In terms of design and installation, there are a number of key changes. Notably, L4 systems are now required to include fire detection at the top of lift shafts, while L2 systems must now consider areas where people sleep—not just rooms identified through general risk assessments. Lockdown alarms can now be incorporated into fire alarm systems, but the tone used must be clearly different from the standard fire alarm sound. The guidance around ceiling obstructions, such as ductwork or beams, has been clarified to ensure detector coverage is not compromised. For Category L systems, fire signals must now be monitored within 90 seconds, with faults detected within 3 minutes. The method for calculating standby battery capacity has been revised to improve clarity, and the requirement for mains cables to be red has been re-emphasised.

Some practices that were previously treated as permissible variations are no longer allowed. For example, remote monitoring in care homes and inaccurate or absent zone charts can no longer be brushed aside as site-specific deviations. In addition, low-risk lobbies, such as toilet lobbies, may now require detection depending on the system type. A new label is also required on alarm panels that are connected to the fire and rescue service, stating: “FALSE ALARM NOTICE: This fire alarm has an active connection to the fire and rescue service.”

Changes have also been introduced around ongoing maintenance and servicing. All variations from the standard must now be logged in the site’s fire alarm logbook, and any competent person carrying out maintenance must engage in continuous professional development (CPD). Engineers are now permitted to mark the battery installation date directly on the battery, and while servicing is still required every six months, there is now flexibility—allowing for visits between five and seven months without falling foul of the standard. Every service must include a check of the control panel’s clock, and engineers must verify that zone charts are current and correct. Importantly, any redundant devices or interfaces that are no longer in use must be removed, and all interfaces must remain accessible—concealed or blocked interfaces are now deemed non-compliant.

On the documentation and certification front, all model certificates referenced in the standard have been updated to reflect paragraph renumbering, even if the actual wording of the clauses remains unchanged. A brand new Section 7 has been added, covering extensions and modifications to systems, helping engineers and designers manage changes to existing installations more clearly and consistently. Clause 4 has been moved into the introduction, and Clause 33 has been merged with Clause 31 to consolidate the recommendations on managing false alarms. The standard has also updated its terminology—for example, “care homes” are now referred to as “residential care premises,” and “fire service” has become the “fire and rescue service.”

These changes are more than just cosmetic or administrative—they reflect lessons learned from real incidents, aim to reduce confusion in emergencies, and seek to raise the overall standard of fire safety in non-domestic buildings. For organisations that rely on compliant, well-maintained fire alarm systems, these updates are a timely reminder to review current practices, retrain staff where necessary, and ensure documentation is brought in line with the 2025 edition.

If you’re unsure about how these changes affect your property or your responsibilities, speak to Sanjay on 01748 811992. The updated BS 5839-1:2025 isn’t just a new version of the old—it’s a signal that fire safety is evolving, and so must we.