Mikey,
    We need to be careful not to read too much into a code section.

    314.23(B)(2) gives us the minimum size of the support, not less than nominal 25 mm × 50 mm (1 in. × 2 in.), meaning that anything less than 1 inch thick would not work.

    As to the screws in a nonmetallic box see all we need do is look at 314.23(B)(1) where we are told that the screws and nails can pass through the interior of the box. If screws are used to pass through the interior of the box then;
    (1) Nails and Screws. Nails and screws, where used as a fastening means, shall be attached by using brackets on the outside of the enclosure, or they shall pass through the interior within 6 mm (¼ in.) of the back or ends of the enclosure. Screws shall not be permitted to pass through the box unless exposed threads in the box are protected using approved means to avoid abrasion of conductor insulation.

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