Some light tinkering in the house this afternoon. I needed to figure how much of a drop there is in my drop ceiling because I want to fit a ceiling fan but didn't know how much space I had to work with. Based on an adjacent room I figured I'd have 2x4s forming some kind of pattern but didn't know which way they would run. I was able to make a hole through from the other side so I could shine a light.
It turns out that, much as expected, I've got 2x4s running with wood strips pinned perpendicular, which in turn hold the ceiling tiles. That makes it a nuisance because my back boxes suitable for fans wouldn't have much grip in the bottom of the 2x4s, meaning a significant chance of the whole lot breaking away and meeting the ground at speed. I could conceivably screw a shim into the bottom of the 2x4 but I'm not sure whether I'd end up with screws that screwed in between the two pieces of wood, and therefore still didn't have any meaningful strength. I don't think cutting a piece out of the bottom of the 2x4 so I could screw a bigger shim into place is a viable option because whatever I do needs to happen through a single 4" circular hole. There is a doodad I can buy that is designed for situations similar to this but I need to check to make sure it can bite into joists that are 3/4" higher than the bottom of the ceiling surface. Then I just need to figure out how to get a piece of cable from the nearest power point to where I need it to be.
I think running the cable will be relatively easy but I'm going to need a bigger back box to hold everything. I'm going to end up with three and maybe four three-way switches, plus a power cable in and a power cable out, plus the cables that feed the remote three-way switches. It's going to be a bit of a jumble in there.