Fire Sprinkler Monitoring & Supervision: NFPA 13 and NFPA 72

In most cases, the model fire codes used in the United States require new buildings to monitor sprinkler waterflow in accordance with NFPA 72. The International Fire Code (IFC), Section 903.4, requires valves controlling water supply for automatic sprinkler systems to be supervised by a listed fire alarm control unit. NFPA 1 and NFPA 101 contain similar requirements. But what does it mean to be electrically supervised in accordance with NFPA 72?

What does electrically supervised mean?

Electrically supervised means, a listed fire alarm control unit is provided at the protected premises to supervise the water supply valves controlling the automatic sprinkler system. NFPA 72 refers to this as a dedicated function fire alarm system. NFPA 72 added “dedicated function fire alarm system” to the definitions several cycles back to clarify there are conditions when a fire panel is necessary to monitor a specific function (sprinkler control valves, duct detectors, elevator detection, etc.), but a full fire alarm system may not be required. A dedicated function fire alarm system is not required to have notification appliances, common area detection, or pull stations because the system is “dedicated” to a specific function. In this case, monitoring sprinkler waterflow.

NFPA 13 outlines four conditions for supervision of sprinkler control valves in the 2022 Edition of NFPA 13, Section The four conditions are:

  1. Central station, proprietary, or remote station signaling service
  2. Local signaling service that will cause the sounding of an audible signal at a constantly attended point.
  3. Valves locked in the correct position
  4. Valves located within fenced enclosures under the control of the owner, sealed in the open position, and inspected weekly as part of an approved procedure.

IFC Section 102.7.2 takes it a step further where it says, when a referenced standard includes subject matter that is within the scope of this code (IFC), the provisions of the IFC shall take precedence over the provisions in the referenced standard. In this case, IFC section 903.4 requiring a listed fire alarm control unit takes precedence over NFPA 13 (conditions 2, 3 and 4) supervision requirements.

NFPA 13 and NFPA 72

Now that we know sprinkler control valves need to be monitored by a listed fire alarm control unit, what requirements apply to sending the signal from the protected premises to the supervising station? Due to the complexity of this question (and the topic in general), this blog will be broken up into a series, and each article will address different criteria related to monitoring of automatic sprinkler and fire alarm systems. Chapter 26 – Supervising Station Alarm Systems in NFPA 72 addresses how to send the sprinkler waterflow and fire alarm signal to the supervising station.

Single or Multiple Communication Path?

One of the first criteria in determining the method of fire sprinkler system monitoring is for the owner and contractor to determine if they want a single communication path or a multiple communication path. Both have different requirements in NFPA 72 and there are pros and cons to each. As the term implies, a single communication path refers to one transmission technology. Multiple communication paths use more than one transmission technology to send the signal. Single communication technologies can be less expensive when the owner considers monthly recurring charges. Multiple communication technologies require the owner to pay for two phone lines, which the owner may feel is unnecessary. On the other hand, there are benefits to not “placing all your eggs in one basket” and having a primary and backup transmission means should one be lost.

Are two transmission methods always required for fire sprinkler system monitoring?

A common misinterpretation is that two transmission paths are always required. This assumption most likely has to do with the fact that for many years digital alarm communicator transmitters (or DACTs) were the default method for monitoring. In its simplest form, DACTs utilize phone lines to transmit the signal to the supervising station and have always been required by NFPA 72 to have two transmission channels. Other monitoring technologies such as cell, radio and internet are approved by NFPA 72 as single communication technologies and are not required to be provided with a backup. In part two, we will discuss the “other” fire sprinkler system monitoring technologies and explain why NFPA 72 is comfortable with one transmission means for some technologies but not others.

A single communication path is required to be supervised at intervals not exceeding 60 minutes. This means the protected premises must check in with the supervising station a minimum of once per hour. This is referred to as a timer test. A failure to check in with the supervising station a minimum of once every 60 minutes must be annunciated (by trouble signal) at the protected premises.

For multiple communication paths, each path must conduct a timer test at intervals not exceeding 6 hours. Failure to successfully conduct a timer test at least once every 6 hours, must generate a trouble signal. When multiple communication paths are used, a single point of failure in the monitoring network cannot negatively impact the alternative transmission channel. This can be an issue with some monitoring technologies (see diagram below). The red circle in the diagram indicates a single point of failure on the transmission channel. Therefore, this arrangement would not be permitted.

fire alarm and fire sprinkler monitoring diagram

Part II

Criteria for how to send sprinkler waterflow and fire alarm signals from the protected premises to the supervising station have caused confusion and raised many questions from installers and code officials alike. The intent of these articles is to clarify the installation requirements and different communication technologies outlined in NFPA 72, to ensure whatever method is chosen meets the requirements of the adopted codes and standards. This article will address requirements specific to digital alarm communicator transmitters, or DACTs.

