I'm looking for the best method to install receptacles in the middle of a drop ceiling tile. Caddy & B-Line have brackets to support 4" boxes, but if I install a tile-ring and receptacle, I think the force from inserting the plug will push the whole thing (t-grid and all) upward, resulting in a sloppy installation.
I cut a piece of 3/8 plywood to the size of the ceiling tile. I put it right on top of the ceiling tile and use a 1" plaster ring on a 4" box supported by a Caddy 512. The plywood lends weight and stiffness to the whole thing. Keep in mind that ceiling plugs usually get 1 item plugged in and it stays there. They are rarely used as true convenience receps.