Selection, Installation and Maintenance of Automatic Fire Detection and Alarm System Code of Practice
2008 Edition

IS 2189 advises selection of fire detectors based on the nature of fire hazards, environmental conditions, and desired response time. For smoldering fires such as those involving wood or textiles, smoke detectors—including optical types—are recommended. Fast flaming fires with small particles are better detected by ionization smoke detectors or heat detectors. Multi-sensor detectors can improve accuracy by combining different sensing technologies. Special detectors like flame detectors are suitable for high-ceiling or open outdoor spaces, while aspirating detectors are ideal for challenging environments requiring high sensitivity.

According to IS 2189, smoke detectors on flat ceilings should be spaced so that no point is more than 7.5 meters from a detector, while heat detectors should have a maximum spacing of 5.3 meters. For sloped ceilings with apex heights exceeding 600 mm, smoke detectors should be spaced between 7.5 and 8.5 meters near the apex. Detectors must be placed at least 500 mm away from walls, structural beams, or obstructions deeper than 250 mm, and twice the obstruction depth when shallower. Additionally, a clear space of at least 500 mm should be maintained beneath detectors to ensure effective detection.

IS 2189 specifies that conventional fire detection systems require independent wiring with separate cables connecting detectors and manual call points to zone panels, with each zone typically covering up to 2000 square meters. Addressable systems use Class A (return loop) wiring for signalling line circuits, allowing devices to be individually identified on the loop. Partially addressable systems employ zone addressable modules to integrate non-addressable devices. Zoning ensures quick identification of fire location, and wiring must be separate from other building systems to prevent interference.

IS 2189 mandates regular maintenance and testing to guarantee reliable fire detection system operation. Users should ensure routine servicing, either through service contracts or trained personnel. Quarterly inspections involve logbook reviews, battery testing, alarm function checks, and visual inspections for damage or moisture. All defects must be documented and addressed promptly. Periodic cleaning and sensitivity tests are essential, with schedules generally set at quarterly or semi-annual intervals according to manufacturer and code guidelines.

The standard prioritizes early smoke detection to safeguard lives, setting thresholds for alarm activation before smoke density or toxic gas concentrations reach hazardous levels. Smoke detectors on escape routes must trigger alarms at very low smoke densities to provide sufficient evacuation time. To minimize false alarms, especially for systems linked to automatic fire suppression, IS 2189 requires confirmation of fire presence by at least two independent detectors before initiating automatic actions. Moreover, fire detection systems must operate independently to prevent interference that could cause false activations.