Emergency lighting

In the event of power supply failure, emergency lighting will provide essential temporary illumination, as required by several key health and safety regulations

by Paul Caddick

25 November 2010

 

As the Health and Safety Executive states: “Employers have a general duty under section 2 of the Health and Safety at Work Act 1974 to ensure, so far as is reasonably practicable, the health, safety and welfare of their employees at work”. Fulfilment of this duty and section 4 of the Act requires a range of provisions and one key area is emergency lighting. Knowing what lighting must be provided, tested and maintained 
is therefore essential for any 
duty holder.

Like most essential provisions in the workplace, legislation for emergency lighting begins with the Health & Safety at Work Act 1974. Added to this act are specific regulations such as The Workplace (Health, Safety and Welfare) Regulations 1992, which cover a wide range of basic health, safety and welfare issues and apply to most workplaces. They cover not only the employees of an organisation, but also the people who use the premises.

Other regulations also cover aspects of emergency lighting, for example, The Building Regulations 2000 detail the requirements for new buildings and major refurbishments and The Fire Precautions (Workplace) Regulations 1997 state that “Emergency routes and exits requiring illumination must be provided with emergency lighting of adequate intensity in case the lighting fails”.

In practice, the guidance on how to deliver against these regulations comes from the British Standard BS5266 Part 1 2005, the Code of Practice for Emergency Lighting.

Emergency Lighting Essentials
The Workplace (Health, Safety and Welfare) Regulations 1992 state that automatic emergency lighting, powered by an independent source, should be provided where sudden loss of light would create a risk. Clearly, it is vital that emergency lighting comes on if other lights fail as in the case of an emergency and that the light provided is sufficient and sustained so that the people in the premises can be safely evacuated. Therefore, consideration must be given to:

● The provision (the system)
● Light output (measured in lux)
● Its reliability and sustainability (fail-safe operation and duration of continued operation)
 
Provision
The purpose of emergency provision is detailed in BS5266 as to fulfil the following functions:
● To indicate clearly and unambiguously the escape routes
●    To provide illumination along such routes to allow safe movement towards and through the exits provided
●    To permit operations concerned with safety measures
●    To ensure that fire alarm call points and fire fighting equipment provided along escape routes can be readily located

There are three main types of systems for emergency lighting; non-maintained, maintained and sustained. Non-maintained operates only in the event of mains failure. Maintained operates all the time the building is occupied and sustained operates all the time on mains power and then, like non-maintained, uses battery power in the event of mains failure.

Light Output
Critically, the emergency illumination provided should be appropriate to the type of premises and its occupants. BS5266 recommends horizontal illumination of not less than 0.2 lux at floor level on the centre line of a defined escape route and 0.5 lux minimum for anti-panic areas. For escape routes of up to 2 metres wide, 50 per cent of the route width should be lit to 0.1 lux minimum.
 
Reliability and Sustainability
The required operating duration for emergency lighting varies according to the type of system. From a minimum of one hour for a sustained system, two hours for a non-maintained system and three hours for a maintained system.

The Fire Precautions (Workplace) Regulations 1997 recommends that continued maintenance and testing must be correctly carried out. This typically means annual testing to simulate mains power failure, forcing the emergency lighting to operate and use its emergency power supply. This test must check the satisfactory operation of each luminaire for a duration appropriate to the type of system and establish that the light output is sufficient to meet standards requirements.

Battery life should also be checked and once mains power is restored the engineer should check that all batteries are recharging.

For safety, emergency lighting testing or ‘discharge tests’ should be carried out in unoccupied premises or unoccupied portions of those premises. In permanently occupied buildings it is recommended that testing is phased so that every other luminaire is tested.


Testing tips

● 
When emergency lighting is tested the engineer will create emergency conditions by simulating mains power failure
● 
The emergency light must then provide illumination that meets the output lux levels recommended in BS5266
● 
For this to be checked, the engineer will require a light meter
● 
In order to get an accurate measurement, ambient light should be discounted from the lux readings


Paul Caddick is managing director at safety compliance specialists PHS Compliance