BS 5839-1 (often written BS5839-1) is the British Standard that sets out recommendations for the design, installation, commissioning and maintenance of fire alarm systems in non-domestic premises. A new edition, BS 5839-1:2025, was published on 30 April 2025 and replaces the 2017 version. If you run a shop, hotel, restaurant, warehouse or other business premises in Kent, London or East Sussex, it helps to know what has changed and, just as importantly, what has not.
This guide explains the main changes in plain English, what they mean for an existing fire alarm, and what to ask your fire alarm company. It draws on BSI's announcement of the standard and on guidance from the Fire Industry Association (FIA) and NSI. The sources are listed at the end.
In this guide
The short version
BS 5839-1:2025 was published on 30 April 2025 and replaces the 2017 edition.
It is a code of practice, not legislation. The legal duties sit in the Regulatory Reform (Fire Safety) Order 2005.
For rooms where people sleep, it recommends automatic detection other than heat detectors. The FIA and NSI both say this is not retrospective.
It recommends servicing at intervals of approximately six months, and now accepts one visit between five and seven months after the previous one.
It adds a false alarm notice for monitored systems, sets signalling times, and tightens the rules on zone plans and recorded variations.
New work in extensions and alterations should follow the 2025 edition.
What is BS 5839-1:2025, and is it the law?
The full title is Fire detection and fire alarm systems for buildings, Part 1: Design, installation, commissioning, and maintenance of systems in non-domestic premises, Code of practice. BSI, the UK national standards body, published the 2025 edition on 30 April 2025. It is a revision of the 2017 edition, which it replaces, and it is referenced in both volumes of Approved Document B, the building regulations guidance on fire safety.
It covers systems made up of manual call points, sounders, automatic fire detectors and control panels, in buildings used for commercial, public or industrial purposes such as shops, hotels and restaurants. Fire alarms in homes are covered by a different part of the standard, BS 5839-6.
Because it is a code of practice, BS 5839-1 makes recommendations rather than setting out law. In England and Wales, the legal duties come from the Regulatory Reform (Fire Safety)
Order 2005. Under the Order, the responsible person, usually the employer or the person in control of the premises, must make sure the premises have suitable fire detectors and alarms where necessary, and that fire safety equipment is subject to a suitable system of maintenance and kept in working order. BSI describes the standard as intended to support compliance with fire safety legislation. For the wider legal picture, see our guide to fire alarm rules for Kent businesses.
The main changes in BS 5839-1:2025
The standard has been revised throughout, and some changes are technical details for engineers. These are the ones most likely to matter to the people who own, manage or pay for a fire alarm.
Sleeping accommodation: heat detectors are no longer the first choice
For rooms where people sleep, the 2025 edition recommends prioritising automatic fire detection other than heat detectors, such as smoke or multi-sensor detectors, to improve early detection. BSI gives hotels, care homes and student accommodation as examples of where this matters.
The FIA and NSI both say this is not retrospective. Existing systems do not need to be changed for this reason alone, but it is relevant when a system is upgraded, replaced or extended.
Servicing: the six-month interval now has some flexibility
The standard recommends servicing at intervals of approximately six months. The 2025 edition now accepts one visit falling between five and seven months after the previous one. At each visit, the engineer should also check that the panel clock is correct, so that events are logged accurately. At the annual visit, the zone identification shown on the panel should be checked against the zone plan. Our fire alarm maintenance page explains what a service visit includes.
Zone plans and recorded variations
A variation is an agreed departure from the standard's recommendations, such as an unusual detector position. The 2025 edition says all agreed variations should be recorded in the system logbook.
It also lists two variations that are now unacceptable, which BSI says reflects a number of fatal fires. The first is having no zone plan, the diagram showing which part of the building each zone covers, where a storey has more than one zone, particularly where people sleep. The second is having no facility to send fire alarm signals to an alarm receiving centre in a residential care home, or in supported housing where the standard calls for it.
A false alarm notice on monitored systems
If your fire alarm is connected to the fire and rescue service through an alarm receiving centre, the 2025 edition recommends a notice on or next to the control panel. It reminds the people running the premises that the system is connected, so that tests can be notified in advance and avoid false alarms.
The standard also recommends that every false alarm is investigated, and that whoever hands the system over explains this to the user.
Faster signalling and the PSTN switch-off
For systems that send fire alarm signals to an alarm receiving centre, the 2025 edition sets maximum transmission times. On Category L (life protection) systems, a fire signal should reach the alarm receiving centre within 90 seconds. On Category P (property protection) systems, it should reach the centre within 120 seconds. On Category L systems, a total failure of the signalling equipment should be reported within three minutes.
