It's been awhile, but this sounds somewhat familiar... Some Boxes are supposed to be for Fans, but say the Fan has to be supported indepentantly of the Outlet Box (screw through Box). Maybe that's what he means?

I found the following for one Brand:

Quote
Weight Limits: Fans and fixtures are supported independent of outlet box. Mounting screws go through box and into joist.
Box will support up to 70 lbs. for fans and 90 lbs. for fixtures.


This sounds a bit misleading, as the box isn't actually supporting anything if the mounting screws go into the joist.

http://www.cooperindustries.com/con...iling%20Fan%20Boxes%20and%20Supports.pdf

Bill

Bill