Visual warning devices on fire detection and alarm systems are becoming more and more frequent, so C-Tec’s marketing manager Andy Green informs us where, why and when such devices should be implemented.
Beacons, strobes, ‘VIDs’ and ‘VADs’ – what on earth is the difference? Beacons and strobes have been used in fire alarm systems to warn the hearing impaired of a potential fire for many years. However, four years ago the code of practice for the design and installation of fire systems (BS 5839 part 1, published in 2013) introduced a new type of device – an EN54 part 23 certified ‘VAD’ or, to give it its full title, a Visual Alarm Device.
So what is a Visual Alarm Device (VAD)?
A VAD is a warning device intended for use on a fire alarm system that has been independently certified as meeting the requirements of the EN 54 part 23 product standard. This standard was introduced to ensure such devices are fit for purpose.
Prior to its introduction, there was no industry standard that specified the durability, light output, performance criteria or installation requirements of a visual warning device. Di erent manufacturers therefore rated their beacons and strobes in di erent ways – usually by their power consumption rather than by their light output. This increased the risk of inappropriate devices being used and potentially jeopardised the lives of the people they were intended to protect – the hearing impaired or people wearing ear defenders.
The concept of VADs was great in theory but when BS 5839 part 1 2013 was introduced, very few certified VADs existed. In the absence of such devices, many installers continued to use the same uncertified beacons and strobes they always had. These uncertified devices became known as VIDs (Visual Indicating Devices) to di erentiate them from VADs and many felt it was acceptable to continue using them moving forwards. Clearly it was not!
In order to address the issue, The Fire Industry Association (FIA) has recently published a document entitled: “Guidance on the application of primary visual alarm devices (VADs) and supplementary visual indication devices (VIDs)”.
Put simply, this guidance makes it clear that where a visual indicator is used as a primary alarm, it must be a VAD certified to EN 54-23 unless the building’s risk assessment SPECIFICALLY states that it does not need to be.
So where should VADs be used?
The FIA’s guidance states to comply with the Equality Act, Building Regulations and the recommendations of codes of practice such as BS 5839-1 and BS 8300, EN 54-23 certified VADs must be installed in all sanitary accommodation (not just accessible WCs), all hotel bedrooms, student accommodation and similar properties, plus anywhere where people with impaired hearing are likely to be alone, such as isolated offices.
It goes on to say uncertified VIDs must NOT be used to warn building occupants of a fire condition. They can, however, be used as supplementary indicators, for example, as remote indicators for a hidden fire detector.
It’s important to note there are instances where a risk assessment may call for alternative methods of alerting the hearing impaired, such as vibrating pillow devices, pagers or ‘buddy’ systems, all of which rely on some form of management process. However, the FIA guidance is clear: if a risk assessment doesn’t specifically state otherwise, VADs should be used in all mandated situations.
EN54-23 specifies the requirements, test methods and performance criteria for visual alarm devices (VADs) used in fire alarm systems. It defines a VAD as a light that flashes at 30-120 times a minute.
To comply with the standard, a VAD must generate a minimum illumination level of 0.4 lux in specific test conditions. These tests are conducted in a complex manner that requires the VAD to emit light at several hundred lumens. On completion of the tests, the VAD is given a ‘W’ (wall-mounted), ‘C’ (Ceiling mounted) or ‘O’ (Open) class rating.
This rating can then be used to determine the VAD’s actual coverage in real-life situations, depending on ambient light, mounting position and viewing angle.
The following guide shows you how to calculate VAD coverage in six easy steps using two of C-TEC’s EN54-23 certified VADs as examples (please note that C-TEC’s VADs are fully compatible with its XFP and ZFP range of XP95/Discovery addressable fire panels):
STEP 1: EDUCATE YOURSELF ON THE RATED COVERAGE OF C-TEC’S C-3-8 BASE VAD
Certified as a C-3-8 device where: C = ceiling; 3 = up to 3m height and 8 = up to 8m diameter. Light output is cylindrical so width must be divided by 1.414 to determine square area coverage (i.e. 8m/1.414 = 5.65m).
STEP 2: EDUCATE YOURSELF ON THE RATED COVERAGE OF C-TEC’S W-2.4-8.2 HI-OUTPUT WALL VAD
Certified as W-2.4-8.2 devices where: W = wall, 2.4 = 2.4m height and 8.2 = 8.2m width. Light output is cuboid so no additional width calculation is required.
STEP 3: DETERMINE THE AMBIENT LIGHT LEVEL
Ambient light can significantly increase or decrease a VAD’s coverage. Use a BS667 compliant lux meter in the area to be covered or refer to the architect’s drawings.
STEP 4: DECIDE WHETHER THE VIEWING ANGLE IS DIRECT OR INDIRECT
Consider how the room will be occupied and used. Direct viewing (line of sight) is preferable but not always possible. For example, in a room where someone is looking down at a workstation or desk, the required viewing angle is likely to be indirect.
STEP 5: APPLY MULTIPLICATION FACTORS BASED ON AMBIENT LIGHT, VIEWING ANGLE AND MOUNTING POSITION
Example: if ambient light is 250 lux and the viewing angle is direct, the coverage of a C-3-8 ceiling VAD can be multiplied by 1.9, increasing its cylindrical coverage from 8m to 15.2m (or 10.7m square).
STEP 6: POSITION THE REQUIRED NUMBER OF VADS IN THE AREA REQUIRING COVERAGE
For more information about C-TEC’s range of VADs visit: www.c-tec.com.
