Egress Lighting Requirements for the Life Safety Code
The National Fire Protection Association's Life Safety Code provides a model set of building regulations to assist regional laws in ensuring maximum safety and practicality. Lighting systems must meet standards set by the Life Safety Code, particularly during egress, or exit, in times of emergency. In cases where the main power supply is compromised, the Life Safety Code requires that an alternate source power the egress lighting.
General Light Level
According to sections 126.96.36.199 through 188.8.131.52 of the Life Safety Code, light fixtures must illuminate all of the walking surfaces, including floors, stairs or landings, to a brightness of at least 1 footcandle, with the light intensity measured at the height of the floor. A footcandle corresponds to roughly 1 lumen of light, equally distributed across a surface measuring 1 square foot. The term originally referred to the light given by one candle, burning at a distance of 1 foot from the illuminated surface.
In case of a power loss, the emergency lighting system must continue to provide adequate lighting for a length of time sufficient for any necessary evacuation. According to section 184.108.40.206, the emergency lighting must continue for at least 1 1/2 hours after the regular light source fails.
Average Light Level
While the Life Safety Code indicates a minimum illumination of 1 footcandle, measuring along the floor, its section on "Performance of Systems" further defines the minimum illumination, taking an overall average into consideration. The egress path illumination level must average at least 1 footcandle. At any given point along the path of egress, the floor must be illuminated to at least .1 footcandles. By the end of the 1 1/2 hours, the illumination levels must not have diminished to any less than .6 footcandles overall and .06 footcandles at any given point. The overall illumination must be relatively uniform as well, with the brightest point no more than 40 times as bright as the darkest point.
In addition to the NFPA Life Safety Code, a number of other model codes and code-making organizations set regulations for egress lighting. The Occupational Safety and Health Administration (OSHA) considers those employers who comply with the means of egress regulations of the Life Safety Code to fulfill their own egress lighting requirements. The Uniform Building Code, used as a model building code in some areas, varies from the Life Safety Code in that it requires a minimum illumination of 1 footcandle. This requirement is sometimes interpreted as necessitating this brightness at any given point, and not merely as an average.