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Fire Alarm System Categories

The choice of a fire alarm system depends upon many criteria, but specifically the building type and its construction, the purpose of use, and the current legislation. Where new and altered buildings are concerned fire safety is the duty of the owner of the building, but the responsibility for checking that the building regulations have been observed is down to local building control or an approved Inspector from the private sector.

Fire alarm systems all fall within the standards defined in BS5839, either Part1:2017 which is the code of practice for design, installation, commissioning and maintenance of systems in non-domestic premises, and Part 6:2013, which is code of practice for the design, installation, commissioning and maintenance of fire detection and fire alarm systems in primarily for domestic properties. Both of these have several categories/levels, which can cause confusion, especially if you have not had a proper fire risk assessment performed and a suitably qualified person has provided the appropriate guidance.

Understanding Categories

The primary code of practice for designing, installing, commissioning, and maintaining fire detection and alarm systems in non-domestic buildings is BS5839-Part1:2017. The standard defines where fire alarm system components such as manual call points and detectors should be positioned, based on the objective the system is required fulfil. These are known as Categories

The Categories are:

  • M - meaning manual
  • L - meaning for the protection of life
  • P - meaning for protecting property

It is very common, and still complies with the standard, for a fire alarm system installed in a building to incorporate more than one element of a category.  This configuration is typical in a HMO or building consisting of a number of individual flats.

Category M

Category M is the simplest and least responsive of the categories. This requires manual intervention in activating an alarm device to provide alert of an emergency. This is generally recommended where a traditional fire alarm system with automatic fire detection is not suitable and the occupants would be more likely to be aware of a fire quicker.

Category L

Category L systems are automatic fire detection and alarm systems with the aim of protecting life. There are 5 levels within this category, each offering a different level of fire protection.

Category L1

L1 systems are designed and installed to provide the highest level of protection specifically for life. The specification incorporates manual call points (MCPs) and automatic fire detection AFD)that has to be installed throughout the every part of a building. For the fire detection attention attention should be taken to choose the detector types according to not only the fire risks in each room, but also the persons at risk. For example, heat detectors should not be the primary detector type in bedrooms as they will not provide quick enough warning to protect the occupant's life.

Category L2

Fire alarm systems that fall into this category feature smoke detectors in all rooms that form part of an escape route, including corridors. Detectors also need to be installed in all high-risk rooms, such as kitchens, boiler rooms and areas with heavy plant machinery.

Category L3

Standard life protection systems feature detectors in all escape routes and rooms that open onto an escape route. The objective of this system is to ensure that all inhabitants of the building are given enough warning to escape a fire, before their exit is impeded by the presence of flames, smoke or toxic fumes.

Category L4

An L4 category fire alarm system consists of detectors within escape route areas only, such as in corridors and stairways. Any circulation areas that make up part of the escape passage should also be fitted with a detector when the site is classed within this fire alarm category.

Category L5

L5 fire alarm category systems are those that are installed to tackle a specific fire risk in a certain area of a building. For example, if there is a room in a building that poses an exceptional hazard because of the items stored there or business activities carried out there.

Category P1

A P1 fire alarm system involves installing detectors in all areas of the building. The objective of a system like this is to protect buildings that are critical to the operations of a business.

Category P2

In a category P2 fire alarm system, fire detectors are installed in high risk areas only. Whilst a system like this does not provide the same level of cover as a P1 solution, it does provide early detection for the most likely sources of a fire.