Emergency Lighting System Design Guide

This guide should be read in conjunction with current standards.

LEGISLATION CHANGES AND REQUIREMENTS

The British Standard BS5266 has been revised to conform with the European Standard EN1838 (issued in the UK under reference BS EN1838/BS5266 Part 7) which specifies luminous requirements for emergency systems installed in premises. It also now calls up the luminaire product standard BS EN60598-2-22: 1999.

Emergency lighting is provided for use when the supply to the normal lighting fails and is therefore powered from a source independent of that supplying the normal lighting. For the purposes of this standard emergency lighting is regarded as a generic term of which there are a number of specific forms.

NORMATIVE REFERENCES

EN 60598-2-22, Luminaires – Part 2-22: Particular requirements – Luminaires for emergency lighting.

(IEC 60598-2-22: 1997, modified).

prEN 50172, Emergency escape lighting systems.

ISO 3864: 1984, Safety colours and safety signs.

EMERGENCY ESCAPE LIGHTING GENERAL

To provide visibility for evacuation purposes lighting is required in the volume of the space. In this standard the recommendation is filled by the mounting of luminaires at least 2m above the floor. 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 direct sight of an emergency exit is not possible, an illuminated directional sign (or series of signs) shall be provided to assist progression towards the emergency exit.

An escape lighting luminaire complying with EN 6059~2-22 shall be sited to provide appropriate illuminance near each exit door and at positions where it is necessary to emphasise potential danger or safety equipment. The positions to be emphasised shall include the following (see opposite page):

• At each exit door intended to be used in an emergency;
• Near stairs so that each flight of stairs receives direct light;
• Near any other change in level;
• Mandatory emergency exits and safety signs;
• At each change of direction;
• At each intersection of corridors;
• Outside and near to each final exit;

The following positions if not on the escape route or in an open area shall be illuminated to 5 lux minimum on the floor.

Near (see note) each first aid post;

Near (see note) each piece of fire fighting equipment and call point.

NOTE: For the purposes of this clause, near is normally considered to be within 2m measured horizontally, subject to photometric data.

ESCAPE ROUTE LIGHTING

• For escape routes up to 2m in width, the horizontal illuminances on the floor along the centre line of an escape route shall be not less than 1 lx and the central band consisting of not less than half of the width of the route shall be illuminated to a minimum of 50% of that value.
• The ratio of the maximum to the minimum illuminance shall not be greater than 40:1 along the centre line of the escape route.
• Disability glare shall be kept low by limiting the luminous intensity of the luminaires within the field of view.
• The emergency escape route lighting shall reach 50% of the required illuminance level within 5s and full required illuminance within 60s.

OPEN AREA (ANTI-PANIC) LIGHTING

• The horizontal illuminance shall be not less than 0,5 lx at the floor level of the empty core area which excludes a border of 0,5 m of the perimeter of the area.
• The ratio of the maximum to the minimum anti-panic area lighting illuminance shall not be greater than 40:1.
• Disability glare shall be kept low by limiting the luminous intensity of the luminaires within the field of view.
• The anti-panic area lighting shall reach 50% of the required illuminance within 5s and full required illuminance within 60s.

Compliance can be checked by measurement or by comparison with authenticated data from a supplier. (ie third party verified)

STANDBY LIGHTING

• When standby lighting is used for emergency escape lighting purposes it shall comply with the relevant requirements of this standard.
• Where a standby lighting level lower than the minimum normal lighting is employed, the lighting is to be used only to shut down or terminate processes.

HIGH RISK TASK AREA LIGHTING

• In areas of high risk the maintained illuminance on the reference plane shall be not less than 10% of the required maintained illuminance for that task, however it shall be not less than 15 lx. It shall be free of harmful stroboscopic effects.
• The uniformity of the high risk task area lighting illuminance shall be not less than 0.1.
• Disability glare shall be kept low by limiting the luminous intensity of the luminaires within the field of view.

VERIFICATION OF LUMINAIRE PERFORMANCE

• Illuminance levels should be checked, either by taking measurements or by calculation from authenticated. The data is usually presented in the form of spacing tables.
• Light output from signs and or exit boxes shall not be considered unless verified photometric data is available.
• For mains lighting luminaires converted for emergency use, the organisation responsible for the conversion should provide photometric data.
• Luminaire performance will be adversely affected by the build-up of dirt and inadequate maintenance.
• Existing luminaires should be checked to ensure lamps and lighting controllers are clean, undamaged and not blackened.
• Luminaire markings should be checked to establish certification marking and ambient temperature limits, as well as any stated IP rating of the luminaire.

ROUTINE SYSTEM TESTING

• All emergency lighting systems should be regularly inspected and tested. Results obtained and details of any corrective action should be entered into a log book which is held on site. An appropriate printout of computer data from an automatic testing device also meets this requirement.
• Test procedures in accordance with the recommendations of the Fire Precautions (Workplace) Regulations and the code of practice.
• Risk assessment of an existing installation should include a full system test and the results should be entered on assessment sheets.

When carrying out a test, simulating a mains failure, safe procedures must be followed:

• Do not switch off other essential services or equipment.
• Do not fully discharge a system if the building has to be re-occupied before recharge is completed (typically 24 hours).
• Do not test by removing fuses – this practice is not acceptably safe. Purpose designed test switches or systems should be utilised.

EMERGENCY LIGHTING DESIGN PROCEDURES

CARRY OUT A RISK ASSESSMENT TO DETERMINE REQUIREMENTS

• Verify escape routes.
• Establish position of fire alarm call points and fire fighting equipment.
• Establish position of fire and safety signs.
• Investigate potential hazards on escape routes.
• Establish open areas.
• Establish requirements for external escape lighting.
• Locate lifts, moving stairways, toilets, control rooms, covered car park.
• Investigate need for standby lighting.
• Establish areas of low risk for location of central power system.
• If a central battery unit is used, please ensure there is adequate space, ventilation and at least one self contained emergency light located to give adequate illumination of the unit in the event of an emergency.

DESIGN OF ILLUMINANCE

• Position emergency lighting on plans to cover points of emphasis.
• Verify mounting heights of illuminaries.
• Investigate possible deterioration of luminaire light output due to dirt and dust.
• Check voltage and possible voltage drop.
• Determine mode of operation.
• Choose emergency lighting luminaires.
• Obtain detailed photometric data of luminaires complying with the requirements of BS5266 Pt 7:9999(EN 1838).
• Design scheme to the minimum illuminance required by the EN.

SAFETY SIGN REQUIREMENTS

Safety signs for emergency escape and first aid signs shall meet the following requirements.

• Safety signs shall be illuminated to at least 50% of the required luminance within 5s and full required luminance within 60s.
• The colours shall conform to the requirements of ISO 3864.
• The luminance of any area of safety colour of the sign shall be at least 2 cd/m2 in all relevant viewing directions.
• The ratio of the maximum to the minimum luminance within either white or the safety colour shall be not greater than 10:1.

All signs must be of the same type within a building and not mixed.

TYPICAL DESIGN CONSIDERATIONS

“Near” is defined as 2 metres horizontally within BS5266 subject to photometric data.

Please contact your local Sales Engineer or our Petersfield Service Centre for a free of charge Design Service.