Visual Alarm Devices and BS EN 54-23
A fire alarm that can only be heard leaves out anyone who cannot hear it, and struggles in places too noisy for a sounder to cut through. Visual alarm devices — the flashing beacons that warn by sight — fill that gap, but only if their light actually reaches the people who need to see it. That is where coverage, and the product standard BS EN 54-23 that underpins how coverage is defined, come in. This guide covers what VADs are, why coverage matters, and what to check.
The central point is that a visual alarm device only warns effectively if its rated coverage suits the space, which is why BS EN 54-23 and correct coverage selection matter.
Who this is for
This is for competent fire alarm engineers selecting, siting or maintaining visual alarm devices. The experience level assumed is competent engineer. Use it for the principles; whether and where VADs are needed comes from the fire risk assessment and the design, and their coverage and siting follow BS 5839-1 and the manufacturer's data against BS EN 54-23. The aim is visual warning that actually reaches the people who rely on it.
What VADs and BS EN 54-23 are
A visual alarm device provides a visual warning of fire — typically a flashing light — to alert people where an audible alarm alone may not be enough, such as noisy areas or for people who cannot hear the sounder. BS EN 54-23 is the product standard for fire alarm visual alarm devices, addressing how their coverage is defined and specified so that a VAD's effective reach is a known, comparable quantity rather than a guess. VADs are used where the fire risk assessment and design call for visual warning. Coverage and selection follow BS 5839-1 and the manufacturer's data against BS EN 54-23. Understanding that a VAD has a defined, rated coverage is the foundation for using it properly.
Why coverage matters
Coverage is where VADs succeed or fail in practice. A visual alarm device only works if its signal actually reaches the people who need to see it, so the device's rated coverage — the volume or area it can effectively illuminate to the required level — must suit the space it is installed in. Under-specifying coverage leaves parts of a room where the visual warning simply is not effective, which defeats the purpose for anyone in those areas. BS EN 54-23 provides the basis for defining a VAD's coverage in a comparable way; how VADs are then selected and sited for a space comes from BS 5839-1 and the manufacturer's data, applied to the actual room and its layout. Matching rated coverage to the space is the essential discipline.
When VADs are used
VADs are not fitted everywhere by default; they are used where a visual warning is needed in addition to, or in support of, audible warning. Typical cases include noisy environments where sounders alone may not be relied upon, and places where people who cannot hear the alarm need to be alerted by sight. Whether and where VADs are needed comes from the fire risk assessment and the design, not a blanket rule, and it connects closely to accessibility — ensuring the warning reaches everyone. Their coverage and siting follow BS 5839-1 and the manufacturer's data against BS EN 54-23, applied to the environment and the people using it. The right question is who needs to see a warning here, and does the VAD reach them.
Checking VADs on service
On service, VADs need checking for coverage as well as function. Confirm the devices operate, that their coverage suits the spaces and the people using them, that they are not obstructed by furniture, fittings or partitions, and that changes to layout or use have not left visual warning gaps. From field experience, VADs with coverage that does not suit the space, and devices obstructed or added later without coverage in mind, are the recurring findings. Record what you find, and flag any area where the visual warning is not effective for those who rely on it, so it can be reviewed rather than leaving someone unwarned.
Common points to check
Recurring issues include VAD coverage not suited to the space, devices obstructed, and layout or use changes leaving visual warning gaps. Confirming visual warning is effective for everyone who relies on it is the essential check.
When not to rely on this alone
When not to use this article: do not use it to specify VAD coverage for a specific building. That comes from the fire risk assessment, BS 5839-1 and the manufacturer's data against BS EN 54-23, applied by competent professionals.
Relevant standards
Visual alarm devices are addressed by the product standard BS EN 54-23, with selection and siting within BS 5839-1, a code of practice, applied with the manufacturer's data. The legal duty for fire precautions in most non-domestic premises sits under the Regulatory Reform (Fire Safety) Order 2005. Separate the legal duty from the recommended methods, and always work to current editions and current manufacturer data.
Professional disclaimer
This is an educational and workflow resource for competent engineers and does not replace the current British Standards, the manufacturer's data, the fire risk assessment, or competent judgement. Verify VAD coverage and selection against current documentation for the actual space.
Related documentation
Use this with BS EN 54-23, the current BS 5839-1 and the manufacturer's VAD data. Record VAD coverage against the spaces, and flag any area where visual warning is not effective for those who rely on it.