Answer
Sep 26, 2026 - 12:00 PM
L1, L2, L3, and L4 are categories of fire alarm systems defined in the British Standard BS 5839-1, indicating the level of coverage provided. L1 offers the highest level of protection with detectors in all areas of a building, L2 covers all escape routes and high-risk areas, L3 covers all escape routes and rooms opening onto them, and L4 provides detection only in escape routes. Each level is designed to suit different building risks and requirements for life safety.
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