How much do you know about BS5839? Part 1 of BS5839 (British Standards) is the code of practice for the design, installation, maintenance and commissioning of fire protection alarms and systems for use in non-domestic/commercial premises. If you are a business owner, this is the essential fire safety standard you are required to follow to achieve regulatory compliance with the fire safety regulations in the UK. Our easy to understand guide on BS5839 will walk you through all there is to know, including the fundamental implications on your day-to-day commercial ventures.

Who Is Required to Abide By BS5839?

The non-domestic/commercial premises referred to in BS5839 Part 1 includes shops, offices, hotels, restaurants, hospitals, schools, universities and many other public places. Interestingly, it also includes any communal area of domestic dwellings – such as hallways, corridors and stairwells – where multiple people may be affected by a fire within a common location. This is why, if you are the responsible person for a commercial building, whether it’s an office building, a kitchen or a factory, you should familiarise yourself with the requirements of BS5839 to ensure that you have completed your legal duties.

Why is a Fire Alarm System or Fire Detection System Needed?

Within the Foreword of BS5839 (pp iv-vi), it is stipulated that: “National building regulations require fire detection and fire alarm systems to be installed in many buildings at the time of construction. In addition, legislation requires that, where necessary to safeguard relevant persons in case of fire, existing premises are equipped with “appropriate fire detection and fire alarm systems”. The guidelines also provide a non-exhaustive table demonstrating examples of non-domestic premises for the purpose of practicality, which is found in Annex A (pp 130-131). The table gives the commonly expected examples of public places and buildings that BS5839 may apply to, but it does not strictly enforce that all premises found within the table “are required by law to have such systems installed” (p v-vi). Generally, it is advisable to abide by the best practices when approaching fire safety on any non-domestic/commercial premises, always starting with a fire risk assessment that can determine the overall fire safety of a location, as well as if a fire detection or fire alarm system is beneficial or required and which type would be the most appropriate.

Fire Alarm and Fire Detection Systems: Defined

Various fire detection systems and fire alarm systems exist to protect premises of multiple sizes and use-cases. Systems range from basic, rudimentary designs which require manual input to alert others of fire, to high-tech wireless fire detection systems. You should also be aware that Part 1 of BS5839 does not refer to the systems which have a primary purpose of controlling or extinguishing fire (such as fire extinguishers and sprinklers), nor does it cover:
  • Systems that combine fire alarm functions with function not relating to fire alarms
  • Voice alarm systems
  • Emergency service call systems
  • Audiovisual guidance systems (i.e. emergency lights)
When determining what alarm or fire detector type is suitable for your premises, Annex A of BS5839 refers to various categories of systems and the type of premises they are most appropriate for.

What are the Categories of Systems and Alarms?

The BS5839 Part 1 recommends types of alarm and detection systems based on the location and objective of the systems – referred to as Categories/

Category L Systems

Category L systems are charged with protecting life, with the focus on prioritising areas of high fire risk, escape routes and fire exits. Category L systems levelled: the lower the number, the more protection the category L system corresponds to.

Category L5 – Specific Design

Category L5 systems do not strictly conform to the requirement of the other for L categories, instead, they are systems that are designed around very specific requirements particular to the location and other risk factors highlighted by the fire risk assessment.

Category L4 – Escape Routes

This refers to fire detection systems that have been installed only on escape routes and not inner rooms.

Category L3 – Escape Routes and Any Rooms Opening Onto Escape Routes

A commonly found fire alarm system in public buildings and premises, these systems typically include smoke detectors on every escape route, as well as every room that connects to escape routes.

Category L2 – Escape Routes, Rooms Opening Onto Escape Routes and High-Risk Inner Rooms

Category L2 systems can be considered similar to the L3 but with the added scope of including inner rooms determined as “high-risk”, without the requirement of the room having to be connected directly to an escape route. Such rooms are deemed as at a high enough risk of fire that they require dedicated fire detection.

Category L1 – Complete Coverage Protection

Requiring manual call points, automatic fire detection and fire detectors in every room, category L1 buildings require fire detection systems throughout the entire premises, typically used in buildings that house a higher proportion of vulnerable people through its primary usage. When calculating for an L1 system, a “room” is anything over 1 metre squared.

