Photoluminescent Exit Signs vs. Tritium Signs
There are two reasons to choose an illuminated exit sign over an electrical exit sign: it costs less to operate, and it offers greater safety in the event of emergency evacuations. In terms of cost savings, an illuminated exit sign—also known as a luminescent exit sign—is superior to electrical signs for two reasons: it uses no electricity, and it requires no maintenance. Concerning evacuation safety, luminescent signs offer a greater safety due to their higher visibility in the presence of thickening smoke and their lack of parts that could break in the event of falling debris, as might happen during an earthquake.
The superior safety of luminescent exit signs is supported by the International Fire Code (IFC), which governs the egress safety of new and existing commercial and residential R1 buildings that contain occupancy at above 75 feet from the lowest level of fire department vehicle access. Among its egress regulations, the IFC calls for illuminated exit signs to indicate official building exits, which leaves building owners in IFC compliant states with two options: implementing photoluminescent exit signs, or implementing Tritium exit signs. However, when the signs are compared for cost value and overall safety, photoluminescent signs emerge as the better choice.
Photoluminescent signs are powered by photoluminescence, which occurs when an object absorbs photons (i.e. ambient light) from its surroundings and re-emits them, creating a bright glowing effect. Tritium signs, on the other hand, are powered by radioactive capsules, which result in a $75 disposal fee unless a spent Tritium sign is returned to the manufacturer under the agreement to buy a new sign. While the radioactive capsules that power Tritium signs are contained within shockproof casing, there have been instances of their breakage, which necessitates the attention of a radioactive clean up crew.