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LEDs in an Emergency

10 September 2010

In a building emergency fast panic-free evacuation can easily make the difference between lifeand death. Bernard Pratley argues that the latest LED emergency lighting makes this easier to achieve with significant extra benefits for FMs

MOST PEOPLE UNFAMILIAR with a building tend to leave it the same way that they entered it, often ignoring shorter escape routes. Therefore, emergency lighting and escape route illumination must make it easy for those evacuating to see clearly enough to safely and quickly make their way out, using the nearest and shortest designated exit paths. Can the latest generation of white light LEDs help? The answer is 'yes'.
LED lighting has several benefits over conventional fluorescents that have been in emergency lighting luminaires for many years. For example, LEDs are energy efficient. Compared with equivalent fluorescents, good LED emergency exit signs and luminaires often show energy savings of 30 percent or more. The light can be much more focused to its purpose which will save significant costs over the installation's life. LEDs are small, so are usually clustered to provide sufficient light, reducing the energy efficiency to a degree. Even clustered, LED lighting is efficient and compact, but to achieve optimum LED lighting performance, dedicated control gear (drivers), optics and fittings are necessary. This is a significant benefit in itself, because there are exciting possibilities with sleek, modern and unobtrusive luminaire designs being possible.
LEDs are also very robust, have an excellent low temperature performance and are easily digitally controlled, but perhaps the most remarkable attribute of LED lighting is its long life. There are high quality products available that will operate for 50,000 hours or more, yet still provide 70 percent of the original light output.  This brings significant time and money-saving maintenance advantages for facilities managers, of which more later.
LEDs have been used in exit signs for about three years, but the technology has progressively improved to the extent that there are now LED equivalents for most conventional lamp types, with the cost reducing all the time. Therefore, LEDs are now also suitable for a wider range of emergency lighting luminaires. Typical is P4's Stairway LED system (right).
LEDs typically have a 60-degree beam, so when correctly installed at a three metre mounting height at recommended spacings, emergency lighting luminaires should have no trouble achieving 1 lux at the floor, using just two 1W LEDs, plus LED control gear, inverter and suitable self-contained battery for a three-hour duration.
Compliance with BS EN 60598-2-22, the emergency lighting luminaires standard, and EN50172 (BS 5266 series), the emergency escape lighting application standards, together ensure that there will be sufficient illumination for people to see and be directed towards emergency exits, with exit or directional signs being in view everywhere along the escape route. Note that BS 5266-1, the umbrella Code of Practice for emergency lighting, calls up the two relevant application standards: EN 1838/BS 5266-7, which covers lighting levels and also exit sign illuminance values; and EN 50172/BS 5266-8, which covers other areas such as testing frequencies etc.
Exit signs must be clear even at maximum viewing distances, according to application standard EN1838/BS 5266-7. The luminaire construction standard EN60598-2-22 defines minimum luminance levels that signs must attain in relation to viewing distances. LEDs help achieve this.
BS5266 Part 1 is currently being revised. This Code of Practise has, until recently, been treated as a prescriptive standard, but now the legal requirement is that non-domestic buildings must be safe at all times, even if mains power failure occurs. Therefore, nearly all such buildings must have emergency lighting fitted. However, any risks associated with individual buildings, established by a risk assessment to be carried out by owner/occupiers - which often involve FMs - must be 'limited to tolerable levels'. The one size fits all approach will no longer be sufficient; emergency lighting must now be targeted at individual buildings far more than used to be the case. For example, although BS5266 doesn't call for emergency lighting in small rooms, if the risk assessment shows a need for emergency lighting, then it should be fitted.
Maintenance
It will also no longer be adequate to 'fit and forget' emergency lighting; it must always be in full working order. Maintained emergency lighting and exit signs are ideal for best building safety, but not necessarily so from a maintenance perspective. This is because 8W fluorescent lamps in such applications have a typical working life of around 6,000 hours; if they are illuminated several hours a day, regular lamp replacement will be required. Here, good quality LED emergency lighting has a distinct advantage over traditional types because of its significantly longer life. Replacing lamps is always time consuming and costly, and often disruptive too, requiring access to fittings mounted along escape routes and above exits. Such areas often cannot be obstructed during working hours, necessitating costly out of hours working. In addition, there are the costs of lamp replacement and failed lamp disposal.
Therefore, there is no reason today not to use good quality LED emergency lighting products from reputable manufacturers. As a safeguard, purchasers could check that the products being installed have come from an Industry Committee for Emergency Lighting (ICEL) member. Monthly and annual testing of every luminaire is necessary, with central battery system indicators being visually inspected daily. All selfcontained emergency lighting must be functionally tested for 5-10 minutes minimum every month, and tested for full rated duration of typically three hours at least every year. Accurate records must be kept. In large buildings, this can be a lengthy job that may be impossible to achieve whilst keeping the building in a legal, fully working state.
Automatic testing solves these problems costeffectively by regularly checking, without human intervention, that emergency lighting batteries and luminaires are working correctly. The system generates reports automatically on any fault that requires remedial action. Test results still need to be recorded manually and logged, but the person recording does not spend time carrying out the tests themselves, and need not be electrically qualified. Even manual recording can be avoided by using automatic data collection.
The case is strengthened by the importance given to the correct functioning and proper testing of emergency lighting under BS5266-Part 10:2008, which also promotes automatic test systems to BS EN 62034. Automatic testing, therefore, can save much time and money, and the high responsibility of conventional testing is reduced - providing confidence. Some people take less care than they should over testing and maintenance; automatic testing largely obviates this.
ICEL believes, therefore, that automatic testing is more reliable than manual testing and can be more cost-effective, providing peace of mind into the bargain. Consideration should be given to installing automatic emergency lighting testing systems conforming to BS EN 62034 because of their reliability and costeffectiveness.
The reduced testing and lower labour costs compared with manual testing can provide real savings over time. Facilities managers can see even complex systems payback in two to four years.
ICEL provides specific training courses for Emergency Lighting requirements, suitable for designers, maintenance engineers and facilities managers.


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