Fire Alarm Categories Explained
Posted: 11/05/2023
6 minute read
Fire alarm categories explained
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Fire Alarm Categories Explained

We often refer to The Regulatory Reform (Fire Safety) Order 2005 when it comes to fire alarms, because this is the piece of legislation that requires you to have a detection and alert system that is fit for your specific premises.

That basically means that you can’t just get any old fire alarm — you need one that works for the way your building is structured and for how it’s used. For example, a fire alarm system for a block of four flats will need to be different to one for an office building with ten floors and a warehouse.

And that’s where fire alarm categories come into the picture. But what are they and where do they come from? In this piece, we’re going to cover everything you need to know about fire alarm categories so that you can make a more informed choice and understand the purpose behind them.

Fire alarm categories explained

What is BS 5839?

BS 5839 is the British Standard for the installation of fire alarms and it is this code that defines and classifies the different categories. The code breaks the categories down into three groups to help meet different needs, which we’ll explore next.

This British Standard is separate from the RRFSO, with the latter simply outlining your legal responsibility, while the BS 5839 covers the practical application for fire alarm configuration and layouts.

What are the different fire alarm categories?

As we’ve mentioned, no two buildings are the same, with different risks, purposes and contents meaning a variety of categories are required to cover all needs. BS 5839 breaks fire alarm categories into the following:

  • Category M fire alarms – standing for ‘manual’ fire alarms
  • Category P fire alarms – standing for ‘property protection’ fire alarms
  • Category L fire alarms – standing for ‘life protection’ fire alarms

We’re going to take a look at the category P and L fire alarm systems as these are the more sophisticated and useful to explore.

Category P Fire Alarms

Category P fire alarms place the focus on protecting the property against fire. The main objective is to raise the alarm as quickly as possible for fire services to attend so that as little damage is done as possible to the premises.

Category P1

P1 category fire alarms are designed to position detectors across the whole building for protection. In this system, the aim is to preserve aspects of the building critical to its operation so that a fire can be dealt with swiftly, thereby minimising the impact on the business.

Category P2

P2 category fire alarms are designed to position detectors only in specific, high-risk areas of the building. This is to protect a small portion of the building critical to business operations, such as a server room or somewhere plant machinery is kept.

Category L Fire Alarms

Category L fire alarms are focused on the protection of life within a building, with five different levels to help suit the varying purposes of buildings and how effective the system needs to be.

Category L1

Category L1 offers the most protection, with all areas of the building featuring detectors and a centralised alarm system to alert everyone in the building if there is a fire. This is ideal for large premises where a lot of time is required to evacuate the whole building — care homes and hotels, for example.

Category L2

Category L2 is the next level below L1, with detectors positioned in all high-risk areas – such as boiler rooms or areas with plant machinery – as well as where a room is considered to be part of the evacuation route. This is ideal for alerting anyone working in areas with a higher risk, such as factory buildings.

Category L3

Category L3 is the level below L2, which specifies detectors along escape routes as well as for rooms that adjoin the escape route. This is to help occupants escape safely before their route can be blocked by smoke and flames.

Category L4

Category L4 offers a modest amount of protection, with detectors situated only within the areas of the building that make up the escape route. This is ideal for low-risk premises, ground level-only buildings for example, where it would not take much time to evacuate the premises.

Category L5

Category L5 is focused on more localised risks, with the system situated to tackle a specific area that is more at risk for fires, perhaps because of the hazardous materials contained within a specific area, for example. This can be used in addition to a more modest system elsewhere in the building.

Fire alarm grades

Fire alarm grades

Fire alarms are also broken down by grade, usually defining the level of quality and technology used for the system. Most domestic properties in the UK will use the D-F grade range for fire alarms, while businesses will likely need something in the A-C range.

Grade A Fire Alarm System

This system must comply with the standards set out in BS EN 54, covering the design, installation and the components themselves. It will be formed by individual detectors and sounders, with centralised control and backup power to keep it running.

Grade C Fire Alarm System

This system can be formed of detectors and sounders to be arranged like smoke alarms, featuring centralised control with all power supplied by mains and standby as a backup.

Grade D1 Fire Alarm System

This system is formed by one or multiple fire detectors that are powered by mains but feature standby battery power that is tamper-proof.

Grade D2 Fire Alarm System

The same as above, but featuring battery power for standby that can be replaced by the user.

Grade F1 Fire Alarm System 

This system features one or multiple battery-powered detectors where the batteries are tamper-proof.

Grade F2 Fire Alarm System

This system features one or multiple battery-powered detectors where the batteries can be replaced by the user.

Surrey Tech Services can advise you on the different types of fire alarm categories

Here at Surrey Tech Services Ltd, we’re well-versed in the different fire alarm categories and grades, along with all relevant British Standards. This means that whether you have a building used for commercial purposes, such as an office, or for residential purposes, such as a block of flats, we can install and maintain the system as appropriate. 

Keep your building and occupants safe with adequate fire detection and alert systems from the leading experts in London and the Home Counties – including Maidenhead, Guildford and Slough. Call today and speak to our team about fire alarm systems and our associated services.

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    Call us now on 08081 689 497 to find out more about our fire alarm design, installation and maintenance services.