For the purpose of this part of BS 5839, the terms and definitions in BS EN ISO 13943 and the following apply.

3.1 addressable system: system in which signals from detectors, manual call points or any other devices are individually identified at the control and indicating equipment

3.2 alarm receiving center: ARC continuously manned premises, remote from those in which the fire detection and fire alarm system is fitted, where the information concerning the state of the fire alarm system is displayed and/or recorded, so that the fire and rescue service can be summoned

2) This replaces the previously referenced standard BS EN 50086.

3) These replace the previously referenced standard BS EN 50281.

3.3 alarm zone: geographical subdivision of the protected premises, in which the fire alarm warning can be given separately, and independently, of a fire alarm warning in any other alarm zone

3.4 aspirating smoke detection system: smoke detection system in which a sample of the atmosphere in the protected space is drawn by a fan or pump into a detector which may be remote from the protected space

3.5 audibility: property of a sound which allows it to be heard among other sounds

NOTE Audibility depends upon the relative loudness and frequency content of the sound in comparison with other sounds which are present at the same time.

3.6 automatic fire detection and fire alarm system: system (other than a single self-contained smoke or fire alarm) in which an alarm of fire can be initiated automatically

3.7 circuit: assembly of fire alarm components supplied from the same control equipment and protected against over current by the same protective device(s) or current limitation arrangements

3.8 circulation area: area (including a stairway) used mainly as a means of access between a room and an exit from the building or compartment

3.9 coincidence: arrangement designed so that an output is obtained only when at least two independent input triggering signals are present at the same time

NOTE This is not to be mistaken for “double knock”, which is a colloquial term often used for an arrangement whereby an output is given only when two successive signals are received from the same device.

3.10 combustion gas detector: automatic fire detector sensitive to gaseous products of combustion and/or thermal decomposition

3.11 commissioning: process by which it is determined that the installed system meets the defined requirements

3.12 competent person: person with the relevant current training and experience, and with access to the requisite tools, equipment and information, and capable of carrying out a defined task

3.13 control and indicating equipment: CIE component or components of a fire detection and fire alarm system through which other components can be supplied with power and which:

a) are used:

1) to receive signals from the connected detectors, manual call points or any other devices (e.g. input/output units);

2) to determine whether these signals correspond to a fire alarm condition;

3) to indicate any such fire alarm condition audibly and visually;

4) to indicate the location of the danger; and

5) possibly to record any of this information;

b) are used to monitor the correct functioning of the system and give audible and visible warning of any faults (e.g. short circuit, open circuit or fault in the power supply);

c) if necessary, are able to pass on the fire alarms signal:

1) to audible or visible fire alarm devices or to a voice alarm system;

2) to the fire alarm routing function to a fire ARC;

3) to the control function for fire protection equipment or systems; and

4) to other systems or equipment, such as a mimic panel.

3.14 critical signal path components and interconnections between every fire alarm initiation point (manual call point or automatic fire detector) and the input terminals on, or within, each fire alarm device and (where provided) transmission equipment within the premises for routing of signals to an ARC

3.15 designer: person or organization taking responsibility for design considerations

3.16 detection zone: subdivision of the protected premises such that the occurrence of a fire within it is indicated by a fire detection and fire alarm system separately from an indication of fire in any other subdivision

NOTE A detection zone usually consists of an area protected by several manual call points and/or detectors, and is separately indicated to assist in location of the fire, evacuation of the building and fire fighting.

3.17 detector: part of an automatic fire detection and fire alarm system that contains at least one sensor which constantly, or at frequent intervals, monitors at least one suitable physical and/or chemical phenomenon associated with fire, and that provides at least one corresponding signal to the CIE

NOTE The decision to give the alarm of fire or to operate automatic fire protection equipment might be made at the detector or another part of the system, for example at the CIE.

