BS 5839 is a British Standard that outlines the recommended practices for designing, installing, commissioning, and maintaining fire detection and fire alarm systems in buildings. It provides a framework to ensure systems are appropriate for their environment, reliable in operation, and effective in alerting occupants to a fire.

BS 5839 is divided into two key parts, each focused on different types of premises:

• BS 5839-1: Covers non-domestic (commercial, public, and industrial) buildings.

• BS 5839-6: Applies to domestic premises, such as houses, flats, and shared housing.

Each part provides guidance specific to the needs and risks associated with the building type.

Following BS 5839 helps ensure fire alarm systems are correctly specified and installed, giving early warning of a fire and supporting a safe evacuation. It also helps responsible persons meet their legal duties under UK fire safety regulations, such as the Regulatory Reform (Fire Safety) Order 2005.

BS 5839 introduces different system categories to define the level of protection:

• Category L systems (e.g., L1 to L5) – life protection in non-domestic buildings.

• Category P systems (e.g., P1 and P2) – property protection in non-domestic buildings.

• Grades A to F – used in domestic premises under BS 5839-6, ranging from complex addressable systems (Grade A) to basic battery-operated detectors (Grade F).

These categories help designers choose the appropriate system based on the building’s risk and usage.

BS 5839 is aimed at several key groups:

• Fire alarm system designers and installers

• Building owners and landlords

• Responsible persons under fire legislation

• Facilities and maintenance managers

Each of these stakeholders plays a role in ensuring the fire alarm system remains compliant and functional over time.

The standard offers guidance on:

• Detector and call point placement

• Wiring and power supply requirements

• Control and indicating equipment

• Commissioning and handover procedures

• Regular system testing and maintenance

By following these recommendations, building operators can reduce false alarms and improve response times during emergencies.

Compliance doesn’t end after installation. BS 5839 places importance on regular inspection and maintenance to ensure the system remains effective. Routine servicing is usually carried out twice a year, depending on the premises and system type.

If you need support with designing, installing, or maintaining a fire alarm system in line with BS 5839, our team at Cobra Fire and Security is here to help. We offer expert advice and fully compliant services to keep your building safe and up to standard.