I have personally seen incandescent and CFL bulbs above diffuser panels in suspended ceiling setups (even more bizarre than a fluorescent shoplight mounted above diffusers mimicking a fluorescent troffer), mercury vapor recessed can lights inside a home, and a restaurant using real antique 100 year old radial wave streetlights (now repurposed as overhead table lighting).

Let's hear your intakes!

In a cold region, a fluorescent fixture with a heater wire wrapped around the tube, to warm it up doing the startup. But it was done in a crude manner, where it was all manual, even the tube was started with a switch instead of a normal starter.


I also saw an HPS lamp used indoors without any protection. The 250w bare bulb was hanging at head height without any cover.

For me, it was when I was exploring the World Theater in Cedar Rapids, IA years ago. The stage had an arch with dozens of carbon filament bulbs in it, all of which I'm guessing dated back to 1915 when it opened. From what I read, it was only used for live performances for a year before switching to movies, and the bulbs were basically abandoned in place. When I visited, it had been turned into a nightclub and the stage area was closed off. I'm not sure if the nightclub (or even the theater) are still there, but at the time everything back there was preserved exactly as it was nearly a century ago.

At a place I stayed in in Florida, it had used to have one of those illuminated ceilings with a standard 2x4 LED troffer placed where one of the plastic diffusers would be with the original lighting disconnected. I lifted one of the remaining diffusers up to see the original lighting was two F40T12 shoplights (I think Lithonia), one fully intact with a pair of Philips F34/F40T12 Altos and the other missing its reflector and lamps revealing an early 1980s Advance 2x F40T12 magnetic RS ballast, which is probably where the power for the LED troffer is being fed from.