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Fire alarm engineer inspecting an alarm panel in a commercial building

BS 5839-1:2025 Clause 4; BS 5839-6

System Categories

A compact map of non-domestic life/property categories and domestic grades and coverage categories.

Non-domestic systems

M
Manual call points only; no automatic detection.
L1
Automatic detection throughout, aimed at the earliest warning for life safety.
L2
L3 coverage plus defined higher-risk or specified areas.
L3
Escape routes and rooms opening onto those routes.
L4
Escape routes and circulation spaces only.
L5
An engineered system designed around a specific life-safety objective.
P1 / P2
Property protection throughout / in defined higher-risk areas.

Categories can be combined. The category should come from the fire strategy and risk assessment, not from this summary alone.

Domestic systems

Grades A, C, D1/D2, F1/F2
Describe the power, control and standby arrangement of the alarm system.
LD1
Circulation areas and all rooms or areas.
LD2
Circulation areas plus defined higher-risk rooms.
LD3
Circulation areas forming escape routes.

Domestic systems are covered by BS 5839-6 rather than BS 5839-1.

Source context: BS 5839-1:2025 Clause 4; BS 5839-6. This page paraphrases the app’s quick-reference material and does not reproduce or replace the standard.