201. It is important that an outbreak of fire in the premises should be detected at an early stage so that the occupants are alerted and the emergency fire action plan implemented as soon as possible. There should also be a means so that anyone in the premises who discovers a fire, can alert others to the existence of the fire.
202. In some small offices, shops and similar premises, a fire may be obvious soon after it starts. In such cases and where travel distances are short, a shouted warning of 'FIRE' or a simple manually operated device, such as a gong that can be heard throughout when operated from any single point within the building, may be all that is needed.
203. In larger premises, particularly those with more than one floor or that are multi occupied, where a shout or warning sounded from a single point will not be heard throughout, an electrical fire alarm system incorporating sounders and manually operated call points is likely to be required.
204. In large or complex premises, particularly those accommodating large numbers of people, such as department stores and shopping centres, a more sophisticated fire alarm system may be required.
205. Where the layout of the premises is such that a fire could develop to the extent that escape routes could be affected before the fire is discovered, it may be necessary for the fire alarm system to incorporate automatic fire detectors to ensure an early warning. This may be the case where there are unoccupied areas or common corridors and circulation areas in multi-occupied buildings or where people work alone and might not see a fire; but the need for the provision of automatic fire detection will be influenced by the means of escape available.
206. Automatic fire detection is only required under fire safety law when it is needed to safeguard life. In addition to the example in paragraph 205 above, other examples of the use of automatic fire detection for life safety are:
207. Some of the features of a fire alarm system may be:
208. Manual call points, often known as 'break-glass' call points, enable a person who discovers a fire to operate the fire alarm and immediately raise the alarm and warn other people in the premises of the danger.
209. Automatic fire detectors. The choice of type depends on the nature of the hazard, the required speed of system response and the need to avoid false alarms. The common types of automatic fire detector are:
210. Sounders are provided to alert occupants. In all cases, the sounders of a fire alarm system should be capable of alerting the staff. As an alternative to conventional sounders, a specially designed voice alarm may be suitable for some premises. Voice alarm systems can provide significant benefits in terms of reduced response time and improved information dissemination.
211. Where there are staff with hearing impairment to the extent that the fire alarm sounders cannot be perceived, then it will be necessary to consider whether there is a need to provide tactile and/or visual alarm devices for those persons.
212. The control and indicator panel provides the facility for indication of fire or fault signals and manual controls such as silencing and resetting. The fire alarm control and indicator panel should be sited at a location which is appropriate for staff and Fire and Rescue Service use taking account of the fire and evacuation strategy that is adopted for the building.
213. When a fire alarm system operates, the evacuation strategy may require that the source of the actuation be quickly identifiable. To achieve this, the building should be divided into detection zones. These zones should be influenced not by the physical installation of the fire alarm system but by compatibility with the emergency fire action plan. The existence of fire compartments should be considered and it may be that detection zones extending no further than a single fire compartment are appropriate.
214. Where the fire alarm system is zoned, a schematic plan showing the fire detection zones in a simple and unambiguous way should be displayed adjacent to the control panel to allow the source of a fire alarm actuation to be quickly identified. Even in the case where an addressable system is installed, zone indication is also likely to be an essential feature (an addressable fire alarm system is one where individual detectors and call points can be identified at the control and indicating equipment).
215. If a sprinkler system or other automatic life safety fire suppression system is installed in the building, this should be interlinked so that actuation of the suppression system in response to a fire should also cause operation of the fire alarm system.
216. Operation of the fire alarm system should cause the following:
217. With remote monitoring, the actuation of the fire alarm will cause a signal to be transmitted automatically to a remote alarm receiving centre (ARC); on receipt of a signal, the ARC would then call the Fire and Rescue Service. Even where there is monitoring by a remote alarm receiving centre, a back-up 999 call should also be made to the Fire and Rescue Service.
218. False alarms from automatic fire detection systems are a major problem which cause disruption to the running of premises and result in many unwanted calls to the Fire and Rescue Service. If there are frequent false alarms in the premises, people may become complacent and may not respond correctly to a warning in the event of a real fire. False alarms should not be seen as inevitable: each one should be investigated and the cause identified. Where remedial action is required to prevent a recurrence, such as changing a detector head or re-siting a call point, then this should be implemented. A fire alarm system should never be disabled by staff; if it is posing a problem then specialist help should be sought.
219. Information on maintenance and testing of fire alarm systems is contained in Chapter 5.
220. Technical Annexe 13.12 contains further information and benchmarks for fire alarm systems against which existing provision can be compared.