3.18 dual path alarm transmission system: alarm transmission system consisting of one primary alarm transmission system and one secondary alarm transmission system using diverse technology

3.19 false alarm: fire signal resulting from a cause(s) other than fire

NOTE False alarms can be subdivided into four categories:

a) unwanted alarms, in which a system has responded, either as designed or as the technology might reasonably be expected to respond, to any of the following:

1) a fire-like phenomenon or environmental influence (e.g. smoke from a nearby bonfire, dust or insects, processes that produce smoke or flame, or environmental effects that can render certain types of detector unstable, such as rapid air flow);

2) accidental damage;

3) inappropriate human action (e.g. operation of a system for test or maintenance purposes without prior warning to building occupants and/or an ARC);

b) equipment false alarms, in which a false alarm has resulted from a fault in the system;

c) malicious false alarms, in which a person operates a manual call point or causes a fire detector to initiate a fire signal, whilst knowing that there is no fire;

d) false alarms with good intent, in which a person operates a manual call point or otherwise initiates a fire signal in the belief that there is a fire, when no fire actually exists.

3.20 fire alarm device: component of a fire detection and fire alarm system, not incorporated in the CIE, which is used to give a warning of fire

NOTE For example, a sounder or visual alarm device.

3.21 fire alarm sounder: audible fire alarm device

3.22 fire engineering solution: application of science and engineering to the achievement of one or more fire safety objectives in such a way that the objectives are achieved without following, in full, prescriptive recommendations of a recognized code of practice.

3.23 fire hazard level: likelihood of fire occurring

3.24 fire-resisting construction: construction that is able to satisfy for a stated period of time some or all of the appropriate criteria given in the relevant parts of BS 476 (or equivalent International Standards)

3.25 fire risk: combination of the probability of fire occurring and the magnitude of the consequences of fire

3.26 fire signal: signal intended to indicate the occurrence of a fire

3.27 flame detector: automatic fire detector which responds to the radiation emitted by the flames from a fire

3.28 heat detector: automatic fire detector which responds to an increase in temperature

3.29 installation: work of fixing and interconnecting the components and elements of a system

NOTE Installation may be carried out by one or more parties.

3.30 installer: person or organization having responsibility for all or part of the process of installation

3.31 lantern-light: construction standing above the surface of a roof and intended to admit light to the space below

3.32 line detector: detector which responds to the phenomenon sensed in the vicinity of a continuous line

3.33 low fire risk area or room: area or room containing little or no combustible material and no ignition sources, in which any foreseeable fire is unlikely to spread such as to present any significant threat to escape by occupants or damage to property

NOTE Examples of combustible materials are furniture, fittings, storage or linings.

3.34 maintenance: work of inspection, servicing and repair necessary in order to maintain the efficient operation of the installed system

3.35 manual call point: component of a fire detection and fire alarm system which is used for the manual initiation of an alarm

3.36 manual system: system containing no automatic detectors and in which an alarm of fire can only be initiated manually

3.37 maximum alarm load: maximum load imposed on a fire alarm system power supply under fire conditions, comprising the power required for simultaneous operation of all fire alarm devices, fire signals from all automatic fire detectors and manual call points in the building, any power drawn by other systems and equipment in the alarm condition and any power required for transmission of fire signals to an ARC (if a facility for this is provided)

3.38 mimic diagram: topographic representation of the protected premises and their subdivisions, using light-emitting indicators for each subdivision such that the indications of the fire detection and fire alarm system can be rapidly related to the layout of the premises

3.39 minimum static response temperature: minimum temperature at which a heat detector would produce a fire alarm signal if subjected to a very small rate of rise of temperature

3.40 multi-sensor fire detector: fire detector that monitors more than one physical and/or chemical phenomenon associated with fire

3.41 networked system fire detection and fire alarm system in which several items of CIE are interconnected and able to exchange information

3.42 normal supply: supply from which the fire detection and fire alarm system is expected to obtain its power under normal conditions

NOTE The normal supply is usually derived from the public electricity supply system.

3.43 phased evacuation: system of evacuation in which different parts of the premises are evacuated in a controlled sequence of phases, those parts of the premises expected to be at greatest risk being evacuated first

NOTE A phased evacuation normally requires at least a two-stage alarm system.

3.44 point detector: detector which responds to a phenomenon sensed in the vicinity of a fixed point

3.45 pre-alarm warning: early warning of conditions which might (or might not) represent a fire, but indicates an approaching alarm condition

3.46 premises management: persons having day-to-day control of the premises, the fire detection and fire alarm system(s) and implementation of the fire procedures

NOTE In large premises, a single person with specialist knowledge is often delegated the responsibility for the fire detection and fire alarm system and associated matters. In small premises, a person with specialist knowledge is unlikely to be present, but responsibility for the fire detection and fire alarm system can still be delegated to a specific person.

