Fire alarm system

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A fire alarm notification appliance widely used in the United States and Canada, pictured is a Wheelock MT-24-LSM. Wheelock mt2.jpg
A fire alarm notification appliance widely used in the United States and Canada, pictured is a Wheelock MT-24-LSM.

A fire alarm system has a number of devices working together to detect and warn people through visual and audio appliances when smoke, fire, carbon monoxide or other emergencies are present. These alarms may be activated automatically from smoke detectors, and heat detectors or may also be activated via manual fire alarm activation devices such as manual call points or pull stations. Alarms can be either motorized bells or wall mountable sounders or horns. They can also be speaker strobes which sound an alarm, followed by a voice evacuation message which warns people inside the building not to use the elevators. Fire alarm sounders can be set to certain frequencies and different tones including low, medium and high, depending on the country and manufacturer of the device. Most fire alarm systems in Europe sound like a siren with alternating frequencies. Fire alarm electronic devices are known as horns in the United States and Canada, and can be either continuous or set to different codes. Fire alarm warning devices can also be set to different volume levels.



After the fire protection are established – usually by referencing the minimum levels of protection mandated by the appropriate model building code, insurance agencies, and other authorities – the fire alarm designer undertakes to detail specific components, arrangements, and interfaces necessary to accomplish these goals. Equipment specifically manufactured for these purposes is selected and standardized installation methods are anticipated during the design.

Last version 2019; Status, Published. This code is part of a family standard NFPA

There are national codes in each European country for planning, design, installation, commissioning, use and maintenance of fire detection system with additional requirements that are mentioned on TS 54 -14


A fire alarm control panel Honeywellfirepanel.JPG
A fire alarm control panel
Fire Alarm Speaker and switch Fire Alarm Systems 4.jpg
Fire Alarm Speaker and switch

Initiating devices

Fire alarm switch Fire alarm001.jpg
Fire alarm switch

Notification appliances

A speaker and a remote light Honeywellspeakerv33.JPG
A speaker and a remote light

As per NFPA 72, 18.4.2 (2010 Edition)Temporal Code 3 is the standard audible notification in a modern system. It consists of a repeated 3-pulse cycle (.5s on .5s off .5s on .5s off .5s on 1.5s off). Voice Evacuation is the second most common audible in a modern system. Legacy systems, typically found in older schools and buildings have used continuous tones alongside other audible schemas.

Emergency voice alarm communication systems

Mass notification systems/emergency communication systems

Mass notification systems often extend the notification appliances of a standard fire alarm system to include PC based workstations, text-based digital signage, and a variety of remote notification options including email, text message, RSS feed , or IVR-based telephone text-to-speech messaging.

Building safety interfaces

Coded fire alarm pull station below a 10" bell. Couchpull.JPG
Coded fire alarm pull station below a 10" bell.

European fire alarm system categories

Fire alarm systems in non-domestic premises are generally designed and installed in accordance with the guidance given in BS 5839 Part 1. There are many types of fire alarm systems each suited to different building types and applications. A fire alarm system can vary dramatically in both price and complexity, from a single panel with a detector and sounder in a small commercial property to an addressable fire alarm system in a multi-occupancy building.

BS 5839 Part 1 categorizes fire alarm systems as: [9]

Categories for automatic systems are further subdivided into L1 to L5 and P1 to P2.

