- 1). Locate and open the fuse box for the building. Identify the fuses associated with the room the exit sign is in and the main fuse. Turn off the power to the room then check the sign. If it is illuminated, go back and turn off the main power switch and check the sign again. If, after turning off the power, the sign does not illuminate, the sign is hard wired to your electricity and is not a tritium exit sign.
- 2). Check for wires leading from the exit sign to a series of photovoltaic cells (flat, thin glass-covered rectangles that function as solar cells). A series of photovoltaic cells may be set up in a place with maximum sun exposure or built right onto the exit sign frame. In either instance, your exit sign is solar-charged, not tritium-powered.
- 3). Look for screws in the metal backside of the exit sign. If your sign can be read from both faces, look for screws set into the metal side frame of the sign. If you see four screws, your sign is battery-powered, not tritium.
- 4). Read the label on the exit sign. All exit signs are required to carry a label that lists their voltages and manufacturing information. A tritium-powered exit sign will also carry the international symbol for radiation. If you see this symbol, there is no question that your exit sign contains tritium.
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