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To ensure that emergency lighting is fit for purpose a combination of standards and regulations covers all aspects of its safety. Using a third party to certify a system is an effective way of helping to ensure quality, reliability and conformity.
A key element of the compliance landscape is the EN50172 standard. This sets out the requirements for emergency lighting when the supply to all or part of the normal lighting in occupied premises fails. It states that emergency lighting shall:
The EN50172 standard – which also applies to standby lighting used as emergency escape lighting – recommends that discussions should be held pre-design to establish the areas to be covered, method of operation, testing regime and most suitable system type. These discussions should include the owner or occupier of the premises plus the system designer, installer, equipment supplier and fire authority.
| Legislation (legal requirement) |
National fire safety legislation | |||
| Harmonised EU Application standards (shall) |
EN 50172 Emergency escape systems |
EN 1838 Lighting applications, emergency lighting |
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| Harmonised EU Protected standards (shall) |
EN 60598-2-22 Luminaires for emergency lighting |
EN 60235 Automatic test systems |
EN 50172 Central power supply systems |
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Time is of the essence during evacuation and this means it is critical that all escape route signage can be quickly seen, understood and followed. Section 4.1 of EN1838:2013 details this point stating that ‘Signs which are provided at all exits intended to be used in an emergency and along escape routes shall be illuminated to indicate unambiguously the route of escape to a point of safety’.
Where there is no direct sight of an emergency exit, an illuminated directional sign or series of signs must be provided to help people make their way to the emergency exit. The single pictogram format specified in ISO 7010 and adopted by many national standards bodies from 2011 onwards is current best practice.
Most countries have adopted pictogram style signs, or are in the process of updating local guidelines.
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| Recommended signage EN ISO 7010:2012 E002 |
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| Accepted signage |  |
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Legacy signs
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ESCAPE route sign colours are specified by ISO 3864 that:
Every system design must correctly locate luminaires to reveal specific hazards and highlight safety equipment and signs – known as points of emphasis – whether it is for an emergency escape route or open (anti-panic) area. The design must also take into account the type of luminaire needed and its light output as detailed by EN 1838: 2013 and EN 60598-2-22. The following representation highlights key points of emphasis requiring a luminaire:
The following representation highlights key points of emphasis requiring a luminaire:
Maximum viewing distances and luminance conditions are detailed for all safety sign formats in EN 1838: 2013. Signs can either be internally illuminated – such as exit boxes or edge-lit emergency luminaires with a screened sign that have a controlled illuminance – or be of a non-powered type.
While internally illuminated exit signs that meet EN 60598-2-22 are pre-tested to ensure compliance, extra care must be taken if the sign is designed to be externally illuminated. An emergency luminaire must be sited within 2 metres of the sign and the multiplication factor is only 100. The sign must be illuminated to a minimum lux on any part of its face in emergency conditions.
Once the points of emphasis have been covered, designers must consider if any additional luminaires are needed to ensure minimum illuminance levels so that routes can be used safely. Every escape route compartment must have at least two luminaires in case one should fail.
A minimum lux is required on the escape route centre line as detailed by EN 1838: 2013 4.2. A uniformity ratio of 40:1 maximum to a minimum must not be exceeded.
This illuminance must be provided for the full duration and life of the system. A % of the illuminance must be available within five seconds and full illumination must then be supplied within a specified time period following supply failure.
Authenticated spacing tables or a suitable computer program are used to determine whether luminaires are needed beyond those at points of emphasis to provide the minimum required level of illumination on escape routes.
To ensure that the design will meet the required levels at all times the data is ‘de-rated’ – as required by the standard – to take into account:
An ‘open (anti-panic) area’ is so defined if it is larger than 60m2, has an escape route passing through it or it features hazards identified by the building risk assessment. The current standard makes it straightforward to design and verify systems that provide good uniformity, rather than using a small number of large-output luminaires.
Light level requirements
A 0.5 lux minimum of the empty core area – which excludes a 0.5m border of its perimeter – is detailed by EN 1838:2013 – 4.3. Spacing table (example below) or a suitable computer program are similarly used to generate data. This is then de-rated in the same way as it is for escape route lighting to determine luminaire location.
Spacing data
Spacing tables provide photometric data which can be used to help ensure that the emergency lighting system has been designed correctly and meets the required illumination levels.
The risk assessment will identify any locations needing special consideration. For example, these might include plant and production lines deemed to be high risk or control rooms that manage dangerous processes.
For these high-risk areas, EN 1838: 2013 details that the maintained illuminance on the reference plane shall not be less than 10% of the required maintained illuminance for that task and never less than 15 lux.
Design implications
When designing for areas that require enhanced levels of emergency illumination, it’s important to consider all the options which may include converted mains lighting, self-contained or CBS-powered luminaires. In most cases, the solution will also have higher Ballast Lumen Factors (BLF).
Emergency response time is another critical factor for high-risk locations. This may require emergency luminaires to be operated in maintained mode or alternatively the use of tungsten projector units. Should the latter be chosen, it’s important to bear in mind the need to maintain a reasonable level of uniformity.
