Let me clarify my requirements a bit. I want a fully dimmable (ideally 1% - 100%) architectural (tubes hidden in valences) fluorescent lighting system which can be controlled by my automation system (Elk) using standard switches.
Well, I'm not an Elk user, and I couldn't afford those spiffy 1% ballasts, but I did get some Sylvania Quicktronic Powersense ballasts (QTP3x32T8/UNV DIM-TCL) to work with my Insteon (Switchlinc V2) switches. these are 100%..5%, and, as I'm sure you have seen elsewhere, the light-power curve for florescent means that 5% power means more like 25% light, but I can cope; particularly because I think the wallet performance factor was huge. (something like $50 vs $200; *10 fixtures. that would hurt me, at least.)
Otherwise, the standard is 4-wire, which as Marc described is two 120VAC lines for power, and two 0-10VDC lines for control. I am not aware of any standard commercial switches which provide this output though X10, ALC, iLine, Lutron?
My original plan was to do some complicated fiddling with a dimmer, controlling a 10V transformer, also paired to an in-linelinc to switch the power. I was QUITE relieved that the switch seems to control the ballast directly with minimum fuss. Of course, the bottom dim levels on the switch do not result in light from the fixture, and it's probably murder on the ballast when that happens.
Also, I don't have any long term metrics on whether or not this will result in premature bulb or ballast failure. I did a lot of research before trying, and had found one message from an Insteon tech suggesting that the triac they used was configured to cut the voltage phase in the same way that "The Real" dimmable controls did.
I'm surprised more people aren't grappling with this issue.
Yeah, it surprised me too... Not because of code, but just because florescent provides MUCH more light, and there are more options for light rendering, spectrum, etc. Florescent WAS horrible in the past... poor CRI, bad ballasts that flickered 60Hz, ... but these days, even the good stuff is cheap.
My only relationship with Insteon or Sylvania is "Customer". Specific items mentioned only for reproducibility.