Emergency exit lighting requirements for buildings are defined by standards provided by the National Fire Protection Association, Underwriters Laboratories, and the American National Standards Institute. These organizations list a variety of documents that provide minimum requirements for equipment to function both during an emergency and during normal operation. Such standards are available for a multitude of things, but those for emergency exit lighting are important because they ensure that people can get safely out of a building fire, for example.
Identification
Requirements for emergency lighting, as defined by the National Fire Protection Association, state that emergency illumination must be provided for at least 1½ hours after normal lighting fails. Illumination must be at least 1 foot-candle brightness, according to standard NFPA 101, Life Safety Code 2006, section 7.9, and be a minimum of 0.1 foot-candle at any point along an egress path along the floor. Also, the emergency lighting system must activate automatically.
Types
Based on Underwriters Laboratories' FTBR.GuideInfo document, emergency lighting product types include luminaries, exit signs, inverters, central station battery systems, load control relays and other products that enable these systems to operate. Electrical ratings, lamp compatibility and wiring diagrams must be marked on the charger/inverter packs or their instructions. Additional UL standards include those for retrofitting exit signs, using lighting/power equipment intended for marine vessels and equipment that can transfer use of normal power to emergency supplies and back when needed.
Expert Insight
Emergency lighting load control relays are important components that ensure the brightness of emergency lighting along a predetermined emergency path meets the required minimum levels when needed. LCRs also ensure that lighting circuits can be controlled during normal operations. An LCR, though, does not switch power loads between normal and emergency supplies, a task designated to transfer switches listed in accordance with UL 1008, Standard for Safety for Transfer Switch Equipment.
Function
The National Fire Protection Association has ruled that exit signs must display letters at least 6 inches high, with each letter's lines being at least ¾ inch wide. If the direction of travel to a nearby exit is not apparent, then an exit sign must have an arrow designating the direction to the exit. Signs can be externally illuminated, incandescently or fluorescently; internally illuminated by incandescent, fluorescent, electroluminescent, or lit by LEDs; or photoluminescent, meaning it has independent, self-contained power sources.
Considerations
The basic standard used to certify emergency exit lighting products is ANSI/UL 924. This standard, last revised in January 2009, applies to emergency lighting and power equipment. All the systems certified under this standard are intended to be connected to branch circuits of 600 volts or less. The standard also applies to equipment used in unclassified locations, which has not been investigated to determine compliance with NFPA 70 requirements, or those of NFPA 101 or the International Building Code.
Tags: emergency lighting, exit lighting, exit signs, Fire Protection, Fire Protection Association, National Fire, National Fire Protection