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BS 5839: fire detection and alarm systems
BS 5839-1 is the design, installation, commissioning and maintenance standard for fire alarm systems in non-domestic premises. Most insurance policies and Fire Authority audits reference it directly. If the design category on your system isn't the right one for the building, every other check is academic.
Category L vs Category M
M = manual only (call points, no automatic detection). L = Life Protection systems with automatic detection. P = Property Protection. Categories are layered:
- L1 — detection throughout all areas, including voids and roof spaces. Highest life-safety category, typical for care homes and HMOs.
- L2 — L3 + detection in specified high-risk rooms.
- L3 — detection on all escape routes and in rooms opening onto them.
- L4 — detection on escape routes only.
- L5 — bespoke; detection in specific areas identified by risk assessment.
Weekly tests — what the standard actually asks for
Test one call point each week, rotating through the building so every call point is tested at least every six months (or every quarter for systems above 50 call points). Note the call point tested and any faults in the logbook. The sounders must operate within 5 seconds.
Six-monthly servicing
BS 5839-1 requires the system to be serviced at least every six months by a competent engineer — typically a BAFE SP203-1 registered company. They inspect at least 25% of detectors at each visit, so every device is tested at least annually.
The design responsibility you may not realise you have
If you alter the building, change its use, or move walls, you change the fire alarm design. The Responsible Person must arrange for a re-survey and, where necessary, additional detection. Building works without an alarm review are a recurring cause of failed fire risk assessments.
Battery and standby supplies
Standby batteries must support the system for 24 hours plus 30 minutes of alarm. Most systems use 5–7 year batteries; record the install date and budget for replacement before they fail mid-test.