The FIA links these timings to the PSTN switch-off and the move to all-IP networks. If your alarm still signals over a phone line, our PSTN switch-off page has a quick check, and our guide to 4G, IP and dual-path alarm communicators explains the replacement options.
Remote access and cyber security
Many fire alarm panels can now be serviced remotely. The 2025 edition recommends preventing unauthorised access to the system and its network connections, for example by locking the communications cabinet. It also recommends authenticating any request to accept a remote connection, and carrying out a risk assessment before any remote service takes place.
Clearer rules for extensions and alterations
The 2025 edition adds a new section on extensions and modifications. New work in an extension should follow the current edition, even though the rest of the system may not conform to it. When equipment is taken out of use, the standard recommends removing it where practicable, or labelling it clearly as not in use, so that no one assumes an area is still protected. Our fire alarm installation page explains the systems we install.
Competence and documentation
The definition of a competent person now carries a note that maintaining competence is likely to require continuing professional development. The standard also recommends that handover documentation includes a cause and effect description, which explains what the system does when a device is activated. For a simple building that can be a single sentence, such as confirming that the system operates as a simultaneous evacuation. For a complex one it can be a matrix.
Finally, the standard has been restructured and renumbered, so certificates and reports may now refer to different clause numbers from those you are used to.
Does your existing fire alarm need to change?
This is the question most business owners ask, and the guidance gives a measured answer. BSI says the revision updates its recommendations so that new work, including the new-work parts of extensions and alterations, can be carried out consistently. The one change the FIA and NSI have specifically addressed, the move away from heat detectors in sleeping rooms, is not retrospective.
That does not mean you can ignore the standard. The new edition does not change the duties the Fire Safety Order places on the responsible person, and your fire risk assessment should reflect how your premises are used. If your alarm was designed to the 2017 edition or earlier, ask your fire alarm company whether anything in the 2025 edition affects your system. The answer depends on the system, the building and how it is used, so it is a question for an engineer who has seen it.
What Kent businesses should do now
These checks are worth working through with your fire alarm company at your next service visit:
Ask which edition of BS 5839-1 your system was designed and installed to, and whether anything in the 2025 edition affects it.
If your building has more than one zone, check that a zone plan is available and matches the zones shown on the panel.
Look at the system logbook. It should record any agreed variations from the standard.
If your alarm is monitored, check that there is a notice on or next to the panel, and agree a routine for telling the alarm receiving centre before any test.
If your alarm signals over a phone line, ask how it will send signals after the PSTN switchoff, and whether the new route meets the transmission times above.
If you provide sleeping accommodation, ask what type of detectors are fitted in the bedrooms, and plan any change for your next upgrade.
If you are extending or altering your premises, tell your fire alarm company early, because new work should follow the 2025 edition.
Make sure the company working on your system is independently certified. GMSE Fire & Security holds BAFE SP203-1 certification, which covers the design, installation, commissioning and maintenance of fire detection and alarm systems.
GMSE Fire & Security covers Kent, London and East Sussex. If you would like an engineer to look at your fire alarm, book a free site survey.
Frequently asked questions
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BS 5839-1:2025 is a code of practice, so it makes recommendations rather than setting out law. The legal duties come from the Regulatory Reform (Fire Safety) Order 2005, which applies in England and Wales. It requires the responsible person to provide suitable fire detectors and alarms where necessary, and to keep fire safety equipment properly maintained. BSI describes the standard as intended to support compliance with fire safety legislation
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BSI published BS 5839-1:2025 on 30 April 2025. It replaces the 2017 edition, which has been withdrawn.
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No. BS 5839-1 covers non-domestic premises, such as shops, hotels and restaurants. Fire alarms in domestic premises are covered by a different part of the standard, BS 5839-6.
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The 2025 edition recommends prioritising detection other than heat detectors in rooms used for sleeping. The FIA and NSI both say this is not retrospective, so existing systems do not need to be changed for this reason alone unless they are being upgraded, replaced or extended. If you provide sleeping accommodation, ask your fire alarm company what is fitted and whether it suits the building.
Does the 2025 edition change how often a fire alarm should be serviced?
The standard still recommends servicing at intervals of approximately six months. The 2025 edition now accepts one visit falling between five and seven months after the previous one, which gives some flexibility with scheduling.
About this guide. Last checked in October 2026. This is a plain-English summary. It is not a substitute for the standard itself, which is available from BSI, or for advice from a competent fire alarm engineer about your premises. It draws on:
BSI's announcement of the updated standard (30 April 2025) and its guide to the changes
The FIA's guide to the changes in BS 5839-1:2025
NSI's notice on the publication of BS 5839-1:2025 and technical bulletin 0070
The Regulatory Reform (Fire Safety) Order 2005 on legislation.gov.uk, Article 13 and Article 17