Emergency lighting delivers light during a loss of mains power, using either independent fittings with their own batteries or emergency lighting circuits and a generator. Independent emergency lights are popular because they are quick and cheap to install. They benefit from not being linked by the same central power supply or wiring, eliminating the risk of multiple lights being disabled by a single failure.
Emergency lighting categories
There are two main categories of emergency lighting: escape lighting and standby lighting. Of these, escape lighting should be the primary focus of any lighting specifier or installer. It has the potential to save lives in the event of a fire. Standby lighting allows normal work to continue after a power failure, but does not form part of a building’s fire protection.
Escape lighting is divided into three sub-categories, as follows:
- Escape route lighting plays the vital role of enabling quick evacuation of a building. Included in this category are green exit signs with pictograms or pictograms and text (the two styles should not be mixed). Also emergency ceiling or wall lights that provide a minimum 1-lux light level along the centre line of escape routes (e.g. the centre of a corridor floor).
- Open area lighting must include emergency fittings if the floor area is larger than 60m². This is to prevent panic in places where people are likely to congregate and is sometimes called ‘anti-panic’ emergency lighting. Smaller areas are also counted as open area lighting, such as toilets (above 8m² and all disabled toilets), escalators, and lifts.
- High-risk task area lighting ensures that task areas remain illuminated that would cause imminent danger to life if abruptly darkened. Examples include hospital operating theatres or wards and control rooms in dangerous plants or production facilities. A minimum 10% of normal lighting levels must be provided by emergency lighting in these areas, or a 15-lux minimum if this value is higher (the former is more likely).
Lux is an SI unit that measures the intensity of incident light on a surface. It is directly affected by the distance between the surface (e.g. floor or desk) and the light source.
Points of emphasis
Critical areas or features of an escape route are called ‘points of emphasis’, with each point requiring emergency lighting. They include the following:
- Emergency exit doors
- Exit and safety signs
- All flights of stairs
- Changes in floor level
- Changes of direction
- Intersections of corridors/escape routes
- Fire alarm call points
- First aid posts
- Firefighting equipment
- Outside and near (within 2m) each final exit
Maintained v non-maintained emergency lights
A maintained emergency light is used as part of an overall lighting scheme and stays switched on in the event of a power cut. A non-maintained light is kept switched off, but activates automatically during a power cut. Both types of fitting include a battery, which allows up to 3 hours of back-up lighting.
Maintained exit signs are a necessity in public buildings and entertainment venues, where occupants are less likely to be familiar with escape routes. Non-maintained exit signs are common in private workplaces.
LED leads the way
LED emergency lights are being increasingly used in place of fluorescent equivalents, which were the main emergency light source for years. LED technology has been improved to such a degree that it excels in most applications. It is often 30 to 50% more energy efficient than fluorescent lighting and has a long lifespan of up to 50,000 hours. A fluorescent lamp might only last 6,000 hours before it abruptly fails.
Other LED benefits include instant full power light with no warm-up time (useful in emergency lighting), resistance to vibration and shock, and reliable cold temperature performance down to about -20°C.
Maintained emergency lights benefit most from LED longevity because they are used for several hours a day. With ceiling lights, you’ll usually be able to buy standard fittings from the same range, so you can blend your emergency luminaires seamlessly into an overall lighting scheme.
A non-maintained light fitting sometimes benefits from a discreet design, since it does not function as part of an everyday lighting scheme. The Daylight LED Emergency Light capitalises on the compact size of LEDs. This tiny fitting easily surpasses typical escape route requirements and because LED lighting is naturally directional, it is able to focus light of sufficient intensity along escape routes with minimal loss of light or use of battery power.
The Eterna IP65 LED Twinspot Emergency Fitting is a non-maintained wall fitting that is ideal for lighting walkways in high-bay warehouses and industrial areas. Its IP65 rating also allows use along outdoor escape routes leading to safety points. Again, the directional nature of LEDs means very little light is spilled in spotlighting applications.
Installation of an emergency lighting system requires compliance with the following British Standards:
- BS 5266-1:2011 (Code of practice for the emergency escape lighting of premises)
- BS EN 1838:2013 (Emergency lighting)
- BS EN 50172:2004 – also numbered as BS 5266-8:2004 (Emergency escape lighting systems)
- BS 7671:2008 incorporating amendment number 1:2011 (IET Wiring Regulations 17th Edition)
An authoritative PDF guide to emergency lighting is downloadable from the ICEL (Industry Committee for Emergency Lighting) here.
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