If you run a business or manage a commercial building, BS 5839-1 is the standard your fire-alarm system is designed and maintained to. Here’s what it means, the system categories, and what you need to do.

What BS 5839-1 is

BS 5839-1 is the British Standard code of practice for the design, installation, commissioning, and maintenance of fire detection and alarm systems in non-domestic premises — offices, shops, factories, warehouses, hotels, and the like.

It sits alongside the Regulatory Reform (Fire Safety) Order 2005, which legally requires a fire risk assessment and appropriate fire detection in commercial premises. BS 5839-1 is how you meet that in practice. (For homes, the equivalent is BS 5839-6 — see the difference below.)

The system categories

BS 5839-1 classifies systems by their purpose — this determines how much of a building is covered:

Category M — manual systems

• Manual call points (break-glass) only, no automatic detection. Relies on people raising the alarm.

Category L — life protection (automatic detection to protect people)

• L1 — detection throughout the entire building (maximum protection)
• L2 — escape routes + rooms opening onto them + defined high-risk areas
• L3 — escape routes + rooms opening onto them
• L4 — escape routes only
• L5 — a custom/localised system for a specific risk

Category P — property protection (automatic detection to protect the building)

• P1 — detection throughout the whole building
• P2 — detection in defined high-risk areas

Your fire risk assessment determines the category your premises needs.

BS 5839-1 vs BS 5839-6

A common point of confusion:

• BS 5839-1 = non-domestic (commercial) fire-alarm systems — the categories above.
• BS 5839-6 = domestic premises (homes, HMOs) — uses grades (e.g. Grade D interlinked mains alarms) rather than these categories.

So a shop uses BS 5839-1; a house or HMO uses BS 5839-6. See our smoke alarm regulations guide for the domestic side.

Testing and maintenance

BS 5839-1 sets out a maintenance regime, typically including:

• Weekly test — a manual call point tested (a different one each week) to confirm the system sounds
• Periodic servicing — professional inspection and testing, usually at intervals through the year (commonly six-monthly)
• A log book recording tests, servicing, faults, and false alarms

Like emergency lighting, the records are what evidence your compliance to a fire officer or insurer.

What businesses should do

• Have a fire risk assessment that determines your required system category
• Ensure the system is designed and installed to BS 5839-1
• Keep up the weekly tests and periodic servicing, with a log book
• Address faults and reduce false alarms promptly

Many businesses fold this into a planned maintenance contract alongside emergency lighting and EICRs — see our commercial maintenance service.

Get BS 5839-1 fire detection sorted

GFL Electrical design, install, and maintain commercial fire-alarm systems to BS 5839-1 across East London — to the right category for your premises, with proper records. See our fire & smoke alarm service or call 020 3774 5604.