Fire alarm system

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Schematic representation of a BMA

A fire alarm system ( BMA ) is a hazard alarm system from the field of preventive fire protection that receives events from various fire alarms , evaluates them and then reacts. In response, various technical devices can be activated, e.g. B .:

Fire detectors with different parameters (e.g. smoke, temperature, flames etc.) are used to detect (fire) events. A fire extinguishing system can also be used to detect a fire (bursting of a sprinkler barrel).

Mostly fire alarm systems are installed in particularly endangered buildings, such as airports, train stations, universities, schools, company buildings, factories, retirement homes or hospitals. The obligation to install a fire alarm system connected to the fire brigade is regulated in building regulations within the framework of special building regulations. If necessary, the building supervision can request the installation of a fire alarm system with the building permit . It can also be provided for insurance reasons to limit an insurance premium.

In Germany , the requirements of DIN 14675 are generally used for planning fire alarm systems required by building regulations . Systems required for insurance purposes must meet the requirements of VdS 2095. For the design and the components, specifications are made in DIN VDE 0833-2. The components themselves are defined in the DIN EN 54 series of standards (parts 1 to 31).

In many countries, apartments will have to be equipped with so-called smoke alarm devices in the future. In most of the German federal states, they are already mandatory, see smoke alarm device obligation . These smoke alarm devices (according to DIN 14676 ) are small fire alarm systems, consisting of a detecting and an alarming unit.

The advantage of the fire alarm system is that a fire is detected at an early stage regardless of the presence of people and measures can be initiated. In this way, the people alerted by the fire alarm system can intervene quickly and possibly extinguish fires as soon as they develop. In areas where people sleep (e.g. hotels), a fire alarm in connection with an alarm can be an essential element for personal protection. Basically, the possibility of false alarms must be taken into account. a. can be triggered by incorrect evaluations of the automatic fire alarms as well as malicious actuation of the manual call points (formerly push-button alarms). In the meantime, the development is so far that the risk of false alarms is greatly reduced with object-oriented specialist planning (e.g. operating mode TM).


A fire alarm panel with the usual
fire brigade route cards in Germany

As a rule, several fire detectors are combined into groups or loops. If an alarm is triggered, the fire alarm system displays the number and sometimes also the location of the fire alarm.

In systems with the latest technology, the participants are interconnected on a data bus in a ring so that if one side of the line fails, the system can recognize and evaluate the participants via the other side of the line.

For special areas of application ( e.g. clean rooms such as laboratories and technical rooms), smoke extraction systems (RAS) are used as an alternative to a small fire alarm system or as part of a large system . Here, air is fed to a central detector unit via a pipe system.

If hot work (e.g. welding work) is to be carried out, i. General the entire loop in question should be switched off, as hot work through the development of heat, light or smoke can cause a false alarm. The rest of the object remains monitored during this time. In newer systems it is possible to switch off individual detectors. False alarms (commonly: false alarms) arise, among other things, because hot work is not correctly entered in the fire alarm control panel. In addition, false alarms arise when there is z. B. bursting of the sprinkler pipe leads to a pressure drop in the sprinkler system .

Fire alarm center (BMZ)

The control unit of a BMZ
BMZ sign on a building

The fire alarm control panel (abbreviation: BMZ) is the control center and thus the most important part of the system. This is where all messages from the installed sensors appear and trigger the previously programmed actions. This can be the placing of an emergency call, the activation of a computer or an announcement unit. The BMZ usually combines a control unit and the so-called fire brigade control panel . If the control unit is installed separately, the control panel and other information are located in an easily accessible fire brigade information center .

After the BMA has been triggered, the incoming fire brigade can gain access to the property via the fire brigade key depot. In the building, the triggered detector (if available ) is detected with the help of the fire brigade display panel (FAT). The most important functions are operated via the fire brigade control panel. Optionally, the detector can also be identified via a fire alarm panel. In the case of a fire alarm panel, the floor plan of the building is shown, the individual detectors are identified by LEDs . The fire brigade now takes the fire brigade route cards from the routing card box , which show the fastest access for each individual detector group .

Depending on the location, size and location of the building, the fire brigade can also request a ticket printer when the BMA is set up. If necessary, this will print out the required route cards on site.

