On Monday, September 28, 2015 at 10:54:53 AM UTC-4, HerHusband wrote:
After removing the fixtures themselves, I was left with the mounting
plates shown in the following picture.

http://i440.photobucket.com/albums/q...927_132127_zps
sjkqsr1x.jpg

When I removed the plates I found that the electrical boxes were not
attached to the studs, instead they were attached directly to the back
of mounting plates using a threaded tube and strap, similar to this
setup:

http://i111.photobucket.com/albums/n...j/DSC03039.jpg

The threaded tube came through a hole in the center of the mounting
plate and was secured with a nut. The mounting plates themselves were
screwed through the wallboard into a stud. Obviously, when I removed
the plates, the electrical boxes came out with them.

The strap and threaded tube is a standard mounting system for most light
fixtures. However, the box itself should have been secured to the wall in
some way, even without the light strap.

If you can't secure the box to a stud, the easiest option would be to pick
up a "remodel" style box. These typically have a flange on the front and
tabs of some type that swing out from the back to secure the box to the
drywall.

Thanks for all that, although it wasn't really a "how to" question. It was
more about whether or not the method used was an acceptable method.


That said, if your light fixtures have any signficant weight, you should
really find a way to secure the box to a stud for support.


That said, the thickness and size of the steel plate and the fact that it was screwed to the stud with big honking screws gave me no concerns about the support of the fixture and electrical box. A couple of screws through the side of the box itself or tabs to support the box against the back of the drywall would merely be adding suspenders to the belt. Trust me, those mounting plates (and therefore the electrical boxes) weren't going anywhere.