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Community and Q&A

Does anyone know how to extend a FSE box depth after instal?

Bikercook | Posted in GBA Pro Help on

Hi, during my cement block home build my contractor (long gone) installed these boxes 

Now after finish work and wiring was done, (by third world nice but inept workers),  most need to be extended, some up to 1 3/4″.
Can anyone come up with something that will work? There are no Building codes here…, but I want my switchplates and outlets to be stable and flush to the differing depth plaster walls. The wiring was just completed after a month of tracing wires. (First electrician past away without notes, by a friend of original guy who regretfully was the nice but inept guy)!

I’m at wit’s end with this 10 year build ..

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  1. Expert Member
    DCcontrarian | | #1

    Are you using FSE boxes because you need them to be waterproof? You can get box extenders that just use the device screws. You might need longer screws but you could stack them up to get 1-3/4".

    1. Bikercook | | #3

      Thanks so much. Thought I would get an email if I had a response. Sorry but THANKS

  2. Expert Member
    BILL WICHERS | | #2

    I think what you're saying is that the electrical boxes are mounted behind walls with varing thicknesses of plaster or drywall. You normally use "mud rings" for this sort of thing, which can be found from really shallow ~1/4" up to several inches deep. They normally mount on 4" square boxes though, and they are supposed to be installed BEFORE the finished wall goes up. I suppose you could mount one on a box and then patch around it, but patches on the edges of a hole like that don't usually hold up well and tend to crack.

    If you have "regular" single gang boxes, you need to use "box extenders", such as the example at the link below. These can be installed from the front of the wall, and act like a longer box. You usually need long 6-32 thread screws when dealing with things like this.
    Note that there are several styles of these available.

    I personally really like:
    To get the device (receptacle or switch) flush with the finished wall surface and still have a secure mounting. These go between the box and the device mounting tab, and can be snapped together to allow adjustment in about 1/16" steps. These are great, but you still need a box extender too for deeper walls.

    If your boxes are bell boxes installed on concrete, then you can extend them with these:
    You talk about plaster walls, so I'm not entirely sure what you're dealing with here.


    1. Bikercook | | #4

      Yes Thanks Bill. They are in concrete walls with differing thicknesses of brown coat and finish coat. They were not thinking when they installed them as to the correct depth. These items you mentioned are exactly what I need. Thanks again

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