I'm trying to install a ceiling light in two rooms that didn't previously have hard-wired lighting. After cutting a 4" hole for a circular ceiling box (using a hole saw attached to my drill) I'm finding that the ceiling box I've got might not fit:
The problem is that the ceiling is too thick. There is the original plaster & lath ceiling, and below that another layer of strapping and a fiberboard ceiling. All together, the thickness is 3 or 4". If I set the ceiling box in the hole from the attic, it sits very far from the ceiling surface you'd see from the room below. Because of the distance, I don't think it would be possible to mount a light fixture there.
So, how do I mount a ceiling box in this deep/thick ceiling? Is there a special box (or extension?) for situations like this? Do I need to somehow remove some of the upper layer of old ceiling in order to reduce the depth? Any special concerns for supporting the box?