Connection principles

Transmission options

The alarm forwarding to the fire brigade , operations center or private security service usually takes place via a demand-controlled IP connection. If this connection fails, an alternative option is established redundantly in accordance with the standard. Nowadays, GSM is used regularly for this purpose .

In Germany , existing devices that communicate via ISDN are gradually being replaced, as the ISDN supply has been discontinued since 2018.

Connection conditions for fire alarm systems

The technical Aufschaltbedingungen for fire alarm systems (TAB; sometimes on switching condition), be in Germany by the individual counties or under the direction of the local fire department published. They define the individually specified technical connection conditions that are absolutely necessary in order to plan, install and maintain a fire alarm system in accordance with DIN 14675.

DIN 14675 , which has been in effect since November 2003 , stipulates that planning, project planning, assembly and commissioning as well as maintenance work are only carried out by companies or engineering offices that are certified in accordance with DIN 14675. This requirement has been adopted in most of the newly written TABs.

The transmission facility must be requested from the regional concessionaire. The end customer (operator / owner of the property) concludes a rental agreement with the concessionaire for a certain period (usually 10 years).

The fire alarm system is only accepted if the relevant TAB is complied with.

As a rule, the guidelines of the VdS must be met and important components of the fire alarm system must bear the VdS test mark.

Among other things, it is usually required, with the exception of toilets and washrooms, to equip all rooms (e.g. lounges, hallways, stairwells, attics and basement rooms) with a certain number of automatic fire alarms . In the stairwells, additional manual call points are to be provided on the ground floor . Red fire alarm cables are used for the wiring, similar to the usual telephone installation cables JY (ST) Y, but with wire diameters of 0.8 mm instead of 0.6 mm.

In Austria , the fire alarm system itself must comply with the current version of the technical guideline for preventive fire protection TRVB -123 S. The regulations for being allowed to switch on a fire alarm system at the fire brigade are contained in TRVB 114 S. In addition to the technical requirements, organizational measures are also necessary. A fire protection system is connected to a fire brigade key depot and a fire protection plan must be in place . Data transmission must always be possible via two redundant systems.

Avoidance of false alarms from automatic fire alarm systems

Automatic fire alarm systems are often installed voluntarily in commercial and industrial companies, but in the majority of cases to meet the legal requirements or the requirements of fire insurance . In most cases, direct forwarding of the alarm to the fire brigade is required. In order to achieve the protection goals of fire alarm systems - personal protection, property protection, neighborhood protection, environmental protection, etc. - it is necessary to inform the fire brigade as early as possible. In contrast to private residential properties, the fire brigade is not alerted by a telephone call, but by a fire brigade emergency call facility. On the basis of previously defined deployment plans, the fire brigade can locate the source of the fire as quickly as possible and carry out rescue and extinguishing work. In some cases it is possible to limit the fire to the place of the outbreak or at least to a part of the building before it affects the whole building.

In addition to the necessary and deliberate alerting of the fire brigade, false alarms are still common. If the fire brigade is automatically alerted by a fire alarm system without a real fire prevailing, one speaks of a false alarm . The problem of unwanted fire brigade alarms is a major challenge for the voluntarily organized fire brigades in particular.

False alarms are divided into maliciously caused alarms, false alarms and false alarms .


The protection class describes the monitoring with automatic fire detectors of a fire alarm system and is differentiated as follows:

  • Category 1: Full protection (entire building)
  • Category 2: partial protection (one or more fire compartments )
  • Category 3: Protection of escape and rescue routes
  • Category 4: Equipment protection (e.g. for property)

Manufacturer (selection)


  • Frieder Kircher, Rainer Sonntag: Die Roten Hefte, Issue 25 - Preventive Fire Protection . 1st edition. Kohlhammer, Stuttgart 2014, ISBN 978-3-17-016996-8 .

Web links

Wiktionary: Fire alarm system  - explanations of meanings, word origins, synonyms, translations
Commons : Fire alarm system  - album with pictures, videos and audio files

Individual evidence

  1. Fire alarm systems - Part 1: Construction and operation. In: Standard: DIN 14675-1. German Institute for Standardization , April 2018, accessed on November 13, 2019 .
  2. Fire alarm systems - Part 1: Introduction; German version EN 54-1: 2011. In: Standard: DIN EN 54-1. German Institute for Standardization, June 2011, accessed on November 13, 2019 .