Category M Systems

Manual-only systems, these premises require manual call points to be installed on all corridors and exits, where people do not have to walk more than 45m before reaching a call point. Interestingly, all category L systems begin as an M system and then level up to an L system when fire risk assessments deem it appropriate and necessary. System M-only will typically be found in kiosks, sub-buildings, small buildings and buildings which are barely occupied.

Category P Systems

Category P systems are those which are designed for property protection (not life protection) as their primary purpose. These systems are far rarer than category L and M systems, specifically because most buildings have some sort of human occupancy at all times, even if just a night watchman/security guard. P category systems are typically installed in unoccupied buildings, such as unmanned warehouses, as such, these systems will be connected to Alarm Receiving Centres (ARCs) and signal a call to the Fire Services to attend to any blaze.

Category P1

Automatic fire detection systems installed in all areas of the building, a category P1 system will be used to detect any signs of fire as soon as reasonably possible.

Category P2

P2 systems will not have automatic fire detection systems installed in every area of the building, instead, the only parts of the premises outfitted with a P2 system will be the ones determined as a high fire risk by a fire risk assessment.

Primary Design Decisions to Consider When Selecting the Most Appropriate Fire Alarm and Detection Systems

The legislation also highlights numerous design considerations, including the most appropriate system category for certain building types and their fire safety requirements. The recommendations found within the legislation provide clear guidelines and advice to consider, with reference to the British Standards.

Type of System

Here, the category of the property will typically determine the category of fire detection and alarm systems required, detailed by a thorough fire risk assessment, as written on p17 of the BS5839.

System Components

All components selected to be used as part of the overall system installed/intended to be installed must conform to British Standards or Harmonised European Standards and should be tested against these standards.

Detection Zones

Dividing the building into detection zones which are commonly installed with manual call points or automatic detectors to guarantee that fire responders are alerted to the specific location of the fire. These are appropriate for all building types, bar the smallest.

Monitoring and Reliability of the System

The design of the system should be done so to limit the scope and effect of any fault of the system: if there is a fault, there is required to be an alert system in place to inform the necessary parties of a need for maintenance or replacement.

Alarm Zones

Complex buildings require a fire emergency evacuation plan (FEEP) that sometimes includes a phased evacuation process, requiring separate alarm zones. The guidelines recommend that, at the boundaries of each separate alarm zone, the construction should be composed of fire-resistant walls.

Direct Communication with Fire and Rescue

Some systems will require a direct alert system with fire and rescue services, some will not, Category L and M systems do not require an automatic connection to the emergency services as a telephone call is adequate. Where buildings are always occupied, an automatic communication system may be appropriate.

Audiovisual Alarm Systems and Warnings for the Hearing Impaired

All alarm systems must be adequate to warn all people as intended. Where appropriate, it may be advisable to include visual representations of an alarm, as well as an audible one, for those who are hearing impaired. For buildings with sleeping quarters, it may be necessary to add tactile devices under pillows or mattresses that are connected to the fire alarm system.

Manual Call Points

All manual call points must be explicitly placed and easily discernible from non-call points, whilst being distributed in such a way that it is absolutely impossible to exit a building or transfer to a different floor or building without passing at least one.

Fire Detector Types

All fire detectors must be designed to detect at least one (or more) component of fire:
  • Combustion gas
  • Heat
  • Infrared/Ultraviolet radiation
  • Smoke
Multi-sensor fire detectors also exist to detect fire via multiple sensors and ways. Other important factors to consider – particularly in light of recommendations from the fire risk assessment – are:
  • Speed of detection/response
  • Minimising of false alarms
  • Nature of any fire hazard present

Installation Issues

Some very basic guidelines and principles should be followed when designing and installing new fire detection and alarm systems.

Compliance Responsibilities

Crucially, under Section 4 of BS5839 Part 1, one organisation must have accepted responsibility within the section. In short, even though multiple parties could be involved from the design process all the way through to the installation and final handover, one party must still have accepted overall responsibility for compliance: such as a fire risk assessment company, who can suggest and sell fire alarm and detection systems, but contracts out the installation process to a third party.

Limiting False Alarms and False Fire Alarm Signals

Section 3 of BS5839 stipulates that false alarms must be limited as much as possible, in terms of their design and installation: for example, installing a smoke detector in a bathroom should be avoided.

Once Installed

The handover of fire detection and alarm systems is covered on pages 109-116 of the Standard, detailing the completion of the process from initial survey to final signoff. Post-installation has several phases, detailed below.


