I used 18 solid (place doesn't exist where I got it anymore though, sorry) on my first canopy for the fluorescent sockets. Unfortunately I nicked some of the insulation and eventually the stuff starting arc'ing and that was the end of that.
I can't think of any of the wiring places. I'm thinking of a place just off 32nd near Barlow that will have it for sure, but confound it I can't remember the name now.
Man, how useless is this reply?
Sorry I'll maybe PM you tomorrow when I remember the name of the place.