Self-luminous tritium exit signs do not need batteries or electricity for illumination. An isotope of the element hydrogen, tritium gas has one proton, two neutrons and is naturally present in the atmosphere. These exit signs use the electron from the tritium to provide illumination without the need for a source of electrical power. You will not see the tritium lamps when the normal lighting is on in the building. However, the sign becomes very visible when the power has gone out.

Exit signs in public buildings show the way out, and are mandated by the existing fire regulations to tell people where they must go to get out of their workplaces in the event of an emergency. Most exit signs around the world use the pictogram variety, with or without the text supplement.

The first “EXIT” sign was almost certainly black paint on a white wall. Light-emitting diode (LED)-based designs have replaced incandescent or fluorescent technology as the dominant electrical product. Photoluminescent and tritium products have become progressively more competitive, offering installation ease, flexibility and zero direct energy consumption.

The most important thing about modern exit signs is that they all include a graphic symbol. Signs are required to bear a picture or symbol that clearly illustrates the sign under the United Kingdom Health and Safety Regulations 1996. Signs that do not include this symbol and simply have words on them are now no longer legal, and need to be updated.

Although modern exit signs are not required to have any words, we suggest you use suitable wording to help people understand what the sign means. The European Standard sign is preferred and more readily available, but you can also use the British Standard sign. It is now a requirement in many countries that all new commercial buildings include well-marked emergency exits.

An evacuation may be necessary at any time in any workplace. To stay in conformity with the Fire Safety Order and to protect your workers, all exits must be plainly shown with very evident exit signs, particularly in areas where a way out is not very noticeable. Good signage helps make your workers conscious of possible dangers in the workplace, and can even help save a life in the event of a crisis.

To start with, place a sign over every 'final exit' door, such as the main entrance or a fire exit door. Also, place signs over every exit door in each main room in the building.
Other signs might be necessary to tell people that they need to change direction or move along a corridor. In listed and other similar buildings, it might not be possible to fit exit signs because they will affect the historic features of the building. It might be acceptable to use temporary signs for special events in these cases.

Signs may be propped over doors or fixed using small fixings that cannot be seen normally (such as small nails). In today’s world one of the hottest issues is how to move people in an urgent situation quickly and in safety to a secure refuge. Office buildings often have floor plans on display showing exit paths in red and regular hallways in black. Signs must not be too high and need to be plainly seen in the room.

The purpose of exit signs is to guide people to the closest exit in case of fire or other emergency. Most fire codes require exit signs to be permanently lit. With the development of fluorescent lamp and LED technology, exit signs could be made even brighter to show up in the limited visibility of a fire situation, while using less electricity. Tritium and phosphorescent signs have also been developed in recent years, and these require no electricity.