# BS 5839 and Its Application to Fire Alarm Systems ## Understanding BS 5839 **BS 5839** is the British Standard that sets out best practice recommendations for the **design, installation, commissioning, and maintenance of fire detection and alarm systems**. It plays a vital role in achieving compliance with UK fire safety legislation, particularly in non-domestic buildings such as offices, schools, healthcare facilities, and commercial premises. BS 5839 is split into two major parts: * **BS 5839-1** → Applies to fire detection and alarm systems in **non-domestic premises**. * **BS 5839-6** → Covers systems used in **domestic (residential) premises**. This page focuses on the updated **BS 5839-1:2025** edition, which replaces the 2017 version. --- ## Why BS 5839-1:2025 is Essential for Fire Alarm Systems Compliance with **BS 5839-1:2025** helps to: * Improve **life safety** by enabling early warning and effective evacuation. * Reduce **property damage** through prompt detection and fire brigade response. * Satisfy **legal obligations** under fire safety laws like the **Regulatory Reform (Fire Safety) Order 2005**. * Provide a structured approach to **system reliability**, false alarm reduction, and robust documentation. While it is not a legal document in itself, BS 5839-1 is widely used to demonstrate compliance with statutory fire safety duties. --- ## Key Changes Introduced in the 2025 Edition ### **Clause Restructuring and New Section** * **Clause 4** has been moved into the **Introduction**. * **Clause 33** on false alarms is now integrated with Clause 31. * A new **Section 7** has been added, covering **extensions and modifications** to existing systems. ### **Stricter Variation Controls** * Certain departures from recommendations are now clearly stated as **unacceptable** in Clause 6. For example, omitting a zone plan in multi-zone buildings is not permitted. ### **Improved Manual Call Point Guidance** * Siting rules have been simplified. Manual call points must be no more than **45m travel distance**, or **30m if the layout is uncertain**. ### **Detector Use in Sleeping Accommodation** * The standard now advises against using heat detectors in sleeping rooms, recommending faster-reacting alternatives instead. ### **Cybersecurity Considerations** * Clause 43.4 includes requirements for **cybersecurity and remote services**, acknowledging modern system vulnerabilities. --- ## Key Elements of BS 5839-1:2025 for Fire Alarm Systems ### **System Categories and Purpose** * **Category M** → Manual systems without automatic detection. * **Category L** → Life protection (L1 to L5, based on risk). * **Category P** → Property protection (P1 or P2). Each category outlines specific detection coverage and design principles. ### **System Design Considerations** * **Risk-Based Design** → System layout must be informed by a fire risk assessment. * **Detector Selection** → Match detector types to environmental risks (e.g. avoid heat in sleeping areas). * **Alarm Performance** → Sound pressure levels must be sufficient for clear occupant warning. * **False Alarm Strategy** → Use appropriate siting, configuration, and detection technologies to reduce nuisance activations. ### **Installation Requirements** * **Cabling** → Must be fire-resistant and installed using appropriate support systems. * **Power Supply** → Both mains and compliant standby battery supply must be verified. * **Call Point and Detector Positioning** → Follow updated distance limits and placement rules. ### **Inspection and Maintenance** * **Weekly Testing** → Test a manual call point each week. * **Monthly Checks** → Inspect batteries and verify charging systems. * **Annual Servicing** → Comprehensive testing of all components. * **Logbook Maintenance** → Record tests, faults, false alarms, and maintenance actions. --- ## Consequences of Non-Compliance Failure to comply with BS 5839-1:2025 can result in: * **Increased safety risk** due to ineffective alarm coverage. * **Legal action** under fire safety legislation. * **Frequent false alarms**, risking fines or loss of confidence in system performance. * **Insurance issues**, including potential refusal of claims after a fire. --- ## Final Thoughts **BS 5839-1:2025** reflects modern best practices and addresses lessons learned from fire incidents. Compliance supports: ✅ Safer buildings and occupants. ✅ Fewer false alarms. ✅ Legal and insurance alignment. Whether you're designing, installing, or maintaining a fire alarm system, applying the updated BS 5839-1 is essential to uphold safety, legal duties, and system performance.