Fire Alarm Communications Technologies
NFPA 72 recognizes four communications technologies: performance based, digital alarm communicator, one-way radio, and two-way radio systems. Each of these technologies has specific performance requirements and encompasses different types of equipment.
Performance based technologies are technologies that are not specifically identified in NFPA 72 but meet the performance requirements of the Code. The most common performance based technologies are IP and cellular. IP communicators use the premises internet connection as a communications pathway, while cellular communicators use cellular networks as a communications pathway.
Digital alarm communicator systems use the public switched telephone network (PSTN) as a communication pathway. DACTs (digital alarm communicator transmitter) are a common feature on fire alarm control panel since telephone service is available pretty much everywhere.
DACTs requirements underwent a significant change in the 2013 edition of NFPA 72. Prior to the 2013 edition, DACTs were permitted to be connected to two separate telephone lines and send test signals every 24 hours. In the 2013 edition of NFPA 72, requirements were changed to require the use of one telephone line and then another technology instead of a second telephone line. The second technology could be performance based (IP or cellular), one-way or two-way radio. NFPA 72, 2013 edition also increased the test interval from 24 hours to 6 hours.
Radio systems are classified as one-way and two-way. One way radio systems only transmit signals from the premises and are required to be able to connect with at least two repeaters or receivers. Two-way radio systems have bi-directional communication from the premises to the receiver.
NFPA 72 permits performance based technologies to use single or multiple communications paths from the protected premises to the supervising station. A single communications path requires 60 minute supervision of the pathway with indication of the failure at the supervising station and protected premises. The 2010 edition of NFPA 72 required this supervision to be 5 minutes. Single communications path allows for performance based technologies like IP or cellular to be used as the sole method of communication, with AHJ approval.
Single Communications Path
Multiple Communications Path
Performance based technologies may also use multiple communication paths. When multiple communications paths are used each pathway be supervised every 6 hours. Some manufacturers offer performance based technology products that utilize both IP and cellular to provide multiple communications path performance. This provides redundancy of communications paths and reduced the supervision requirement.