Fire Side Chat: Ensuring They Get the Message

Last month, we covered the basics of the life-safety discipline referred to as mass notification systems (MNS). This relatively new technology area aims to disseminate critical information among a large number of people in quick fashion.

The need for accurate, timely info has always been a problem, but recently civilian and government authorities decided it was time to do something about it.

A MNS is not all that different from an emergency voice/alarm communication (EVAC) system. The National Fire Protection Association (NFPA) refers to this type of multipurpose system as an emergency communications system (ECS) in its upcoming 2010 Edition of NFPA 72, National Fire Alarm Code.

Alarm technicians have worked with EVAC systems for years in large buildings, high rises and campus settings.MNS, however, are designed to coordinate all facets of emergency communication from audible warnings to E-mail, fax, computer pop-up windows, televisions, landline telephones, cell phones and more.


No matter which flavor of MNS you examine, the primary goal is to coordinate and unify emergency messages throughout all affected areas in order to reduce confusion and message conflicts. According to NFPA, this is best achieved by integrating EVAC with MNS along with other building sub systems.

The MNS effort began within the Department of Defense (DoD) where it was decided that the fire alarm platform was by far the best place to begin. The survivability and fault tolerant nature of the technology made it a slam dunk for decision makers. It was also decided that fire alarm engineers, installers and service technicians are the most qualified to deal with MNS implementation.

The Technology Behind ECS
There are two basic types of communication and notification systems incorporated in typical high rises, large buildings and campuses. They are one and two-way audio communication systems. Our focus will be one-way MNS.

There are two fundamental components on which one-way MNS are built. They are outdoor, or wide area, systems and in-building, or individual building, systems.

The purpose of an individual building MNS is to convey information within all affected structures as well as the immediate area surrounding them when outdoor speakers are installed on the exterior. Wide area MNS are designed to convey critical information in larger areas outdoors.

A typical in-building MNS consists of: 1) visual strobes; 2) EVAC speakers;3) an autonomous control unit(ACU); 4) a local operating console(LOC); 5) initiating devices; and 6) an interface that links the ACU/ECS to other building subsystems.

Where a fire alarm system requires a fire alarm control panel (FACP) to control input/output (I/O) functions, the MNS side requires an ACU to control all facets of mass notification. When the FACP and ACU are combined to provide an integrated system, they become an ECS.

MNS and Fire Signal Priority
Although MNS technology is built upon the common fire alarm platform, there are changes in how they operate and signal priority of which fire alarm personnel just entering the MNS field must be aware. For example, for many years it’s been a well accepted fact that fire alarm signals take priority over all others, but this is not always the case when MNS is included in the mix.

An example is where a tornado alert is bundled with a common fire alarm system, which is perfectly acceptable under NFPA 72, 2007. With MNS at the helm, if during a storm a fire alarm initiating device happens to detect a fire and the notification appliance circuit (NAC) devices are invoked in an effort to evacuate, the system must immediately change signals to MNS warnings instead.

In this case, the fire alarm condition must still indicate on all control consoles as well as the fire alarm panel, but the NAC devices must change from fire to the appropriate emergency MNS signal. If you’ll recall from last month’s column (find it at, an integrated fire/MNS system employs only one set of speaker/strobes for both fire and MNS signaling.

Priority signaling is also possible using multiple-zone audio amplifiers within the ECS head-end. This means that one message can be issued in certain areas of a campus while an entirely different message plays in another. Live, real-time messages can also be implemented using microphones as part of the LOC units.

By code, LOCs must be secured from use, other than authorized individuals. They must also be placed in a location not accessible to unauthorized individuals with one of them located in an area commonly manned by facility personnel.

Although there can be more than one LOC in a single facility, only one can be used at any a time. A method must be incorporated that indicates which one is enabled and during that time all other LOCs must be rendered inoperable. This is all part of the overall mission of message unification and the reduction of confusion when more than one condition occurs locally. Live, real-time messages take precedence over all else.

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About the Author


Shane Clary, Ph.D., is Security Sales & Integration’s “Fire Side Chat” columnist. He has more than 37 years of security and fire alarm industry experience. He serves on a number of NFPA technical committees, and is vice president of Codes and Standards Compliance for Pancheco, Calif.-based Bay Alarm Co.

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