Digital Alarm Communicator Transmitters (DACTs)

Digital alarm communicator transmitters, or DACTs for short, have been one of the primary methods of monitoring sprinkler waterflow and fire alarm systems for nearly 40 years. Originally approved in the fire alarm code back in the 1980s, DACTs quickly became the default method of fire sprinkler system monitoring up until a few years ago. Put simply, DACTs use phone lines to transfer the fire alarm signal from the protected premises to the supervising station. But do not let the name cause any confusion, the only thing “digital” about a digital alarm communicator transmitter is it dials digits (or a phone number). DACTs became such a common method of monitoring in the 1980s and 1990s that fire alarm manufacturers began adding phone jacks inside fire alarm panels during the manufacturing process to simplify installations.

Installation Requirements for DACTs

DACTs are required to be connected to the fire alarm panel upstream of any customer owned equipment. Customers with a private branch exchange (PBX) network, or a phone system that requires a person to dial 9 to get to an outside line, must be connected downstream of the fire alarm equipment. NFPA 72 does not want the fire panel to dial 9 to get an outside line. There is no requirement in NFPA 72 for the phone lines to be dedicated to the fire panel. The phone lines can be used by the customer for other business functions but monitoring of sprinkler waterflow and fire alarm signals must take precedence over all other uses. To meet this requirement, the phone line(s) must be connected to an RJ31x phone jack (see photo). This device allows the fire alarm panel to seize control of the phone line, disconnect any other uses, and send the signal to the supervising station.

Federal Laws vs. State Laws

One of the challenges was, how does the technical committee establish regulations for an industry (phone companies) regulated by the federal government (Federal Communications Commission)? Keep in mind, federal law supersedes state law. Most codes and standards adopted by jurisdictions are not applicable to federally owned properties or industries regulated by the federal government (there are some exceptions to this). In general, a fire inspector cannot enforce state laws (codes and standards) on federally owned buildings because the federal government is not subject to state law. Since the phone network is regulated by the FCC, there were concerns with how to apply prescriptive requirements in a standard to an industry where enforcement could be an issue. For this reason, proponents of DACTs were unsuccessful in getting their concept approved for use in the fire alarm code on two separate occasions in the 1980s. On the third attempt proponents were successful. They were successful because, unlike their first two attempts, the third proposal included a requirement that every installation have a primary and backup phone line, in case the primary failed. This is the reason NFPA 72 requires DACTs to have two transmission channels. It is important to keep in mind that DACTs are the only transmission option approved for use in NFPA 72 that requires two transmission channels.

2013 Edition of NFPA 72

The 2013 Edition of NFPA 72 made a change specific to DACTs that had a significant impact on their continued use. The backup transmission channel could no longer be a second phone line. The change required the secondary transmission channel to be cell, internet, or radio. In previous editions, and for many years prior to adoption of the 2013 edition, phone contractors would simply bring two phone lines to the fire alarm panel to meet NFPA 72’s requirement for a primary and backup phone line. However, upon adoption of the 2013 edition of NFPA 72 (or any of the more recent editions), this is no longer allowed. This change was made because technology used by phone companies changed/improved significantly over the past 40 years. DACTs were originally approved for use with plain-old telephone service (or POTS) phone lines. Phone companies previously used copper to provide phone service to their customers. However, due to cost, phone companies transitioned from copper to broadband and fiber-optic. This transition created new challenges from a monitoring perspective. Some of the issues include lack of secondary power supply by the phone companies for their equipment (see the 2019 Edition of NFPA 72 section and the inclusion of customer owned equipment at the protected premises that can be disconnected or switched off.

Voice Over Internet Protocol and DACTs

Voice over Internet Protocol, or VoIP for short, is technology that was first introduced in the mid to late 1990s but did not become prevalent as a phone service option for the public until the early 2000s. VoIP converts a person’s voice to a digital signal and allows the customer to make calls directly from a computer, VoIP phone or data-driven device. VoIP cannot be used or connected to a DACT. Because VoIP converts the signal to digital, the information being relayed from the panel to the supervising station will be distorted and delayed. When a customer converts from traditional land-line phone service to VoIP, it is only a matter of time until the panel initiates a trouble signal because the timer test cannot go through to the supervising station (see Part 1 of this series).

The End of the Era?

