Old box

I'm replacing and old Rittenhouse doorbell transformer as part of a smart doorbell upgrade. My problem is that the screw spacing of the cover (of which the transformer is embedded) doesn't seem to match any modern-day cover spacing.

The transformer is part of a 4" door cover; there's several joined circuits inside the box so I really don't want to have to replace the box itself. But I can't find a cover that meets these screw holes - they are 7/8" from the opposite sides and 3/8" from the top/bottom (in the pic they are the upper right slot and the bottom left hole). A standard 4" box cover does not line up with these holes at all.


The diagonal hole-to-hole measurement is 4 1/4". Also note, my goal here is a plate with a 1/2" knockout to mount the new transformer. I've got an existing 4" plate (that I could drill out, I presume) if that's the best way.


Any thoughts on what might work here? Is this spacing called something else that I'm not searching for correctly?

  • Make one out of thin sheet plastic. Or buy a blank that fits and drill holes to fit. – Alaska Man Apr 6 '19 at 21:53
  • 1
    Give the dimension directly between the mounting holes on the electrical box. – Michael Karas Apr 7 '19 at 0:33
  • Yes, can you show us the box this was mounted to? – ThreePhaseEel Apr 7 '19 at 2:17
  • @MichaelKaras what do you mean by "between"? From where to where? – Joe Apr 7 '19 at 3:22
  • Center of cover hole to center of the other hole. This would be diagonal across the box between the holes that the transformer cover had mounted to. – Michael Karas Apr 7 '19 at 4:25

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