CoP 0001 Issue 1.0 – Code of Practice for visual alarm devices used for fire warning
SCOPE
This Code of Practice gives recommendations for the planning, design, installation, commissioning and maintenance of facilities using VADs to give the primary warning of fire to certain persons in and around buildings, other than single-family dwellings.
This Code of Practice does not recommend whether or not VADs should be installed in any given premises, nor the areas in which they should be provided.
NOTE For the purpose of this Code of Practice it is assumed that a decision has already been taken to provide VADs.
This Code of Practice is intended to be used for VADs complying with BS EN 54-23. This Code of Practice does not apply to:
1) visual indicators installed in or around premises to give those responding to a fire alarm signal (e.g. the fire and rescue service) an indication of the location of the fire (e.g. visual indicators located outside units in a shopping mall or visual indicators used to reduce the search distance (as defined in BS 5839-1));
2) situations in which the fire strategy for the building does not necessitate the provision of VADs as the primary means of giving a warning of fire to any persons;
3) visual indicators used to indicate system or device status, e.g. on CIE or detectors.
DEFINITIONS AND ABBREVIATIONS
For the purposes of this document, the terms and definitions given in BS 5839-1 and BS EN 54-23 and the following apply.
ambient light level
the light level normally present in an area of a building
NOTE In this Code of Practice, in designing a VAD installation, account is taken of the ambient light level, which is likely to vary (e.g. over the course of a day).
CIE control and indicating equipment combined VAD
a VAD combined with another device of a fire detection and fire alarm system EXAMPLE: Combined VAD and alarm sounder or VAD and smoke detector. deaf person
a person who cannot hear sounds less than 80 dBA hard of hearing person
NEED FOR VISUAL ALARM DEVICES
The need for VADs in any specific building will normally be determined by the authority responsible for enforcing fire safety legislation in that building and/or by a fire risk assessment carried out by the person on whom legislation imposes a duty to do so.
EXCHANGE OF INFORMATION AND DEFINITION OF RESPONSIBILITIES
VADs are used to supplement, in specific circumstances, other alarm devices. As such, in providing an effective means of alerting and evacuating occupants of the building, they form part of its fire safety strategy. Therefore, it is particularly important that the use of VADs is based on an agreed building evacuation plan.
In order to ensure that adequate provision is made for the use of VADs, it is advisable that, where relevant, there be consultation between the user or purchaser and the system designer. In some cases, there will also be a need for consultation between the user or purchaser, the system designer and the enforcing authority.
DESIGN CONSIDERATIONS
CONFORMANCE TO EN STANDARDS
VADs should conform to the requirements of BS EN 54-23. Radio linked devices should also conform to the requirements of BS EN 54-25. Devices which incorporate isolators should conform to BS EN 54-17.
COMBINED VADs
Combined VADs should conform to the relevant BS EN standard for each element of the device. Combined VADs can comprise a number of additional and different functions, such as an alarm CIE
POWER SUPPLY
Power supply equipment should conform to BS EN 54-4.
VISUAL ALARM DEVICES IN EXPLOSIVE GAS OR DUST ATMOSPHERES
If it is necessary to install a VAD in areas where an explosive atmosphere could result from the presence of flammable gases, vapours or mists, or the presence of combustible dusts, special protection measures are essential to ensure that the potential for ignition of the atmosphere by the VAD or the wiring to the VAD is minimized.
EXPLOSIVE GAS ATMOSPHERES
Intrinsically safe circuits of VADs should conform to BS EN 60079-25.
EXPLOSIVE DUST ATMOSPHERES
Any systems (or part of a system) protecting an area, or with cables passing through an area, in which there may be an explosive dust atmosphere should conform to BS EN 61241-14 with regard to selection and installation of equipment and BS EN 61241-17 with regard to inspection and maintenance.
MONITORING, INTEGRITY AND RELIABILITY OF VAD CIRCUITS TO CONTROL EQUIPMENT
Visual alarm circuits are external to control equipment. The VADs are generally used in addition or as an alternative to sounders to indicate the need for evacuation of the building.
