Fire Alarms

10 articles

BS 5839-1 Fire Alarm Standard: Design, Installation, Commissioning and Maintenance Requirements for Non-Domestic

Code of practice for fire detection in non-domestic buildings; categories M/L1–L5/P1–P2; smoke detector 10.6 m centres/7.5 m from wall; heat detector 7.5 m centres/5.3 m from wall; FP cable for circuit integrity; commissioning certificate mandatory; referenced by Approved Document B
Fire Alarm Categories L1–L5 and M: What Each Category Means, Risk Assessment Basis and Specifying the Right System

M (manual only); L5 (specified areas); L4 (escape routes only); L3 (escape routes + adjacent rooms); L2 (escape routes + high-risk areas); L1 (whole building — sleeping risk mandatory); P1/P2 property protection layers; FRA-led selection; departure from FRA requires written acceptance
Fire Alarm Commissioning Procedure: Visual Inspection, Functional Test, Cause-and-Effect Verification and Handover

Visual inspection before power; every detector individually tested (aerosol/heat generator); every call point with test key; sounder levels measured (75 dB(A) occupied; 65 dB(A) pillow); cause-and-effect fully verified; commissioning certificate + as-fitted drawings + maintenance log at handover
Fire Alarm Detector Types: Optical Smoke, Ionisation, Heat, Multi-Sensor and Beam Detectors — When to Use Each

Optical smoke (smouldering fires; false alarm from steam/dust); heat A1 54–65°C (kitchens, plant); multi-sensor optical+heat (best false alarm rejection, sleeping areas); beam (warehouses, atriums >10.5 m); ASD Class A (data centres, museums); CO detector BS EN 54-26 (sleeping risk)
Fire Alarm False Alarm Management: Confirmed Alarm Systems, Investigation Zones and CFOA Guidance

95%+ FRS responses are false alarms; BS 5839-1 Annex C decision framework; alarm confirmation (investigation alarm → second device for full alarm); coincidence detection not for sleeping risk; NFCC can suspend AFBR; multi-sensor and Class A detectors reduce UAS
Fire Alarm Interface with Other Systems: Door Holders, Air Handling, Sprinklers, Lifts and Access Control

Door holders fail open on alarm (BS EN 1155); AHU shutdown on alarm (not smoke control systems); sprinkler flow/tamper inputs; lift recall to ground floor (BS EN 81-72); access control release on fire exits (RR(FS)O); gas suppression via suppression panel (never direct); all interfaces in cause-and-effect schedule
Fire Alarm Wiring Topologies: Conventional vs Addressable, Radial vs Loop and Cable Specification

Conventional radial (zone-level only; EOLR monitoring); addressable Class B (device-level; radial); addressable Class A (loop; tolerates single cable break); FP200 Gold 1.5 mm² for integrity circuits (60 min at 850°C); LSZH red sheath; screen at panel end only
Fire Alarm Zoning Design: Maximum Zone Size, Single-Floor Zones, Stairwells and Coincidence Detection

Max 2,000 m² per zone; one floor per zone (except stairwells); 60-second search rule often more limiting than area limit; stairwells one zone per stairwell; coincidence detection (double-knock) — never in sleeping risk or unattended premises
Manual Call Point Siting: Travel Distance Rules, Height, Visibility and Dual-Action Units in Care Settings

Max 45 m travel distance (30 m high-risk); 1.4 m mounting height (1.2–1.5 m range); at every storey exit and final exit regardless of distance; dual-action MCPs for care homes, mental health, schools; key-resettable in secure mental health units (no glass fragments)
NSI and BAFE SP203-1 Certification: What Third-Party Certification Requires and Its Importance for Insurance

BAFE SP203-1 and NSI Fire Gold are the UK third-party certification schemes for fire alarm companies; ISO 9001 QMS required; modules D/I/C/M/H; FIA Level 4 Diploma for competent person; Certificate of Conformity issued at handover; insurers and FRS increasingly require SP203-1