Fire Alarm System Design Code of Practice
	Base Lighting & Fire Ltd offer a full and comprehensive design, commission and maintenance service through a team of fully qualified and experienced engineers. We offer three levels of commissioning, depending on individual customer requirements. At all levels of commissioning we ensure that the system is fully working and is in full compliance of the appropriate BS codes of practice.

CHOICE OF FIRE DETECTORS The main criteria for the choice of fire detectors is the speed to detect possible fires and to minimize false alarms to suit the fire hazard. Heat Detectors may take the form of fixed temperature sensors: these will operate when the set temperature is reached. Rate of Rise heat detectors respond to the rate of rise of temperature. In this case the detector responds when either the temperature rises at more than a certain rate or when the fixed temperature is reached. Ionisation Smoke Detectors detect small particles of smoke or invisible by-products of fire by the reduction it causes in the current that flows between electrodes in an ionization chamber within the detector. These detectors are sensitive to invisible products such as cooking fumes and to avoid false alarms, should not be used near cooking facilities. Optical Smoke Detectors detect smoke by means of a small light source within the chamber. If smoke enters the chamber the light scatter from the smoke particles can be detected. Optical detectors detect visible smoke; for this reason they are used on escape routes where it is important that the fire is detected before the escape route becomes impassable due to visible smoke. Multi-sensor Detectors contain more than one sensor e.g. heat and smoke sensor. The purpose of combining sensors in this way is to enhance the performance of the system in detection of fire and its resistance to at least certain categories of false alarms or both. With some multi-sensor detectors it is possible to disable an individual detection sensor; this might be used in a time related system to reduce false alarms As an example with a heat and optical multi-sensor detector, the optical sensor might be disabled during the day to stop the potential of false alarms. MOUNTING HEIGHT FOR DETECTORS Maximum ceiling height Heat detector rate of rise = 9m Heat detector fixed temp = 7.5m Smoke detector = 10.5m Optical beam = 25m Maximum ceiling height ( 5 minute response time ) Heat detector rate of rise = 13.5m Heat detector fixed temp = 12m Smoke detector = 15m Optical beam = 40m SMOKE DETECTOR SPACING Smoke detector spacing distance into a corner is 7.5m and in a regular square array, in a diagonal of 15m and a side to a square of 10.6m. Smoke detector spacing in corridors becomes greater than 10.6m and approaches 15m because of the way the radiiintersect the width of the corridor. HEAT DETECTOR SPACING Heat detector spacing distance into a corner is 5.3m and in a regular square array, in a diagonal of 10.6m and a side to a square of 7.5m. (Note Heat detectors are not suitable for escape routes). VOID DETECTION Protection of voids is used if the system category is such that automatic fire detection should be provided in any area that contains a horizontal void of 800mm or more in height: automatic fire detection should also be provided in the void. For example this means that in a type L4 system protection should be provided in a void greater than 800mm above an escape route but not necessarily in a void remote from the escape route. Voids less than 800mm in height need not be protected unless, the void is such that extensive spread of fire or smoke between rooms and compartments can take place before detection or on the basis of a fire risk assessment the fire risk in the void is such as to warrant protection of the void.		SITING MANUAL CALL POINTS Distribution of manual call points should be such that no one need travel more than 45 metres to reach the nearest manual call point, measured along the route that a person would actually follow taking into account the layout of walls, partitions and fittings. If at the design stage the final layout of the premises is unknown, the maximum straight line distance of 30 metres between any point in the building to the nearest call point is applied. Manual call points should be located on escape routes and, in particular, at all storey exits and all exits to open air so that it is impossible to leave the storey or the building without passing a manual call point. They should also be sited near any high risks or special hazards e.g. kitchens etc. Manual call point mounting height should be 1.4 metres +/- 0.2 metres above floor level. AUDIBILITY LEVELS In all accessible areas, a minimum of 65dBA or 5dBA above any background noise which is likely to persist for more than 30 seconds should be used. For areas where people are sleeping e.g. a hotel, the sound level at bedhead should be a minimum of 75dBA with all doors closed. Sounder level loss occurs through doors, -20 dBA for a partition door and -30 dBA for a fire door, so allowances must be made for this: for environments where sounders may not be heard, visual flashing beacons may be necessary as well. The premises should only use one type of sounder, e.g. bells and sounders should not be mixed. A fire alarm should emit a visual and audible signal to warn occupants with hearing or visual impairments, e.g. sounder / beacons in toilets and communal areas: this is also required for the Disability Discrimination Act (DDA). Base Lighting & Fire Ltd offer a full and comprehensive design service to guide you through the items covered in this section of fire alarm design. Contact your local engineer or contact the sales office for further help or information. TESTING AND MAINTENANCE (BS5839: PART 1: 2002) Daily Inspection: Check that the charger on indicator shows and inspect for any fault lights showing or sounders operating. Weekly test: Ensure that all indicators show by resetting according to the instructions provided with the panel and check that the internal sounder operates. Test a call point or detector to test the system, check that the sounders operate, then reset the fire alarm panel. Each week test a different zone in rotation so that each zone is tested at least quarterly. Quarterly or six month test: Check all previous log book entries and clarify that any remedial work has been completed. Check the battery and its connections, operate a call point or detector in each zone to test the fire alarm as per above. Remove mains supply and check that the battery is capable of supplying the alarm sounders.

Commissioning
	Documents for the commissioning and Documentation of a system Commissioning Procedure Zone Details Text Details Commissioning T & C's Commissioning Booking Form

Technical
	BS 5839-1 part 1, 2002, Fire detection and alarm systems for buildings – Part 1 : Code of practice for system design, installation, commissioning and maintenance DESIGN CATEGORIES L systems: For the protection of life P systems: For the protection of the property M systems: Manual alarm system intended for protection of life (AFD = Automatic fire detection) (MCP = Manual call points) Type M = MCP Type P1/M = AFD + MCP throughout Type P2/M = AFD where specified + MCP throughout Type L1 = MCP + AFD throughout Type L2 = MCP + AFD AS L3 + specified areas Type L3 = MCP + AFD on escape routes, AFD in rooms opening onto * Type L4 = MCP + AFD on escape routes only * L3: In category L3 systems, heat, smoke or combustion gas detectors should be installed in all rooms that open onto the escape routes, except those rooms opening onto corridors of less than four metres in length need not be protected, provided that fire resisting construction, including fire doors that separate these corridors from any other section of the escape routes. Type L5/M = AFD where specified + MCP throughout * * For this category L5 the person or organization doing the risk assessment takes on the legal responsibility. Category assessment requires in-depth design experience, risk assessment procedures, knowledge of fire safety engineering, (usually a 3 year university degree course), backed up with professional indemnity insurance. The choice of categories should not be expected to be made by the sales engineer/ designer in isolation. The client/ owner/ employer/ insurer may also be part of the decision and consultation process.