Trying to see if I could mount a fan (something I've done before), I came
upon something I've never seen before. It's an old round box on the
plaster ceiling, maybe 6" or 5-1/2" in diameter. It's shallow (almost a
plate rather than a box) but made of heavy-gauge metal. There is one
maybe 1/4" female thread in the center, and that is the only way to
attach anything to it; the existing light fixture was attached to a
threaded 1/4" post / nipple that was screwed into the center of the box.
There are three round holes on the top (horizontal) face, and rigid
conduit comes vertically into those holes. There is clearly a stud next
to this box, but I cannot tell if the box is attached to it. It seems
very solid and stable compared to modern drywall boxes, though.
So can I hang a fan on it if I can figure out how to mount the fan using
the center thread? I can't remove it without major damage to the
surrounding plaster an moifications to the rigid conduit.
Many thanks for any suggestions!