FAULT MONITORING
a) A fault indication should be given at the CIE within 100 s of the occurrence of any of the following conditions:
SYSTEM INTEGRITY
a) A fault on one circuit containing VADs, should not affect any other circuit;
b) Any fault forming a cross-connection between a visual alarm circuit and another circuit should not affect any circuits other than the two circuits involved;
c) It is recommended that in the event of a single open circuit or short circuit fault on any circuit that serves a VAD, at least one single fire alarm sounder normally located in the vicinity of the CIE should still sound in the event of a fire alarm condition (see BS 5839-1). Where deaf or hard of hearing persons may be required to respond to this alarm condition the alarm sounder in this instance should be supplemented by a VAD;
ALARM ZONES
In many buildings, the evacuation strategy will be very simple; on operation of any manual call point, or detection of fire by an automatic fire detector, fire alarm devices will operate throughout the building to indicate the need for evacuation of the entire building.
OVERLAP SIGNALS
The extent of any overlap of signals from VADs between alarm zones should not be sufficient to result in confusion of occupants in any area of the building.
COMMON VISUAL SIGNAL
A common visual signal should be used throughout all alarm zones to convey the need for evacuation.
VISUAL ALARM SIGNALS
COLOUR AND FLASH RATE
The VAD should emit a white or red light flash as required in BS EN 54-23. In addition, for the first stage of a multi-stage alarm system, the colour amber may be used (see Clause 4.5.4).
Generally, white flashing light is more effective in alerting individuals as it includes a broader spectrum of colours.
FIRE ALARM WARNINGS FOR DEAF AND HARD OF HEARING PEOPLE
Deaf and hard of hearing people can be present in all parts of a building; it is important therefore that all areas are considered when planning for the provision of VADs. The most important areas for the provision of VADs are those where it is possible for a person to be alone or isolated from others with normal hearing. In public areas, deaf and hard of hearing people are likely to receive assistance from the other people present. However, in all areas, the provision of VADs should be adequate for the needs of deaf and hard of hearing people.
FIRE ALARM WARNINGS IN AREAS OF HIGH AMBIENT NOISE
Where high ambient noise might be present for periods of time, it might not be practicable for fire alarm sounders to achieve sound levels greater than the 5 dB above ambient noise level recommended by BS 5839-1 to ensure audibility.
STAGED ALARMS
In simple buildings of limited size, a single-stage fire alarm arrangement is normally used. In this arrangement, fire alarm sounders are either in the on or off state, while VADs are either flashing or off. On operation of any manual call point or automatic fire detector, the fire alarm sounders and VADs operate to provide a single, common evacuation signal throughout the premises immediately (i.e. there is a ‘single-phase’ evacuation).
In certain large and/or high rise buildings, a staged fire alarm arrangement is commonly used. In this arrangement, the initial warning of fire is given in a restricted area or is restricted to key personnel, but can be extended in further stages to warn, ultimately, all occupants of the premises. The arrangement might apply regardless of whether the alarm is triggered by a manual call point or an automatic fire detector, or it might apply only to alarm signals triggered by automatic fire detectors. It is essential to ensure that the arrangement adopted for VADs exactly parallels the arrangement adopted in respect of fire alarm sounders, so that the appropriate signal (e.g. alert or evacuate) can be given by either form of warning device..
PHOTOSENSITIVE EPILEPSY
People with photosensitive epilepsy suffer seizures which are triggered by certain frequencies of flashing lights or contrasting light and dark patterns. Seizures are most likely to be triggered by frequencies between 3 Hz and 30 Hz, although this varies from person to person; while some people are sensitive at frequencies higher than 30 Hz, it is unlikely that seizures will be triggered by frequencies less than 3 Hz.
ON, SPACING AND SITING OF VADS
When designing systems incorporating VADs, a number of factors determining their effectiveness in giving warning should be considered. At the onset of the design, it is important to identify the following:
VAD ILLUMINATION CHARACTERISTICS
BS EN 54-23 specifies VADs in terms of the range at which a required illumination of 0.4 lux is achieved. This defines the coverage volume of VADs compliant with the European standard.
NOTE 1: Reference may be made to Annex A in BS EN 54-23 for method of
measurement of the effective light intensity and the calculation of coverage distance.
BS EN 54-23 defines three categories of VADs for which the coverage volume is defined as follows:
AMBIENT LIGHT LEVEL
The ambient light level in the vicinity of a VAD will affect its visibility and, hence, its ability to give effective warning. In designing the installation, consideration should be given to the variation of the ambient light level during the periods when the VADs are intended to be effective in giving a warning of fire.
