Yep, but napervillesoundtech definitely had two 240V bulbs series wired to 120V. Pretty dim I guess.
I think the non-electric exit signs I've seen here are photolumiscent rather than radioactive. They're basically flat sheets of some kind of plastic stuck to the wall.
A friend of mine had radioluminiscent paint dating back to WWII in his basement until very recently... now that was cool! Only white walls as long as the lights were on, but in the dark you'd suddenly see a glowing green horizontal line maybe 5 feet from the floor and the word "Ausgang" (Exit) in some script writing painted next to the door.
