Fire Alarm Systems (FAS) are an effective and secure way of automatic, non-accidental detection, which decreases the time for detection and fire extinguishing. The final result from the use of FAS is that the losses are considerably decreased and the possibility of injuries to people is reduced. FAS is an automatic system which purpose is to detect fire in its initial phase of developing, to produce an alarm signal for evacuation of the people who are currently at the site, to send fire alarms and a warning to a remote centre and to activate the fire fighting system and other protection devices/systems. The first two functions of the system are mandatory, and the latter two functions are optional.