The safe route to emergency lighting

GILES LILLISTONE, Technical & Quality Manager at GreenBrook Electrical talks about emergency lighting and the requirement for successful installation and testing…

Every building has a specific requirement for emergency lighting, the role of which is to take over from the normal lighting provision in the event of a power failure. Lighting requirements will vary within each building, as rooms without the benefit of daylight must always have lighting provided. Similarly, if a building is occupied at night, there should be emergency lighting installed in all areas, including those lit naturally during the day.

It is now considered that emergency lighting is a primary factor in fire safety and should enable occupants to immediately locate fire-fighting equipment and alarms. Emergency lighting installations are examined as part of a building’s overall fire precautions risk assessment.

Emergency lighting is a general term and is subdivided into ’emergency escape lighting’ and ‘standby lighting’. Standby lighting is the part of emergency lighting that enables normal activities to continue in the event of failure of the normal mains supply.

The difference between these is that whilst emergency lighting forms part of the fire protection of a building, standby lighting does not.

Positioning of emergency lighting

Emergency escape lighting should illuminate the following:

• Each exit door (where the exit route or final exit is not readily identifiable or familiar to the occupants, a sign should be used with a pictogram of the person moving towards the doorway, rather than just a lighting unit)

• Escape routes

• Intersection of corridors

• Outside each final exit and on external escape routes

• Emergency escape signs

• Stairways ensuring each flight receive adequate light

• Changes in floor level

• Windowless rooms and toilet accommodation exceeding 8m²

• Fire-fighting equipment

• Fire alarm call points

• Equipment that would need to be shut down in an emergency or a high risk task area

• Lifts

•Areas in premises greater than 60m²

A sufficient overall level of light is required to allow all of the above items to be visible and usable – it is not necessary to provide individual luminaires for each item listed.

Maintained or non-maintained?

Emergency escape lighting can be both ‘maintained’, i.e. on all the time, continuing to operate in the event of a power failure, or ‘non-maintained’, a system that only operates when the normal lighting fails. These units are designed to operate for durations of greater than three hours after the mains power supply fails.

Non-maintained operation is generally the most popular choice, being cheaper in terms of energy consumption and the life span of the fitting. However, in some premises where the luminaires are always “on” i.e. in maintained mode, such as theatres and cinemas, there is sometimes no choice in the matter.

A disadvantage of non-maintained variants is that the condition of the lamp can only be established through regular testing; it’s no good waiting for a power cut to discover it isn’t working!

Emergency luminaires are also available as signs; a typical example is the pictogram of the person moving through or towards a doorway, with a directional arrow. Others may use text, e.g. ‘Fire Exit’. These units are available in both maintained and non-maintained versions in a range of styles, from the simple box type through to the slimline hanging sign. Pictograms and pictograms with text should not be mixed in the same premises.

More options…

There are two main types of luminaire, the relevant standard for which is BS EN 60598-2-22: self-contained and centrally supplied.

The self-contained luminaire contains all the essential components (i.e. battery, charger, control unit, lamp, diffuser and any test or monitoring facility) for it to function as an independent emergency light. This is the most common form of emergency lighting and is typically supplied as a surface-mounted, rectangular bulkhead luminaire, although a wide range of self-contained luminaires are available.

Centrally supplied luminaires, or ‘slaves’ (because they cannot function independently), are defined by BS EN 60598-2-22 as follows: “luminaire for maintained or non-maintained operation which is energized from a central emergency power system that is not contained within the luminaire”. Slave fittings contain the lamp and some of the control gear but the charger, battery and often the changeover device are located remotely and provide the supply to a number of luminaires.

Illumination

The degree of illumination required should be closely related to the nature of both the premises and its occupants, with special consideration required for care homes, hospitals, crowded venues like pubs, nightclubs etc, and to whether the premises has overnight accommodation.

In areas of high risk (operating moving machinery or vehicles, a kitchen or chemical area) the maintained illuminance should not be > 10% of the required maintained illuminance for the task. This will be subject to a minimum illuminance of 15lux. The minimum duration is the period for which the risk exists to people.

All emergency luminaries should meet the lumen output specified by the manufacturer to ensure any areas that needs emergency lighting are well lit. Choosing illumination with features such as refractive optics that provide high and uniform light levels ensure clear vision.

Testing

Legislation clearly states the requirements of testing emergency lighting units. Regular checks ensure that all users have sufficient illumination in the event of an emergency.

Testing should include:

• a daily visual check of any central controls if a centrally powered system with slave luminaires is installed;

• a monthly function test by operating the test facility for a period sufficient to ensure that each emergency lamp illuminates; and

• an annual full discharge test to ensure that the lamps are lit for the full discharge period (usually 3 hours) and that the batteries are re-charging

A typical test is using a key operated switch that is located either near the main fuse board or adjacent to relevant light switches. This is also known as a ‘secret key’ switch, as it is designed to allow testing of emergency lights while preventing non-authorised operation of the test switch.

Following a full discharge test the batteries typically take 24 hours to re-charge. The premises should not be re-occupied until the lighting system is fully functioning.

It is best practice to keep a record of all tests in the safety/risk assessment logbook.

Way-guidance equipment complements emergency escape lighting, especially for those occupants unfamiliar with the premises to help identify exit routes. This comprises of photoluminescent material, lines of LEDs, or strips of miniature incandescent lamps, forming a continuous marked escape route at floor level. These systems have proved particularly effective when people have to escape through smoke, and for partially-sighted people.

LED emergency lighting

With increasing focus on energy saving, LED is becoming the popular choice for emergency luminaires. The lamps start up instantly giving an additional bonus against some other types of low energy lamps, plus LED’s are smaller so can be used in more stylish designs.

New emergency fittings come complete with an auto testing feature which can be cost effective and more reliable than manual testing. It’s considered the best way to meet current testing regulations and reduces the burden of testing manually.

Even though emergency lighting is a legal requirement, we can now choose a variety of styles from downlights to bulkheads to ensure the fitting is in keeping with its surroundings.

GreenBrook offer a selection of twin spots, downlights, bulkheads, exit signs, recessed lights and emergency gear trays with LED options.

www.greenbrook.co.uk