Shallow Wall Cavity for Junction Boxes, Cut Back of Boxes or Surface Mount?

Discussion in 'Electrical Forum discussion & Blog' started by molo, Nov 10, 2012.

  1. molo

    molo Member

    Messages:
    845
    Location:
    cold new york
    Hello,
    I need to install a few junction boxes in an old home. I've tried to use the standard old-work boxes, but they are too deep.

    I've considered cutting the back of the box, but not sure if this is acceptable. I'm also wondering if there is a decorative surface mount box available?

    Thanks in Advance!
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,058
    Location:
    New England
    No, the whole idea of the box is that it is enclosed when the cover is on...cutting the back off defeats that purpose. I've seen (and used) some shallow boxes. Keep in mind they limit considerably what you can put in them both in devices and cables.
  3. molo

    molo Member

    Messages:
    845
    Location:
    cold new york
    I was considering modifying a box by drilling two holes in the bottom for romex connectors. This would allow me to bring the wires into the box from a location other than the back of the box. I could then make a new back for the box that could be held on by a couple of small bolts and washers.
    I can't seem to find a shallow box elsewhere so am considering options.
  4. cacher_chick

    cacher_chick Test, Don't Guess!

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  5. molo

    molo Member

    Messages:
    845
    Location:
    cold new york
    The problem is depth of the conventional boxes. When they go into the wall they hit studs, or sheathing. I only want to join two pieces of 12-2 together so don't need much space.

    This does raise the question about the amount of open space in the plastic boxes around where the wires enter the box. The plastic tabs leave quite a bit of open space once the wire is pushed into the box, which makes me wonder what the problem is with not having a back on the box?
  6. ActionDave

    ActionDave Electrician

    Messages:
    346
    Location:
    Colorado
    How deep is the cavity? A shallow 1900 box, also called a four square, is only 1 1/8" deep. You could also surface mount it, or come in the back of a wire mold box.
  7. Speedy Petey

    Speedy Petey Licensed Electrical Contractor

    Messages:
    996
    Location:
    NY State, USA
    There is no "conventional" box. Cut-in boxes come in all differeent depths.



    PLEASE stop wondering this. You are questioning 125 years of code changes. The box needs to be in tact for a reason!



    WHY are you coming into the back of the box? NM cables enter the bottom of every plastic cut-in I have ever used.


    May I ask why you have to splice these cables in a finished wall???
  8. molo

    molo Member

    Messages:
    845
    Location:
    cold new york
    Thanks Dave,
    I'll look for those boxes.
  9. Homeownerinburb

    Homeownerinburb New Member

    Messages:
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    Location:
    Los Angeles, CA USA
    You do not need boxes to splice NM.

    There are recently approved spice devices that cost about $6. They have a pretty solid grip on the cable such that the join is not going to be pulled apart, which is the key reason that just wire nutting in a wall cavity is illegal.

    And just how deep is the wall void that you are working with?
  10. big2bird

    big2bird IBEW Electrician

    Messages:
    141
    Location:
    Anaheim, Ca.
    Do you have a link for this item?
  11. jwelectric

    jwelectric Electrical Contractor/Instructor

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    North Carolina
  12. hj

    hj Moderator & Master Plumber Staff Member

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    Location:
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    quote; remember that it has to be accessible

    ANd the easiest way to make it "accessible" is to make the connection in a box. So he is back to his original question, and the answer is a shallow box, but since an "old work box" with toggles does not come in a shallow pattern, he needs the sheet metal "T" grips that fit into the opening on either side of the box, then bend around the side edges to hold it in place.
  13. molo

    molo Member

    Messages:
    845
    Location:
    cold new york
    The local hardware has a plastic box that is only 1" deep. It has a knockout on the top and bottom. It doesn't have the screw-tightened tabs that the "old-work" boxes do.
  14. Jim Port

    Jim Port Electrical Contractor

    Messages:
    156
    Location:
    Maryland
    You may not think you need that much room but the required space is specified by the electrical code. For 2 12-2 cables without a device you need at least 5*2.25 cubic inches. with a device you need at least 7*2.25.
  15. cacher_chick

    cacher_chick Test, Don't Guess!

    Messages:
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    Location:
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    I'd be curious to see what you are working on, as all the old houses around here used "real" 2"x4" studs with lath and plaster walls. There is just as much space inside those walls as are found in most new construction today. Maybe it's just a matter of putting the box somewhere other than the exact location that you have looked at.
  16. Homeownerinburb

    Homeownerinburb New Member

    Messages:
    525
    Location:
    Los Angeles, CA USA
  17. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,534
    Location:
    North Carolina
    Only in mobile homes and RVs can they be conceled.

  18. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
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    Location:
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    quote; as all the old houses around here used "real" 2"x4" studs with lath and plaster walls.

    I worked in a Frank Lloyd Wright house which had 2" and 3" walls, He did not believe in wasting space for walls when it could be used for live in purposes.
  19. bsperr

    bsperr Member

    Messages:
    74
    Location:
    Athens, GA
    What's inside the wall that is preventing the box from sitting flush and how proud does it sit from the wall? A picture of two would be very helpful. If the box is being obstructed by something inessential, like blocking or nailers on an interior wall, I would take a spade bit and drill out some of that material through the cutout for the box until it sits flush. Obviously, you wouldn't be able to do the same thing if the box was butting up against the exterior sheathing.
  20. molo

    molo Member

    Messages:
    845
    Location:
    cold new york
    Thanks for your response, I was able to find some shallow plastic boxes (1" deep) They have tabs that go over the face of the wall surface, and say that the cable must be attached within 12" of the box.

    Also,It's interesting that those splices can be made in RV's and trailers and not homes. Why is this?
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