Answer
Sep 26, 2026 - 11:59 AM
L1, L2, L3, L4, and L5 are categories of fire alarm systems defined by British Standard BS 5839-1, describing different levels of protection. L1 provides the highest level, with detectors throughout all areas of a building, while L2, L3, L4, and L5 offer progressively reduced coverage, focusing on escape routes, high-risk areas, or specific requirements. The choice depends on the building's use and fire safety needs.
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