Answer
May 02, 2026 - 01:17 PM
L1, L2, L3, L4, and L5 are categories of fire alarm systems defined by the British Standard BS 5839-1. L1 provides the highest level of coverage, with detectors in all areas of a building, while L2 and L3 offer progressively less coverage, focusing on escape routes and high-risk areas. L4 and L5 are the most limited, with L4 covering only escape routes and L5 being custom-designed for specific risks.
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