The ambient light level is determined by the extent of artificial lighting in combination with any natural lighting. A wide range of lighting levels can be found in applications where VADs are required to be used. Artificial lighting conditions vary to suit the needs of specific human activities e.g. different lighting conditions will be found in dwellings, offices, shops and places of public entertainment. The ambient light level can also be influenced by external natural light conditions such as bright sunshine, daylight, overcast sky, twilight and moonlight.
Information on the recommended illumination in workplaces and typical ambient light levels is given in Annex B.
Because of the large variations in ambient light levels which may exists in specific applications, it is important that the highest level expected should be considered when selecting VADs.
In general, the coverage volume of VADs may be increased in low ambient light levels but may need to be decreased for brightly lit spaces or in spaces that can be flooded by strong daylight, such as rooms with south-facing windows.
REFLECTIVE SURFACES
Some surfaces may reflect or absorb light. It is important to assess and understand the types of surfaces involved as different materials will react differently to the emitted light. The reflection of light may be specular when the entire incident light is reflected in one direction from a shining surface, e.g. glass mirror, polished metal or gloss paint, or it may be diffuse when the light is reflected in a many directions from an uneven or granular surface.
THE EFFECT OF TINTED EYE PROTECTION
In some industrial environments, personnel use tinted eye protection. It should be ensured that the light output of the VADs is bright enough to overcome the attenuation provided by the eye protection. If tints are used, they will attenuate specific colours. In such circumstances, it is preferred that visual alarms should provide white light for maximum effectiveness.
FIELD OF VIEW
BS EN 54-23 requires the manufacturer to declare the coverage volume (volume where the required intensity is achieved) of the VAD. Consideration should be given, however, to the presence of any obstructions, such as partitions or furniture that could affect the actual VAD coverage.
THE ENVIRONMENT
This Code of Practice specifies VADs for two types of application environment, Type A, generally for indoor use and Type B, generally for outdoor use.
SELECTION, SITING AND SPACINGS 4.6.9.1 GENERAL
This clause gives general recommendations for the selection, siting and spacing of VADs. One or several VAD(s) of adequate output can be expected to serve any room or length of corridor if optimally located on perimeter walls or suspended below the ceiling so that the signal can spread throughout the
GENERAL RULES FOR SELECTION AND SITING OF VADS
a) Wall-mounted VADs are likely to be effective in a wide range of applications, including those with high ambient light levels.
b) Ceiling-mounted VADs (or VADs suspended from the ceiling) can be used as an alternative to wall mounted devices and are more practical to install in large open areas or where wall mounting is difficult.
c) The coverage volume of open category devices is specified by the manufacturer, the recommendations of which should be taken into consideration when determining the siting and spacing of the devices at given ambient light levels.
BS EN 54-23 COVERAGE DISTANCE MULTIPLICATION FACTORS
The effectiveness of VADs in a particular application will depend on the level of ambient light (see Clause 4.6.4). Low ambient light permits a reduction in the illumination given by a VAD while maintaining its effectiveness. Conversely, high ambient light will necessitate an increase in VAD illumination in order to achieve the desired effectiveness in warning occupants.
Similarly, it has been identified by investigative tests that the effectiveness of VADs is linked to whether all occupants of a room have, at all times, a clear line of sight of the device (see Clauses 4.6.9.2d and e). In such a case, a reduction in the VAD illumination is possible compared with situation where indirect illumination would otherwise be needed.
USING VADS IN SPACES WITH HIGH AMBIENT LIGHT
a) Where ambient light levels may, at any time, exceed 600 lux, direct viewing is preferred;
b) In situations where lighting level greater than 800 lux is required, for example where highly demanding work such as minute assembly work is carried out, the selection and siting of VADs should be based on photometric calculations. Persons with specialist knowledge should be involved.
POWER SUPPLIES
VADs, when operating, can place greater demands on power supplies than audible alarms. VADs, especially those based on xenon flash tube technology, may consume large amounts of power at start-up and then after each flash. These power demands, although short in duration, can affect operation of the power supply by exceeding its rated capacity and causing protective measures to operate. This can result in the VAD(s) failing to operate correctly, failing to flash or flashing irregularly, or for there to be a reduction of the power supplied to other parts of the system, causing a malfunction.
CABLES, WIRING AND OTHER INTERCONNECTIONS
VADs form part of the primary means for giving warning of fire in particular circumstances, or for particular groups of people. It is, therefore, essential that circuits on which they are connected operate correctly at the time of a fire. It is not normally possible to predict, with any accuracy, those areas of a building in which fire can or cannot occur. At the design stage, the exact routes that cables of VADs will follow may also be unknown.
