BS 5839 Explained
BS 5839 is the British Standard that provides recommendations for the planning, design, installation, commissioning and maintenance of fire detection and fire alarm systems in non-domestic premises.
First published in 1980 and updated regularly since, it ensures fire detection systems are designed to protect both life and property. The standard is split into several parts, with Part 1 (BS 5839-1) focusing specifically on systems in commercial buildings.
The 2025 revision introduces updated guidance in response to technological developments, risk management best practices and lessons learned from real-world incidents. Its primary aim remains the same: to ensure reliable and effective fire detection that helps safeguard occupants and minimise false alarms.
Key Changes in the New BS 5839-1:2025 Standard
The 2025 update supersedes BS 5839‑1:2017 and introduces several key changes, including:
- Lift Shafts & Low-Risk Areas Now Covered
- Detection must now be included in lift shafts and some previously exempt lobbies.
- Linear Heat Detection Recognised
- BS 5839‑1:2025 now references BS EN 54‑22 (analogue LHD) and BS EN 54‑28 (non-resettable LHD), acknowledging linear heat cable systems as compliant detection methods when properly applied.
- Battery Backup & Recording
- New guidance for battery sizing and calculation, with battery condition now to be recorded during servicing.
- Mandatory Red Fire Alarm Mains Cables
- All fire alarm mains supply cables must now be coloured red for easy identification.
- New Section for Modifications
- Section 7 now covers extensions and modifications, ensuring legacy systems are brought up to standard where possible.
Understanding Component Standards: BS EN 54-22 and BS EN 54-28
BS EN 54-22
BS EN 54‑22 covers analogue or resettable linear heat detection systems. It sets performance and testing requirements for heat-sensitive cables that detect temperature changes along their length, commonly used in tunnels, car parks and industrial sites.
BS EN 54-28
BS EN 54‑28 defines requirements for non-resettable linear heat detectors, which trigger once a specific temperature is reached. They’re ideal for harsh environments where early, reliable heat detection is critical.
BS EN 54-22 and BS EN 54-28 are component standards for linear heat detection systems. The key difference lies in reset capability: EN 54-22 covers resettable detectors, while EN 54-28 covers non-resettable types. These classifications are important as they define how detectors behave during and after activation, ensuring the right type is used for the application and that systems meet performance and safety requirements under BS 5839‑1.
Linear Heat Detection Guidelines in the New BS 5839-1:2025
Clause 33.2.2 of BS 5839‑1:2025 formally recognises linear heat detection (LHD) as a suitable method of fire detection in environments where traditional smoke or heat detectors are not practical.
This includes challenging locations such as tunnels, cable trays, car parks and industrial sites. The standard now directly references BS EN 54‑22 for analogue/resettable systems and BS EN 54‑28 for non-resettable types. These component standards ensure that LHD systems meet strict performance and reliability criteria. Including them in BS 5839‑1 affirms their role in compliant fire system design, offering greater flexibility while maintaining life safety and system integrity in difficult-to-monitor areas.
FyreLine Linear Heat Detection (LHD) systems provide a reliable and cost-effective solution for early fire detection in environments where conventional detectors may be unsuitable.
Designed to monitor heat along the entire length of a cable, FyreLine systems respond quickly to abnormal temperature rises, making them ideal for applications such as warehouses, tunnels, power distribution and transportation infrastructure. With both resettable and fixed options available, FyreLine detectors meet the latest BS EN 54‑22 and BS EN 54‑28 standards.
Easy to install and integrate with existing fire alarm systems, FyreLine delivers enhanced protection, accuracy, and compliance for even the most demanding environments.
The FyreLine EN54 Fixed system is a BS EN 54‑28:2016-approved, non-resettable, fixed linear heat detection solution. It monitors heat across two zones up to 1,000m, pinpoints alarm locations and comprises LHD cable, a dual‑zone controller and an end-of-line module.
The FyreLine Resettable LHD system features a heat-sensitive cable, controller and EOL module, providing adaptive pre‑alarm and alarm thresholds to detect overheat conditions accurately. It’s EN 54‑22 approved and UL 521 listed and allows easy system reset after alarm events.
Where to Use Linear Heat Detection
Car Parks
FyreLine Linear Heat Detection provides dependable fire detection in car parks and is unaffected by smoke, fumes or ventilation systems. It offers continuous coverage across large areas, ensuring early warning and enhanced safety.
Cable Trays
FyreLine Linear Heat Detection offers continuous, reliable fire detection along cable trays. Unaffected by smoke, dust or airflow, it ensures early warning of overheating cables in high-risk industrial environments.
Warehouses
FyreLine Linear Heat Detection provides continuous coverage across high‑racking and storage zones, remaining unaffected by dust, airflow or contaminants. Ideal for early fire detection in expansive, automated warehouse settings.
PV Solar
FyreLine Linear Heat Detection offers cost-effective, low-maintenance fire protection tailored for solar PV systems. It withstands UV, dust and weather, detecting overheating anywhere along its length with precise location feedback.
Barns and Stables
FyreLine Linear Heat Detection ensures early fire detection in stables. It is resilient to dust, humidity, airflow and animal movement, offering continuous temperature monitoring and precise alarm location for enhanced safety.
Plant Rooms
FyreLine Linear Heat Detection provides early fire warning in plant rooms, offering reliable performance in high-risk areas with machinery, heat and fumes. It ensures continuous monitoring where traditional detectors may fail.
FyreLine LHD Cables meeting the BS 5839-1:2025 Standard
Why Choose Eurofyre?
- Complete System Supplier
- Eurofyre supplies all aspects of fire detection including linear heat detection and its associated products and can provide expert advice and consultation.
- Demonstration and Training
- We offer demonstrations and expert training on a range of systems, including FyreLine Resettable linear heat detection systems, in our very own sophisticated training facility.
- After-Sales Support
- Eurofyre offers both on-site and telephone support to assist you in ensuring that your system is fully functional and operating at maximum efficiency. Our after-sales care and support are second to none.
For more information about FyreLine EN54 Fixed Linear Heat Detection or FyreLine Resettable Linear Heat Detection, or to discuss any of the other products that Eurofyre has to offer, please feel free to get in touch either by phone on +44 (0) 1329 835 024, by email to sales@eurofyre.co.uk or via the online enquiry form situated on our contact page. Don’t forget you can follow us on LinkedIn, and Instagram or sign up to our newsletter (in the footer below) to receive all the latest information from Eurofyre.