Recommended Light Levels for Emergency Lighting

Description

• Emergency lighting has two varieties. One kind lights up exit doors and other means of egress. Such lighting must always be on whenever a building is occupied. The other comes on to provide temporary illumination when the power goes out. Both types provide a safe path for leaving a structure during an emergency such as a fire. As such, they need a source of temporary power that allows occupants to exit for a specified period of time. Emergency lighting is required in commercial, industrial, government and other public spaces but is optional in one- or two-family residences.

International Building Code

• Local and state building codes define the standards for emergency lighting, which are based on broader standards. One such standard is the International Building Code, or IBC, which is managed by the International Code Council. It recommends an exit illumination level of at least 1 foot candle or 11 lux at the walking surface. For assembly areas such as auditoriums, theaters or concert halls, illumination can go down to 0.2 foot candles or 2.15 lux but only if the required illumination activates during an emergency, such as when the fire alarm sounds.

Power

• The IBC also defines power for emergency lights as lasting at least 90 minutes, with the help of storage batteries, an on-site generator or unit equipment. Several areas of a structure require lighting at the recommended levels. They are aisles and exit stairways with two or more exits; interior and exterior exit areas in buildings required to have two or more exits; and exterior landings in buildings that require two or more exits.

Others

• Another source for emergency lighting recommendations is the Life Safety Code of the National Fire Protection Association. It states that the minimum illumination is also 1 foot candle as measured on the floor, and that emergency lighting is needed for at least 90 minutes after normal lighting fails. Any such lighting, however, needs to provide initial illumination of a minimum of 0.1 foot candles as measured along the exit path at floor level. The average must be at least 1 foot candle. Lighting can decline to 0.6 foot candles average, with a minimum of 0.06 foot candles near the end of the emergency lighting time. The uniformity ratio between minimum and maximum must be less than 40-to-1.