RADIO-LINKED SYSTEMS
Where VADs are linked to CIE by radio communication, rather than wiring, there is a need for two-way communication between the VAD and the CIE; a radio signal from the CIE will trigger the operation of the VADs, while the VADs must be capable of transmitting a signal to the CIE for monitoring purposes.
Some of the recommendations of this Loss Prevention Code of Practice, applicable to wired VADs, are
Such a facility should not impair the VADs’ ability to provide an adequate visual warning to the occupants of the building in the event of fire.
ELECTROMAGNETIC COMPATIBILITY
The installation of the VADs should comply with the recommendations of Clause 28 of BS 5839-1.
Particular attention should be given to the following:
• the susceptibility of the VAD to electromagnetic interference;
• the level of screening afforded by the cable;
• the separation distance between the fire alarm cables and the cables of other services.
Specific recommendations for EMC compliance given by the manufacturer of the VAD should be followed.
ELECTRICAL SAFETY
As VADs are part of the fire alarm system, the recommendations of BS 7671 regarding safety and earthing are applicable to circuits serving VADs.
LV and ELV circuits should be segregated in accordance with Clauses 26.2n) and 28 of BS 5839-1. If any ELV fire alarm cables share the same wiring containment with other cables, then the cable insulation of the fire cables should be rated for the highest voltage.
Should the VAD be removable (e.g. from a base) and removal would expose, to touch, conductive parts at ELV potential, then, in wet conditions, such as swimming pools, saunas, abattoirs etc, one or more of the following should apply:
RESPONSIBILITY OF INSTALLER
a) The installer should ensure that there is consultation with all relevant interested parties that may include:
• the user or purchaser;
• the designer;
• the supplier of the VADs;
• consultants that include the architects, mechanical, lighting and electrical consultants or fire engineering consultants.
b) The installer should report and document any variations not clearly identified in the documented design (other than errors or ‘snags’ for which rectification is proposed) – these variations may relate to circumstances that may have been unknown to the designer e.g. change of structure of the building that will affect the effectiveness of the particular VADs being installed.
INSTALLATION PRACTICES AND WORKMANSHIP
a) The installation of the VADs should comply with the recommendations of sub¬clauses 37.1 and 37.2 of BS 5839-1.
b) The recommendations of the VAD manufacturer on the correct mounting height and orientation of VADs should be followed to ensure correct light dispersal and coverage is achieved to meet minimum light levels detailed in Clause 4.6)
INSPECTION AND TESTING OR WIRING
Wiring should be inspected and tested in accordance with the recommendations of sub- clauses 38.1 and 38.2 of BS 5839-1.
COMMISSIONING PROCEDURES
Commissioning of VADs should be carried out in accordance with the recommendations of Clause 5 of BS 5839-1. In addition, it should be confirmed that:
a) the positioning and rating of VADs complies with Clause 4.6.9 and the system
designer’s installation drawings;
In addition to the recommendations of Clause 40 of BS 5839-1, the documentation should also include “as fitted” drawings showing the location and light output ratings of all VADs in accordance with the formats specified in Clause 4.3.6.2 of BS EN 54-23.
CERTIFICATION, ACCEPTANCE AND VERIFICATION
The certification, acceptance and verification processes recommended by BS 5839-1 apply.
ROUTINE TESTING
BS 5839-1 recommends that fire detection and fire alarm systems be tested every week. The main purpose of the weekly test is simply to ensure that there has not been a major failure of the entire system or a significant part of the system i.e. that the control equipment is capable of processing a fire alarm signal and providing an output to fire alarm devices (including VADs). Accordingly, it is not necessary to confirm that all circuits serving VADs operate correctly at the time of this test.
INSPECTION AND SERVICING
Inspection and servicing of equipment and circuits serving VADs, and the VADs themselves, should comply with the recommendations of Clause 45 of BS 5839-1. In particular, at the time of periodic inspection and test, the correct operation of all circuits serving VADs should be confirmed.
Every year, the operation and, where applicable the synchronization, of each VAD should be checked, and, where necessary, the VAD lens should be cleaned to remove any dirt or deposits that would significantly decrease light output. It should also be confirmed that VADs are not obstructed from view.
Note: The annual work described above may be carried out over the course of two or more service visits during each 12-month period.