There should also be some Teflon-insulated individual shielded twisted pair cable out there rated for plenum use. It has been in use in the commercial sound industry for about three decades now.
Besides temperature rating, the idea is for the insulation not to out-gas noxious fumes in a fire, since inside the plenum said fumes tend to circulate quickly. Conduit serves the purpose of containment for most power wiring, but the added expense of conduit was deemed too costly for "Class 2" wiring. Some of the early versions of plenum-rated cable actually used a metal sheath on the outside, wrapped in a spiral. Then, Teflon got into the act.
The idea of keeping exposed insulation out of plenums came about after a fire in a suburb of my town. It was in a department store, thankfully before opening time on a Sunday. The subsequent investigation showed that gas being emitted from burning insulation in the plenum not only spread the fire very rapidly, but it dropped several workers where they stood. IOW, it wasn't the fire that killed them directly, they were dead before they could make it to the exits due to the poisonous atmosphere. I imagine a lot of the insulation was PVC in those days, or something like it.
Anyway, I've personally run several thousand feet of Teflon-insulated shielded twisted pair; it is architectural microphone cable for plenums, among other things. Back in the day, the trick to removing the outer jacket was just to nick it with the strippers, then it would snap off at the nick line. I would think the usual suspects like Belden, Carol, or West Penn would have it.