Since DACTs were the default method used for monitoring for many years, some were under the assumption that all methods used for monitoring needed to have two transmission channels. As mentioned in Part 1 of this series, cell, internet, and radio are all approved by NFPA 72 as single communication technologies and do not require a backup. However, you will still find authorities having jurisdiction that require two transmission means by policy. With the change in the 2013 edition requiring the backup channel to be cell, internet, or radio, why even use a DACT for monitoring? This was the rationale used by the technical committee for the change, which started the gradual decline of new DACT installations, to the point where cell communicators are now the predominant method for new installations.

Part III

You may recall from earlier, the use of DACTs has been in a slow decline since the NFPA 72 technical committee no longer allowed two phone lines in the 2013 edition. So, what other options are available to business owners and contractors? This article will try to answer that question.

Cellular Communicators

Over the past several years, since the use of DACTs have been in decline, the use of cellular communicators has grown exponentially. Essentially, the business owner pays a monthly rate to a cellular provider, such as Verizon or AT&T, to monitor the fire alarm panel and these signals are sent over a cellular line like a phone call made on any standard cell phone. However, unlike your personal cell phone, manufacturers have gone through an extensive testing and listing process to ensure the monitoring equipment is reliable and will quickly and reliably send the signal out to the supervising station. There are currently several manufacturers that have listed and approved equipment available on the market. The location of the cellular communicator is an important consideration when using a cell communicator. Often, the cell communicator is installed at or next to the main fire alarm control panel. If the panel is located at the center of the building behind several solid walls, in a basement, etc., getting the cell signal out of the building can be an issue. All of us at one time or another have experienced unreliable cell signals inside buildings. The same concept applies to cell communicators as well. The fix to this is to install antennas to “boost” the signal strength. In some cases, like in rural areas, the antenna may need to be placed on the roof of the structure to get a reliable signal.


Radio transmitters used for monitoring have existed for years. Options include one-way private radio transmitters, two-way radio transmitters, and mesh radio networks. While this article will not go into detail to explain each type of radio transmitter, know that this type of technology is approved by NFPA 72 as a single communication technology (no backup needed) for monitoring. Some of the more common manufacturers include AES Intellinet, GSM, and Alarm Net.

Internet, or IP, Communicators

With access to the internet rapidly expanding over the last 20 years, it’s no surprise that manufacturers have been wanting to use this technology to fire sprinkler system monitoring and fire alarm monitoring. You may hear the term, IP-DACT when referring to fire alarm monitoring. Don’t confuse this with standard digital alarm communicator transmitters. IP-DACTs essentially connect to the DACT port or phone connection at the fire panel. The IP part of the DACT converts the signal to internet instead of using standard phone lines. For this reason, IP-DACTs are considered a form of internet monitoring and are not considered a DACT. However, IP communicators have an issue that must be addressed to be used as a monitoring technology. NFPA 72 requires all fire alarm systems, including equipment used for monitoring, to have 24 hours of backup power. If an IP communicator is used for monitoring, the internet equipment must be connected to a backup power supply capable of providing power for a minimum of 24 hours. This is often an issue because many business owners do not connect their internet equipment to a backup power supply.

Single vs. Multiple Communication Paths for Fire Sprinkler Monitoring

As mentioned in previous articles, NFPA 72 only requires two communication channels when a DACT is used for monitoring. There is no requirement in NFPA 72 for two transmission channels when using cell, internet or radio as the transmission means. From a technical committee perspective, NFPA 72 defines “reliable” as, how quickly does the fire panel know when monitoring goes down. This does not mean the monitoring network can never go down. We know equipment can fail at any given time for no apparent reason. But from NFPA 72’s perspective, cell, internet, and radio are considered reliable because the panel will know quickly if/when the communication channel fails.

Application and Summary

It is not the intent of this series of blogs to turn you into a fire alarm expert. After all, the issue of fire sprinkler monitoring and how to send waterflow and fire alarm signals is a complicated topic. Rather, the goal is to provide sprinkler contractors and designers with a basic understanding of the fire sprinkler monitoring and supervision requirements from the model codes and standards so you’re better prepared when working on a job site. When a project is nearing completion, we hope the information in this series of blogs will provide you with some background when determining how the sprinkler waterflow signal will report to the supervising station.

The NFSA is Your Premier Resource for Fire Sprinkler Monitoring Questions

The NFSA’s expert of the day program is an excellent resource for answering all your fire protection questions. Our staff sits on several NFPA technical committees and work very closely with a number of standards. With expert of the day, NFSA members ask questions relating to anything surrounding fire protection, from winterization, to fire sprinkler monitoring systems, and everything in between. In one business day, members receive an interpretation complete with citation.

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