A nuclear powered Exit sign. Uses Tritium gas inside glass tubes that glow like a fluorescent lamp. The radioactive Beta particles exite the phosphor inside the tube, but too weak to penetrate the glass tube.
these probably aren't common..I've never seen one! and it looks like it's not working or just too dim to be seen with other lights on but in the dark might be visible?
This is (or was) once a tritium self-illuminating exit sign but a closer look at it reveals that the face was overlaid (or replaced) with a photoluminescent exit sign card which glows in the dark after being exposed to light for a while. Note the "Minimum 5 footcandles of fluorescent illumination" notice across the bottom.
I know there are four Tritium Self-Illuminating exit signs at my church which have been there since they built it in 92. The border is solid with the word "<EXIT>" cut out and a prismatic diffuser behind the letters to spread the light from the tubes. It glows a faint green color in a dark room.
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I know there are four Tritium Self-Illuminating exit signs at my church which have been there since they built it in 92. The border is solid with the word "<EXIT>" cut out and a prismatic diffuser behind the letters to spread the light from the tubes. It glows a faint green color in a dark room.