3.47 protection: presence of one or more automatic fire detector(s) able to initiate actions needed for the safety of life or property in the event of a fire

3.48 purchaser: person or organization taking primary responsibility for acceptance of and payment for the installed system

3.49 radio-linked system: fire detection and fire alarm system in which some or all of the interconnections between components are made by radio links

3.50 rate of rise heat detector: automatic fire detector which initiates an alarm when the rate of change of the measured phenomenon with time exceeds a certain value, for a sufficient time

NOTE For each class in BS EN 54-5, there are two subclasses: R and S. So-called rate of rise heat detectors may be taken to correspond to R, and fixed temperature detectors to S.

3.51 repair: non-routine work necessary to restore the efficient operation of the installed system

3.52 search distance: distance which has to be traveled by a searcher within a zone in order to determine visually the position of a fire

NOTE The distance is not measured between the point of entry of the zone and the location of the fire, but only between the point of entry and the location at which a person searching for the fire would first become aware of the location of the fire.

3.53 sector: subdivision of the protected premises normally containing several zones

NOTE A sector can cover more than one building.

3.54 servicing: routine process of work on the system (including cleaning, realignment, adjustment and replacement) carried out at predetermined intervals

3.55 short circuit isolators: device, which can be connected into a transmission path of a fire detection and fire alarm system, to limit the consequences of low parallel resistance faults between the lines of this transmission path

NOTE A short circuit isolating device can be a physically separate device or it can be incorporated into another device (e.g. integrated into a smoke detector or detector base).

3.56 smoke: particulate and aerosol products of combustion generated by a fire, whether this be of the smoldering or open flame type

NOTE In general, the particle diameters range from 1 nm (invisible smoke) to 10 μm (visible smoke).

3.57 smoke detector: automatic fire detector sensitive to particulate products of combustion and/or pyrolysis suspended in the atmosphere (aerosols)

3.58 soak period: period after a fire detection and fire alarm system has been commissioned, but prior to handover, during which the system’s performance in relation to false alarms and faults is monitored

3.59 staff alarm: restricted alarm, following the operation of a manual call point or automatic fire detector, given to certain staff in the premises to permit investigation prior to evacuation and/or summoning of the fire and rescue service

NOTE The use of staff alarms in response to signals from manual call points is not generally acceptable (see 19.2.2).

3.60 staged fire alarm: arrangement in which two or more stages of alarm can be given within a given area

NOTE 1 Examples of staged alarm systems are a two-stage system capable of giving “alert” or “evacuate” signals, or a three-stage alarm system capable of giving “staff alarm”, “alert” or “evacuate” signals.

NOTE 2 The normal condition, under which no alarm is given, is not counted as a stage of alarm.

NOTE 3 In this standard, in order to avoid confusion:

a) the term “stage” is used to describe the different stages of alarm in part, or all, of the premises;

b) the term “phase” is used in describing the sequence of phases of evacuation from different areas of the premises.

NOTE 4 A pre-alarm warning (see 3.45) is not a stage of alarm.

3.61 standby supply electricity supply, commonly from a rechargeable battery, which is automatically connected to the fire alarm system when the normal supply fails

3.62 time-related system system in which the response or sensitivity of automatic fire detectors is changed with the time of day

3.63 unwanted fire alarm signal UFAS false alarm from an automatic fire detection and fire alarm system that has been passed on to the fire and rescue service

3.64 user person or organization having control of the building (or part of the building) in which the fire detection and fire alarm system is installed

3.65 visual alarm device device which generates a flashing light to signal to the occupants of a building that a fire condition exists[SOURCE: BS EN 54-23:2010, 3.1.10]

3.66 voice alarm system sound distribution system that provides means for automatically broadcasting speech messages and warning signals

NOTE Voice alarm systems commonly include a facility for transmission of live voice messages, as well as automatically generated messages.

3.67 Voice sounder: fire alarm sounder that contains the components necessary to generate and broadcast digitally recorded speech messages

3.68 zone plan: diagrammatic representation of a building, showing specific topographic information and the division of the building into detection zones.

3 Terms and definitions