Fire Alarm Systems

Overview of Fire Alarm Systems

Fire alarm systems are essential life safety systems designed to detect and alert occupants of fire or smoke at the earliest possible stage. Their primary purpose is to protect life, property, and business continuity by providing early warning to enable safe evacuation and prompt emergency response.

Fire alarm systems are broadly categorised into two main types: conventional and addressable systems. Additionally, BS 5839 Part 6 provides guidance specific to domestic fire detection and alarm systems (e.g., houses, flats, and HMOs).

1. Conventional Fire Alarm Systems

Description:
A conventional fire alarm system divides a building into multiple detection zones. Each zone is hardwired back to a central control panel. When a detector or call point in a zone is activated, the control panel indicates the affected zone but not the exact device location.

Typical Applications:

• Small      to medium-sized premises (e.g., small offices, shops, schools)
• Where      detailed location information is not critical

Advantages:

• Cost-effective      for smaller buildings
• Simple      to install and operate

Limitations:

• Limited      fault-finding precision — only the zone is identified, not the individual      device
• Requires      more cabling than addressable systems

2. Addressable Fire Alarm Systems

Description:
In an addressable system, each detector, call point, and interface is assigned a unique digital address. When activated, the control panel displays the exact location and type of device in alarm or fault condition.

Typical Applications:

• Large      or complex premises (e.g., hospitals, shopping centres, universities)
• Buildings      requiring detailed control and monitoring

Advantages:

• Precise      location of alarm or fault
• Easier      maintenance and fault diagnosis
• Programmable      cause-and-effect logic for staged evacuation or integration with other      systems

Limitations:

• Higher      initial cost
• Requires      skilled configuration and commissioning

3. BS 5839-6: Fire Detection and Fire Alarm Systems for Domestic Premises (Part 6)

Scope:
BS 5839-6 provides recommendations for the design, installation, commissioning, and maintenance of fire detection and alarm systems in dwellings, including:

• Individual      houses, flats, and maisonettes
• Houses      in multiple occupation (HMOs)
• Sheltered      housing and similar residential accommodation

System Categories:

• Grade      A to F systems – defining the system components (from full control      panels to battery-operated alarms)
• Category      LD (Life protection) and PD (Property protection) systems –      defining the coverage level (e.g., LD1 for all areas, LD2 for escape      routes and high-risk rooms, LD3 for escape routes only)

Typical Systems:

• Interlinked      smoke and heat alarms (mains-powered with battery backup)
• Addressable      systems for large residential complexes or HMOs

4. Installation, Commissioning, and Maintenance

All fire alarm systems in the UK should be designed, installed, commissioned, and maintained in accordance with the relevant parts of BS 5839:

System Type

Relevant British Standard

Non-domestic (commercial/industrial)

BS 5839-1:2017

Domestic (houses, flats, HMOs)

BS 5839-6:2019+A1:2020

Installation

• Systems      must be installed by competent persons.
• Cables      should be fire-resistant and installed to maintain circuit integrity.
• Detectors      and sounders must be positioned according to design drawings and      manufacturer’s instructions.
• Clear      labelling and zone plans must be provided.

Commissioning

• Performed      by a qualified person after installation.
• Includes      testing all devices, verifying correct operation, and ensuring sound      levels and audibility meet requirements.
• Documentation      and certification (in accordance with BS 5839) must be provided upon      completion.

Servicing and Maintenance

• Regular      testing ensures reliability and compliance.
• Weekly      user tests: Manual call points tested alternately across zones.
• Quarterly      and annual servicing: Conducted by a competent service provider.
• Includes      checking detectors, sounders, batteries, logbooks, and control panel      functions.
• Maintenance      records must be kept up to date and available for inspection.

5. Summary

Aspect

Conventional

Addressable

BS 5839-6 (Domestic)

Detection Method

Zonal

Individual (addressed)

Smoke/heat alarms (Grades A–F)

Indication

Zone indicator

Exact device location

Local alarm/interlinked

Typical Use

Small buildings

Large/complex buildings

Homes, flats, HMOs

Standard

BS 5839-1

BS 5839-1

BS 5839-6

Maintenance

Routine inspection per BS 5839-1

Routine inspection per BS 5839-1

Regular testing per BS 5839-6

References

• BS      5839-1:2017+A2:2020 — Fire detection and fire alarm systems for      buildings. Code of practice for design, installation, commissioning and      maintenance of systems in non-domestic premises.
• BS      5839-6:2019+A1:2020 — Code of practice for the design, installation,      commissioning and maintenance of fire detection and fire alarm systems in      domestic premises.
• Regulatory      Reform (Fire Safety) Order 2005 — Governs fire safety in non-domestic      premises.