MManual systems, e.g. handbells, gongs, etc. These may be purely manual or manual electric, the latter may have call points and sounders. They rely on the occupants of the building discovering the fire and acting to warn others by operating the system. Such systems form the basic requirement for places of employment with no sleeping risk.
P1The system is installed throughout the building – the objective is to call the fire brigade as early as possible to ensure that any damage caused by the fire is minimized. Small low-risk areas can be excepted such as toilets and cupboards less than 1m².
P2Detection should be provided in parts of the building where the risk of ignition is high and/or the contents are particularly valuable. Category 2 systems provide fire detection in specified parts of the building where there is either high risk or where business disruption must be minimized.
L1A category L1 system is designed for the protection of life and which has automatic detectors installed throughout all areas of the building (including roof spaces and voids) with the aim of providing the earliest possible warning. A category L1 system is likely to be appropriate for the majority of residential care premises. In practice, detectors should be placed in nearly all spaces and voids. With category 1 systems, the whole of a building is covered apart from minor exceptions.
L2A category L2 system designed for the protection of life and which has automatic detectors installed in escape routes, rooms adjoining escape routes and high hazard rooms. In medium-sized premises (sleeping no more than ten residents), a category L2 system is ideal. These fire alarm systems are identical to an L3 system but with additional detection in an area where there is a high chance of ignition (e.g., kitchen) or where the risk to people is particularly increased (e.g., sleeping risk).
L3This category is designed to give early warnings to everyone. Detectors should be placed in all escape routes and all rooms that open onto escape routes. Category 3 systems provide more extensive cover than category 4. The objective is to warn the occupants of the building early enough to ensure that all are able to exit the building before escape routes become impassable.
L4Category 4 systems cover escape routes and circulation areas only. Therefore, detectors will be placed in escape routes, although this may not be suitable depending on the risk assessment or if the size and complexity of a building are increased. Detectors might be sited in other areas of the building, but the objective is to protect the escape route.
L5This is the "all other situations" category, e.g., computer rooms, which may be protected with an extinguishing system triggered by automatic detection. Category 5 systems are the "custom" category and relate to some special requirements that cannot be covered by any other category.


An important consideration when designing fire alarms is that of individual zones. The following recommendations are found in BS 5839 Part 1:

Also, the NFPA recommends placing a list for reference near the FACP showing the devices contained in each zone.

See also

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Alarm device Type of signal (or device) that alerts people to a dangerous condition

An alarm device or system of alarm devices gives an audible, visual or other form of alarm signal about a problem or condition. Alarm devices are often outfitted with a siren.

Fire sprinkler system sprinkler

A fire sprinkler system is an active fire protection method, consisting of a water supply system, providing adequate pressure and flowrate to a water distribution piping system, onto which fire sprinklers are connected. Although historically only used in factories and large commercial buildings, systems for homes and small buildings are now available at a cost-effective price. Fire sprinkler systems are extensively used worldwide, with over 40 million sprinkler heads fitted each year. In buildings completely protected by fire sprinkler systems, over 96% of fires were controlled by fire sprinklers alone.

Smoke detector Device that detects smoke, typically as an indicator of fire

A smoke detector is a device that senses smoke, typically as an indicator of fire. Commercial security devices issue a signal to a fire alarm control panel as part of a fire alarm system, while household smoke detectors, also known as smoke alarms, generally issue a local audible or visual alarm from the detector itself or several detectors if there are multiple smoke detectors interlinked.

Fire alarm notification appliance A device to alert the user in a condition such as a fire

A fire alarm notification appliance is an active fire protection component of a fire alarm system. A notification appliance may use audible, visible, or other stimuli to alert the occupants of a fire or other emergency condition requiring action. Audible appliances have been in use longer than any other method of notification. Initially, all appliances were either electromechanical horns or electric bells, which would later be replaced by electronic sounders. Most of today's appliances produce sound pressure levels between 45 and 120 decibels at ten feet.

Fire safety Practices intended to reduce the destruction caused by fire

Fire safety is the set of practices intended to reduce the destruction caused by fire. Fire safety measures include those that are intended to prevent ignition of an uncontrolled fire, and those that are used to limit the development and effects of a fire after it starts.

PASS device Device used to set off an alarm when a firefighter is in distress

A PASS device also known as a distress signal unit (DSU) or ADSU, is a personal safety device used primarily by firefighters entering a hazardous (IDLH) environment such as a burning building. The PASS device sounds a loud (95 decibel) audible alert to notify others in the area that the firefighter is in distress. On a fireground, the sound of an activated PASS device indicates a true emergency and results in an immediate response to rescue the firefighter(s) in distress. In the United States, the National Fire Protection Association sets standards for PASS devices in NFPA 1982.

Security alarm A system that detects unauthorised entry

A security alarm is a system designed to detect intrusion – unauthorized entry – into a building or other area such as a home or school. Security alarms are used in residential, commercial, industrial, and military properties for protection against burglary (theft) or property damage, as well as personal protection against intruders. Security alarms in residential areas show a correlation with decreased theft. Car alarms likewise help protect vehicles and their contents. Prisons also use security systems for control of inmates.

