Hazardous location exit signs and emergency lights are designed to operate in hostile environments that would damage ordinary signs and lights. Constructed from corrosion resistant materials, some units offer sealed enclosures that can be used in outdoor environments or areas subject to water spray or moisture.
The need for hazardous exit signs or emergency lights is not always just for the protection of the units themselves, but for that of those who might be in the vicinity. For example, Class I Division II fixtures are designed to function in areas where flammable gases or vapors and/or combustible dust exist. In these types of environments, an "every-day" fixture could accidentally ignite an explosive reaction. Specialized emergency lights and exit signs are designed specifically for their rated environments, and should always be installed in hazardous locations.