My electrician on a remodel installed all 3.5" circular boxes throughout. I am finding that everything I want to install wants to have a 4" box. I have seen the spider plates, universal crossbars, nothing meets this particular issue:

The box holes are spaced 2.75" apart on the horizontal. All of the fixtures I am trying to use have a plate that mounts to the box, then has holes for studs - spaced 2.75" apart, that you must level on the horizontal and attach the fixture to. If the box holes were diagonal or vertical there would be no issue. The stud holes line up EXACTLY with the box mounting holes - meaning the only way to screw the plate to the box is to use the stud holes which then means you cannot mount the fixture.

enter image description here

What the heck? Any ideas how to solve?

This is the mounting plate that came with the fixture. The circled holes are where the mounting studs for the fixture must go and need to be level for the fixture to hang properly.

Image link copied from comment on an answer

  • So the mounting screws for the light can't go directly into the 2.75" box holes without the bracket? Maybe a picture would help?
    – JPhi1618
    Mar 13, 2019 at 15:13
  • Great idea and I tried - but the holes side to side are not precisely level meaning the fixture would be crooked :( If they were diagonal or vertical the plates that can rotate would get the stud holes precise. Pic: imgur.com/cFUId4f
    – eci
    Mar 13, 2019 at 15:21
  • See this thread, is there a reason the adaptor in the second picture won't work? diy.stackexchange.com/questions/159329/… Mar 13, 2019 at 16:49
  • @eci, please add a picture that illustrates the problem that you are having ..... your description about horizontal and vertical holes is unclear ...... also, does studs mean threaded studs?
    – jsotola
    Mar 13, 2019 at 17:20
  • I will take a pic of the plate mounted, blocking use of the threaded studs. This is the fixture in question: minkagroup.net/images/instruction-manuals/… The two red circled holes are where the threaded studs go through. You must get these horizontally level. You then place the fixture's holes over them, and use a knurled knob and secure. The reason you can't do this is - the actual wall box has its threaded holes horizontally under where these studs holes must be to mount the fixture. Not precisely though, which is why I cannot directly mount.
    – eci
    Mar 13, 2019 at 20:27

2 Answers 2


I believe that an "offset mounting plate" might work for you (click for larger):

enter image description here

Sample swivel offset crossbar

In this type of plate, the front and rear elements are offset from one another so you can have the box mounting screws and the studs for the fixture practically on top of each other.

The box does look slightly recessed into the wall which could work in your favor here. The only issue would be the sconce sticking out too far from the wall, but you may be able to flatten the bracket some to account for that.

There are other styles of this bracket that could work better - I just grabbed the first example I saw.


In my experience most lamps want a 4" "octagon box". The 4" octagon box is a little funny, because it's actually a 3.5" square with the corners clipped. Across the clipped corners it is 4".

The true 3.5" box has a square dimension more like 3", and 3.5" across its clipped corners.

On that plate you showed, the holes you circled are threaded, and the lamp screws into those. The screws mounting the plate to the ceiling box definitely do not go in those holes. Those screws go through two of the slotted holes, as appropriate. Either the radially-slotted ones, or the axially-slotted ones, as called for.

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