Fire alarm control panel

A fire alarm control panel (FACP), fire alarm control unit (FACU), or simply fire alarm panel is the controlling component of a fire alarm system. The panel receives information from devices designed to detect and report fires, monitors their operational integrity and provides for automatic control of equipment, and transmission of information necessary to prepare the facility for fire based on a predetermined sequence. The panel may also supply electrical energy to operate any associated initiating device, notification appliance, control, transmitter, or relay. There are four basic types of panels: coded panels, conventional panels, addressable panels, and multiplex systems.

This is a glossary of firefighting equipment.

Gaseous fire suppression use of inert gases and chemical agents to extinguish a fire

Gaseous fire suppression, also called clean agent fire suppression, is a term to describe the use of inert gases and chemical agents to extinguish a fire. These agents are governed by the National Fire Protection Association (NFPA) Standard for Clean Agent Fire Extinguishing Systems – NFPA 2001 in the US, with different standards and regulations elsewhere. The system typically consists of the agent, agent storage containers, agent release valves, fire detectors, fire detection system, agent delivery piping, and agent dispersion nozzles. Less typically, the agent may be delivered by means of solid propellant gas generators that produce either inert or chemically active gas.

SimplexGrinnell, a subsidiary of Tyco International, is an American company specializing in active fire protection systems, communication systems and testing, inspection and maintenance services. The company headquarters is in Boca Raton, Florida; corporate sales and marketing offices are in Westminster, Massachusetts, and the company has about 160 district offices throughout North America. It is currently the largest fire protection company in the world.

Manual fire alarm activation fire

Manual fire alarm activation is typically achieved through the use of a pull station or call point, which then sounds the evacuation alarm for the relevant building or zone. Manual fire alarm activation requires human intervention, as distinct from automatic fire alarm activation such as that provided through the use of heat detectors and smoke detectors. It is, however, possible for call points/pull stations to be used in conjunction with automatic detection as part of an overall fire detection and alarm system. Systems in completed buildings tend to be wired in and to include a control panel. Systems for use during construction can also be wireless or mechanical, however it is recommended by the Structural Timber Association in the UK that for timber-framed constructions, interconnecting wireless systems be used.

Carbon monoxide detector A device that measures carbon monoxide (CO)

A carbon monoxide detector or CO detector is a device that detects the presence of the carbon monoxide (CO) gas to prevent carbon monoxide poisoning. In the late 1990s Underwriters Laboratories changed the definition of a single station CO detector with a sound device to carbon monoxide (CO) alarm. This applies to all CO safety alarms that meet UL 2034 standard; however for passive indicators and system devices that meet UL 2075, UL refers to these as carbon monoxide detectors.


Notifier or Notifier by Honeywell is a manufacturer of engineered fire alarm systems with over 500 distributors worldwide, and regional support operations on every continent. Notifier is headquartered in Northford, Connecticut, United States, and is a division of the Honeywell Life Safety Group.

Fire protection all measures, that prevent or avoid the occurrence of a fire or the spread of fire

Fire protection is the study and practice of mitigating the unwanted effects of potentially destructive fires. It involves the study of the behaviour, compartmentalisation, suppression and investigation of fire and its related emergencies, as well as the research and development, production, testing and application of mitigating systems. In structures, be they land-based, offshore or even ships, the owners and operators are responsible to maintain their facilities in accordance with a design-basis that is rooted in laws, including the local building code and fire code, which are enforced by the Authority Having Jurisdiction.

Active fire protection (AFP) is an integral part of fire protection. AFP is characterized by items and/or systems, which require a certain amount of motion and response in order to work, contrary to passive fire protection.

The NFPA 72 is a standard published by the National Fire Protection Association every 3 years for installations in the United States.

Faraday is a Florham Park, New Jersey company that specializes in fire protection systems.

Optical beam smoke detector

An optical beam smoke detector is a device that uses a projected beam of light to detect smoke across large areas, typically as an indicator of fire. They are used to detect fires in buildings where standard point smoke detectors would either be uneconomical or restricted for use by the height of the building. Optical beam smoke detectors are often installed in warehouses as a cost-effective means of protecting large open spaces.

BS 5839 Part 1Fire detection and fire alarm systems for buildings – Part 1: Code of practice for design, installation, commissioning and maintenance of systems in non-domestic premises is a standard published by the British Standards Institution. BS 5839-1:2013 supersedes BS 5839-1:2002+A2:2008, which has been withdrawn.


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