NFPA Today - September 24, 2021

A Guide to Fire Alarm Basics – Off-Premises Signaling and Supervising Stations

A fire alarm system is a crucial part of the overall fire protection and life safety strategy of a building. A fire alarm system serves many functions and the differences between the functions can be a bit confusing, so I created a visual guide to fire alarm basics. The objective of this blog series is to discuss some of the major components and functions of a fire alarm system. For an overview of the entire system take a look at my Guide to Fire Alarm Basics Blog. This blog will take a deeper dive into fire alarm system off-premises signaling and supervising stations.

When talking about fire alarm systems, the term premises includes the entire area monitored by the fire alarm, this could include the entire building or even an entire campus. Off premises signaling is important because it allows signals from the fire alarm system to be sent to a constantly attended location (supervising station or a public communication center) to ensure the proper response.

The purpose of off-premises signaling is to provide dedicated, 24-hour monitoring for a fire alarm and signaling system and to initiate the appropriate response to those signals. In the case of a fire alarm condition (fire detected in the building), the appropriate response usually includes the dispatching of the local fire department or fire brigade. In the case of a supervisory condition, such as a closed sprinkler valve, the appropriate response might be the notification of designated maintenance personnel or outside contractors.


If a fire alarm and signaling system is sending signals off premises, it is either (1) sending signals through a Public Emergency Alarm Reporting System, or (2) the fire alarm system is part of a Supervising Station Alarm System. Regardless of the system, in today’s world they all consist of a type of transmitter at the protected premises that uses a transmission and/or communications channel and pathway to send signals to a receiver at the supervising station or public communications center.



A Public Emergency Alarm Reporting System (PEARS), otherwise known as a Municipal Emergency (Fire) Alarm System is a communication infrastructure, other than a public telephone network that is used to communicate with a communication center. Typically, this communication infrastructure is owned, operated, and controlled by a public agency. The system itself does not include the fire alarm control unit or any of the equipment that is located on the protected premise, instead, it starts at the transmitter and ends at the public communication center.


One way the interface between the fire alarm control unit and the PEARS is completed is using a master fire alarm box, which is an addressable manual pull station on the PEARS system that has an interface circuit that allows a fire alarm control unit to actuate the master box when the system initiates a fire alarm signal.

Large municipalities usually locate the communications center at a facility designed for the purpose. Small communities often locate the communications center at the fire station, police station, sheriff’s office, or a private agency that has been contracted to provide public emergency communications services. NFPA 1221, Standard for the Installation, Maintenance, and Use of Emergency Services Communications Systems, provides requirements for the installation, performance, operation, and maintenance of communications systems and facilities.



If off-premises signaling is provided by a private company, it is most likely completed using a supervising station alarm system.  A supervising station alarm system consists of everything connected to the supervising station, including the protected premises fire alarm control unit and devices.


Supervising Station Alarm Systems are further divided into three specific types. They are

  1. Central Station Service Alarm Systems
  2. Proprietary Supervising Station Alarm Systems
  3. Remote Supervising Station Alarm Systems.



A Central Station Service Alarm system consists of a remotely located supervising station that is listed for central station service to UL 827 Central-Station Alarm Services and, in addition to monitoring, it provides several other services including record keeping and reporting, testing services, and runner service. This can either be required by code or some insurance companies for certain occupancies. This option can also be chosen by a building owner who wants to have a single contract with a provider who supplies monitoring as well as inspection, testing, and maintenance and other services required of central stations.



A Proprietary Supervising Station Alarm System consists of a supervising station under the same ownership as the protected building that it supervises. These can be useful to owners who have very large buildings or a campus or for owners who have numerous buildings in many locations and who are able to dedicate the space and staffing levels to accomplish this. Proprietary supervising stations can be located on the same premises as the fire alarm system or at another location; these are most often used by large airports, industrial plants, college campuses, large hospitals, and retail chains, among other facilities. An example of this is a big box store that has a dedicated location that monitors all of its store locations. Additional fire alarm services including record keeping, equipment installation, inspection, testing, and maintenance are the responsibility of the owner and can be accomplished in-house or be contracted out to an outside contractor.


A Remote Supervising Station Alarm Systems consists of a constantly attended location that receives signals from various protected premises typically owned by different parties. Unlike central station fire alarm systems, contracts for this service are typically limited to the monitoring and recording of signals from the fire alarm system. Additional services including equipment installation, inspection, testing, and maintenance are the responsibility of the owner. This is an option for owners who are not required or do not want to provide central service and for whom a proprietary supervising station does not make sense. It also may be common for a municipality to operate a remote supervising station as a way to receive signals at their communication center if they are not utilizing a public emergency alarm reporting system.

Communications methods

 There are many different methods that can be used for the fire alarm control unit to communicate to the supervising station, and NFPA 72 outlines the requirements for four different types that are permitted in new installations, which includes both wired and wireless methods.

Want to learn more?

Like I noted in the beginning of this blog, if you are interested in learning more about fire alarm basics, take a look at my Fire Alarm Basics Blog. I will be updating this series over the next few months to add a deeper dive into different portions of the fire alarm system. If you found this article helpful, subscribe to the NFPA Network Newsletter for monthly, personalized content related to the world of fire, electrical, and building & life safety.

Download the Fire Alarm Basics Fact Sheet
Shawn Mahoney
Technical Services Engineer with a masters degree and PE in fire protection supporting subjects throughout the association

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