The category of a fire alarm system says how much of the building has automatic detection, and why. Here is what each one means in plain English.
Why categories exist
BS 5839-1 uses categories to describe what a fire alarm system is designed to achieve: protecting life (L), protecting property (P), or relying on people to raise the alarm by hand (M). The category is chosen from the fire risk assessment, and sometimes your insurer's requirements, and it decides where detectors go.
The life safety categories
From the least to the most detection:
- Category M: manual call points and sounders only, no automatic detection. People who discover a fire raise the alarm.
- Category L4: detection in the escape routes, such as corridors and stairways.
- Category L3: detection in the escape routes and in rooms that open onto them, so people are warned before a fire blocks their way out.
- Category L2: everything in L3, plus detection in other areas the fire risk assessment identifies as higher risk.
- Category L1: detection throughout the building, giving the earliest possible warning.
- Category L5: a system designed to meet a specific fire safety objective that the other categories do not cover.
The property protection categories
Category P2 covers defined parts of the building where a fire would be costly, such as a stock room or server room. Category P1 covers the whole building. Insurers sometimes ask for a P category in warehouses and other buildings with valuable contents, and it is often combined with a life safety category.
Which do you need?
Your fire risk assessment should say. As a broad picture, buildings where people sleep, such as care homes and hotels, usually need L1 or close to it; many offices and shops have L2 or L3; and some small, simple premises are suited to M with manual call points. Homes and HMOs are covered by BS 5839-6 instead, with its own grades and LD categories.
Changing category
A change of use, a new fire risk assessment or an insurer's request can mean upgrading the category. That usually means adding detectors to the existing system, and sometimes a larger panel. We survey the building, design to the new category and give a fixed price. Call 020 8946 5567 for a free survey.
Need help with this in London?
Security Red Alert covers all 32 London boroughs from our Summerstown SW17 office. Explore our Fire Alarm Installation, Home Fire Alarms, Fire Extinguishers and Emergency Lighting Testing services, or call 020 8946 5567 for a free survey.