Fire Risk Assessment & Fire Alarm System Design

A fire alarm system should never be selected simply because it is the cheapest or most commonly installed option. The appropriate system depends on the characteristics of the premises and the risks identified through the fire risk assessment.

Before a system is designed, engineers may need to consider:

• Building size, layout and construction.
• Number of occupants and occupancy profile.
• Sleeping or non-sleeping accommodation.
• Evacuation strategy and escape routes.
• Sources of ignition and combustible materials.
• Areas presenting increased fire risk.
• Environmental conditions such as dust, steam or fumes.
• Existing fire detection and alarm infrastructure.
• Business-critical equipment and high-value assets.
• Requirements for interfaces with other building systems.

The objective is to provide an appropriate level of detection and warning without creating unnecessary unwanted alarms or installing equipment that is unsuitable for the environment.

Commercial Fire Alarm System Types

There are several different approaches to commercial fire alarm design. The choice between conventional, addressable, wireless or networked systems depends on the building and its operational requirements.

Fire Detection Technologies & Devices

The effectiveness of a fire alarm system depends heavily on selecting the correct detection technology for each environment. A smoke detector that performs well in an office may be unsuitable for a dusty warehouse, commercial kitchen or plant room.

Smoke Detectors

Smoke detectors are widely used because smoke is often produced during the early stages of a developing fire. Their suitability depends on the environment, expected fire characteristics and potential sources of unwanted alarms.

Heat Detectors

Heat detectors respond to temperature conditions rather than smoke. They can be appropriate in areas where normal environmental conditions could make smoke detection unsuitable.

Multi-Sensor Detectors

Multi-sensor detectors combine different detection technologies to improve detection performance in appropriate environments and can assist in managing the risk of unwanted alarm signals.

Manual Call Points

Manual call points allow an occupant to raise the alarm when a fire is discovered. Their location, accessibility and installation are important parts of the overall system design.

Sounders & Visual Alarm Devices

Audible and visual warning devices are used to alert occupants to a fire alarm condition. The required arrangement depends on the premises, occupancy and system design.

Commercial Fire Alarm Installation: Project Life Cycle

A professional fire alarm installation should follow a controlled process from initial assessment through to commissioning and handover. Poor design or incomplete documentation can create problems long after the installation has been completed.

Commercial Fire Alarm Testing, Servicing & Maintenance

A fire alarm system is not a fit-and-forget installation. Routine inspection, testing and maintenance are essential to identify faults, maintain system reliability and demonstrate that appropriate fire safety arrangements are being managed.

Maintenance activities may include:

• Testing automatic fire detectors.
• Testing manual call points.
• Checking sounders and visual alarm devices.
• Inspecting the fire alarm control panel.
• Checking standby batteries and power supplies.
• Testing interfaces and cause-and-effect functions where applicable.
• Investigating fault conditions.
• Reviewing unwanted alarm signals.
• Checking system documentation and records.
• Identifying defects requiring remedial action.

The appropriate frequency and extent of servicing should be determined in accordance with the applicable standard, system design, manufacturer requirements and the circumstances of the premises.

Reducing Unwanted Fire Alarm Signals

Unwanted fire alarm signals can cause significant disruption to commercial operations and may lead to complacency if occupants become accustomed to repeated alarms. They should therefore be investigated and managed as part of effective fire alarm maintenance.

Common causes include:

• Dust and airborne particles.
• Steam and condensation.
• Cooking fumes.
• Aerosols and chemical vapours.
• Unsuitable detector selection.
• Incorrect detector positioning.
• Changes to the building or its use.
• Equipment faults or contamination.
• Inadequate maintenance.

Where repeated unwanted alarms occur, simply resetting the panel does not address the underlying issue. A competent assessment should establish the cause and determine whether changes to equipment, positioning, programming, maintenance or building management are appropriate.

Fire Alarms as Part of a Wider Life Safety Strategy

A commercial fire alarm system should be considered as one component of a wider fire safety strategy. Early detection is only effective when it is supported by appropriate evacuation arrangements and other fire safety measures.

Depending on the premises, the wider strategy may include:

• Fire risk assessments.
• Emergency lighting.
• Fire doors and compartmentation.
• Fire safety signage.
• Emergency evacuation procedures.
• Fire extinguishers and firefighting equipment.
• Smoke control systems.
• Staff fire safety training.
• Routine inspection and maintenance programmes.

Coordinating these elements helps create a more comprehensive approach to protecting occupants and maintaining the safety of commercial premises.

Commercial Fire Alarm Systems FAQs

What is BS 5839-1:2025?

BS 5839-1:2025 is the current British Standard covering the planning, design, installation, commissioning and maintenance of fire detection and fire alarm systems in non-domestic premises. It replaced BS 5839-1:2017 in April 2025.

Does every commercial building need a fire alarm system?

There is no single fire alarm specification that applies to every commercial building. Fire safety measures should be determined according to the circumstances and risks of the premises, including the findings of the fire risk assessment and the building's occupancy and use.

How often should a commercial fire alarm be serviced?

Commercial fire alarm systems require routine inspection, testing and maintenance. The appropriate regime depends on the system, premises, risk profile, manufacturer requirements and applicable standards. A competent fire alarm specialist can establish an appropriate maintenance programme.

What is the difference between conventional and addressable fire alarms?

A conventional system generally identifies the zone in which an alarm or fault has occurred, whereas an addressable system can identify the individual device reporting the condition. Addressable systems are therefore particularly useful in larger or more complex premises.

Are wireless fire alarm systems suitable for commercial premises?

Wireless fire alarm systems can be suitable for certain commercial applications, particularly where installing traditional cabling would cause significant disruption or where the building presents challenging installation conditions. Suitability should always be determined through appropriate system design.

What is cause-and-effect in a fire alarm system?

Cause-and-effect describes the programmed actions that occur following particular fire alarm or fault conditions. For example, a fire alarm activation may trigger door release, lift control, ventilation shutdown or other building system interfaces where required by the system design.

How can unwanted fire alarms be reduced?

Repeated unwanted alarms should be investigated to establish their cause. Potential solutions may include changing detector types, relocating devices, improving maintenance, addressing environmental conditions or modifying system programming where appropriate.

What documentation should be retained for a commercial fire alarm?

Relevant documentation can include design information, installation and commissioning records, certificates, service reports, test results, fault records, drawings and cause-and-effect information. Keeping accurate records supports ongoing fire safety management.

Can an existing commercial fire alarm system be upgraded?

Existing systems can sometimes be upgraded or modified, depending on their age, condition, compatibility and the requirements of the premises. A professional assessment should establish whether upgrading the existing installation is appropriate or whether replacement would provide a more suitable solution.

What other life safety systems should be considered alongside a fire alarm?

Depending on the premises, other measures may include emergency lighting, fire doors, compartmentation, fire extinguishers, fire safety signage, smoke control, evacuation procedures and fire risk assessments. The appropriate measures should reflect the risks and characteristics of the building.