NFPA 72 currently recognized four methods of communication from the protected premises to the supervising station for fire alarm systems: Performance-Based Technology, Digital Alarm Communicator Systems, Two-Way Radio Frequency (RF) Multiplex, and One-Way Private Radio Alarm Systems.
Performance-based technology is the most recent entry into fire alarm communications options, and has rapidly become the most popular. Performance-based technology provides a set of operating parameters and requirements for communications technology, allowing for any current or new technologies that meet the requirements and are listed for the application to be used in fire alarm system communications. Currently, performance-based technology encompasses IP and cellular communicators.
One of the driving forces of the acceptance of performance-based technologies such as IP and cellular is the provisions in NFPA 72 that allow these to be used as a single communications path technology. NFPA 72 requires that the single pathway have 60 minute supervision (5 minute supervision was required in 72-2010).
Digital Alarm Communicator System
A digital alarm communicator system utilizes a DACT (digital alarm communicator transmitters) connected to a telephone line to send signals over the telephone network to the supervising station. Prior to NFPA 72-2013, DACTs were permitted to be connected to two telephone lines.
However, the 2013 edition of NFPA 72 started to require that DACTs be connected to one telephone line, with the second pathway being another technology (performance-based, one-way radio, or two-way radio). Additionally, pre-2013 DACTs were permitted to send test signals every 24 hours. As of 2013, the requirement was reduced to 6 hours.
Two-Way Radio Frequency (RF) Multiplex
Two-way radio frequency (RF) multiplex, commonly called two-way radio, provide two-way wireless supervision from the protected premises to the supervising station. Because the communication is periodically polled to test the communications path, the protected premises radio is only required to communicate with a single remote device.
One-Way Private Radio Alarm System
One-way private radio alarm systems, commonly called one-way radio, provide one-way communication from the protected premises to the supervising station. Because the communication path is tested every 24 hours, the protected premises radio is required to communicate with two separate remote radio devices.
The requirements for these technologies are spelled out in NFPA 72, Chapter 26. A table is provided in Annex A (Table A.26.6.1) provides a handy comparison of the requirements for each of the technologies.