Incoming Transmission: Fire Alarm Communication Methods

By Thomas P. Hammerberg | Mar 15, 2019
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Some of the greatest changes in NFPA 72 over the last couple of code cycles have been the changes in ways to transmit signals from the fire alarm control unit to the monitoring facility. I’d like to take this opportunity to review some of these changes.

In the 2013 code cycle, the International Association of Fire Chiefs proposed a number of potential changes with the intent of reducing the effects of unwanted alarms. Virtually none passed, but that is another story. One change requested was to allow only addressable systems to be installed so the system would report alarms individually as they come in and store signal history in the event buffer. By providing this information, it was felt unwanted alarms could be better identified and therefore reduced.

That proposal was not accepted as presented, but a modified version was accepted. NFPA 72 now states fire alarm signals identified by events, individual points or zones at the supervising station must be retransmitted to the fire department communications center by the same methods. In addition, the fire department requires fire alarm signals transmitted to the supervising station must be either point or zone identified. I recommend you always check with the fire department to determine the requirements prior to installation.

Also beginning in 2013, there was a requirement to have all fire alarm signals verified prior to dispatching. Originally, the monitoring company personnel were required to “preverify” by calling the fire department when a signal was received and was being verified. That was dropped in 2016 because it was confusing and redundant. The language has been modified to now require verification when all of eight different requirements are met (see 26.2.2), including being required by the fire department, the fire department provides notification in writing of this requirement, the verification doesn’t take longer than 90 seconds and is performed only by predetermined authorized personnel on-site. True and inconclusive alarms will be dispatched immediately. Verified unwanted alarms are communicated as directed by the fire department.

In 2019, carbon-monoxide (CO) detection requirements were moved from NFPA 720 to NFPA 72, so there are new requirements for transmitting CO signals. These signals take precedence over supervisory or trouble signals and must be clearly indicated as CO alarm signals. The supervising station personnel must perform a number of actions upon receipt of a CO alarm signal. If you monitor CO systems, review Chapter 26,

If you install Central Station Service Alarm Systems, you should be aware of a new requirement for reporting trouble signals that do not restore within 15 minutes to the subscriber. I believe the intent of this change is to allow not reporting trouble signals due to power outages.

Most monitored fire alarm systems are considered Remote Station Fire Alarm Systems, described in 26.5 of NFPA 72. Over the last couple of code cycles, the committee for this chapter has made a few changes regarding notification to the fire department concerning who will be performing tests and inspections as well as their qualifications. If you monitor fire alarms, it is a good idea to review the requirements when new code editions are adopted. These changes are intended to provide additional requirements to better insure fire alarm systems will be tested and maintained by qualified personnel. At one point, there were no requirements to transmit remote station system trouble signals to the supervising station. Now, you must transmit trouble signals, but they are not required to go to the same location as the alarm and supervisory signals. This means trouble signals can be sent to any approved location with personnel training to take action to correct the trouble signal instead of to the supervising station.

You will notice in the 2019 edition that the term “public switched telephone network (PSTN)” has been updated to “managed facilities-based voice network (MFVN)” to be more in line with today’s technology. Although digital alarm communicator transmitters (DACTs) can still be installed, the requirements have been changed to make this unfeasible. The main reason is that DACTs originally were to be connected to copper telephone lines powered from the telephone central office.

PSTNs are no longer being installed with copper, and, if installed at all, typically are fiber optic cables. These cables require power and any available secondary power is provided at the street pedestals and will typically not exceed 8 hours. DACTs must now send test signals every 6 hours instead of every 24 hours. You can no longer use two telephone lines. You must use one telephone line for the primary circuit and the second circuit must be some other technology; any of which can be used as a sole communications path. We have covered this before, but it is a good idea to review the Performance-Based Technologies section in 26.6, including a new section on wireless mesh networks.

About The Author

HAMMERBERG, SET, CFPS, is an independent fire alarm presenter and consultant in The Villages, Fla. He can be reached at [email protected]

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