This process comprises a complete and comprehensive test of the installation, along with the recommendations of the standard, as well as the system specification via the designer’s requirements. P 4, 109 details that all tests and work must be performed by a competent person: with relevant education and experience, up-to-date training and the ability to perform all tasks with reference to all reference materials and design drawings.


All records and pertinent documentation must be provided to the end-user of the system, as part of the commissioning process. One article of documentation that is crucial to hand over to the end-user is that of the most accurate “as-fitted” systems drawings, maintenance manuals and system-specific operation documents. Other important documentation required for handover purposes include:
  • Installations and commissioning of the system
  • Relevant records
  • Logbook for all system events
  • Relevant records – such as those detailing variations on the original design specification

BS5839 Certification

Once the commissioning of the system has been complete, certificates are to be granted for all three distinct setup stages: design, installation and commissioning. P 133 specifies that individuals or organisations who carry out each certification must be competent enough to verify that the recommendations – of the Standard – have been satisfied, or not. After all, certifications have been completed, a formal handover to the purchaser/end-user can be performed. At this stage, crucially, the company that has agreed to bear contractual responsibility for the system provides a certificate of acceptance to the end-user. After handover has been finalised – as well as the final stages, such as certification – the daily running and maintenance of the system falls to the management of the property that the system is installed in. The maintenance section of the Standard is found on pp 117-127.

Fire Alarm System Maintenance & Testing

All fire alarm systems are subject to regular fire alarm testing procedures, as described below:

Weekly Maintenance

P 117 recommends five practices to maintain on a weekly basis, for the maintenance of the system:
  1. Testing the operation of the manual call point during working hours
  2. Test to be performed at approximately the same time every week
  3. Extra tests a least once per month for those employees who are not present during the weekly test
  4. For those systems with multiple manual call points: a different one must be tested each week
  5. Routine tests should be no longer than one minute so that employees and other occupants can distinguish between tests and real fire alarms

Monthly Maintenance

The Standard features two recommendations for the monthly assessment of the system, which is found on p 188:
  1. For systems with a standby power supply that are utilised via an automatic generator, the generator should be tested on a monthly basis
  2. Standby power which is provided by vented batteries, the batteries should receive a visual inspection. Additionally, the vented batteries and their connections would be inspected quarterly by a competent person (in battery installation and maintenance).

The Importance of Fire Alarm Systems Maintenance

Even the most advanced fire alarm and detection systems will need routine maintenance and human inspection to ensure consistent performance and reliability. Three key reasons to maintain and test your system include:
  1. Familiarise employees and other occupants with the fire alarm
  2. Determine all faults which have been signalled and rectify them appropriately
  3. To eliminate the possibility of major faults or failures within the system
As fire inspection and maintenance are specialist jobs, they are typically performed by an expert, third-party contractors in fire alarm servicing, who can demonstrate their competence by way of third-party certification.

Servicing and Inspection of the System

It is crucial that inspection and servicing are carried out on the system, in addition to the weekly and monthly maintenance inspections: this is to locate any faults, rectify them appropriately. To maintain compliance with BS5839-1, the period between inspection and servicing of the system should not exceed six months, with absolutely no latitude for flexibility on this timeframe.

Responsibility of the System and Premises

The core aim of any fire detection and alarm system is the protection of life and property: maintenance, testing and inspections are crucial to the system functioning, pursuant to the objective. Without prior planning, the process of maintenance can get messy, which is why the Standard recommends that a company nominates a single point of contact, from the premises management team, to “supervise all matters pertaining to the fire detection and fire alarm system”. Responsibilities of the nominated person include:
  • Record keeping of system records and other relevant documentation
  • Ensuring the system is protected against developments that may impact negatively prior standard of protection it offered or contributed to false alarms
  • Providing clear evidence of compliance with fire safety legislation
  • Maintaining fire safety knowledge of employees and other occupants of the premises via fire safety training
The system logbook is a document of crucial importance, this should include the details of the delegated fire safety manager, as well as record each event that is relevant to the system – scheduled, or not, P 129 specifies that real-time amendments of the logbook are helpful to those parties who may conduct inspection or maintenance on the system, as well as those delegated as fire safety management/supervisor in the future. Armed with this summarised BS5838 guide, you should feel more confident handling your fire safety responsibilities at work but if you require any more help, please feel free to get in touch with the Cardinal Fire team for advice today.