Emergency Lighting and Signage One of the fundamental requirements of fire safety and fire safety legislation is to ensure that persons within the building can evacuate safely in the event of an emergency. Overriding all these factors is the usability of the escape route when required. This relies on occupants of the building being able to find the escape route and, as far as possible, safely traverse the route to a place of safety. It is inappropriate to depend on natural lighting as not all emergencies occur during daylight hours, also many buildings are not properly lit internally by daylight. Main lighting power can be lost during a fire and the cable serving the lighting circuits may be destroyed, the electrical system may also be 'isolated' or turned off to remove the threat of electrocution. For this reason, a lighting system should be available in an emergency such as in the event of a fire. The requirement for emergency lighting, its type and location, is defined through the carrying out of a risk assessment. Definitive information and specifications for emergency lighting systems will be subject to the requirements of relevant national or international legislation or standards. Examples include: • BS EN 50172:2004: Emergency escape lighting systems (UK) • NFPA Life safety code (101) • OSHA 29 CFR:1910 • AS 2293.1-2005, AS/NZS 2293.2:1995 and AS 2293.3-2005. (Australia) Emergency lighting units should be sited to cover specific areas, such as intersections of corridors, at each exit door, and near each staircase so that each flight of stairs receives direct light, close to a change in floor level outside each final exit. Also, close to firefighting equipment and fire alarm call points, by exit and safety signs that are required elsewhere subject to the risk assessment. Two categories of emergency lighting systems are available: maintained, and non-maintained. Maintained emergency lighting is always on. The emergency lights are mains powered and used as part of the normal room lighting system. However, in an emergency when mains power fails, it will continue to stay lit for a specific duration powered by a backup battery. Non-maintained emergency lighting usually only comes on for a specific duration when the power supply to normal artificial lighting fails. The lighting is powered by a battery that is charged from a constant trickle of mains power. This battery should have enough charge to remain lit for a duration of 3 hours or more if mains power fails. The Emergency escape lighting (EEL) should be located at mandatory 'Points of Emphasis' to reveal specific hazards and ensure that escape routes are clearly identified, the illumination along escape routes is sufficient to allow safe movement towards the final exits and to ensure that fire alarm call points and firefighting equipment can be readily located. Emergency generators may be used to maintain the lighting system in case of a mains failure. They may run on fuel such as petrol or diesel, which would be stored on the premises. Emergency generators should be able to start automatically in the event of a power failure. They should also have a suitable supply of fuel for that period, and have their own cooling water, air supply and exhaust gas emission route.
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