In 2010, NFPA 72 became much more than just a fire alarm code. It now includes requirements—the majority of which are found in Chapter 24, Emergency Communications Systems—for the installation of fire alarms and emergency
notification systems, indoors and outdoors.
Paragraph 24.2.3 states, “An emergency communications system is intended to communicate information about emergencies including, but not limited to, fire, human-caused events (accidental and intentional), other dangerous situations, accidents, and natural disasters.” This chapter includes one- and two-way communications.
Mass notification systems
One-way communication systems include in-building fire emergency voice/alarm communication systems, in-building mass notification systems (MNS), wide-area MNS and distributed recipient MNS.
Two-way communication systems include in-building wired emergency services communication systems (firefighters’ telephone systems), radio communications enhancement systems, area of refuge two-way emergency communication systems, stairway communication systems, elevator landing communication systems and occupant evacuation elevator lobby communication systems for rescue assistance.
The driving force to develop this chapter was to recognize MNS so emergency voice/alarm equipment, as well as fire alarm signaling, could be used in buildings. MNS are not code-required systems and are mostly voluntary. The military has requirements for them, and you will find them in schools across the country. Each system is unique in its layout and usage, and this chapter helps provide needed information for design, installation and usage.
Emergency signaling for MNS is split into four layers, depending on where the notification will be provided. Layer one is for emergency notification to occupants inside buildings. Layer two is for occupants on the building exterior. Layer three provides notification through individual means, such as text messaging, emails, etc.; and layer four provides for notification through public measures such as radio or television. Designers use this information and select the appropriate layers based on risk analysis for the emergency plan. Remember that a mass notification system can be used for many purposes, including weather-related, geological and human-caused accidental or intentional events.
Survivability in the code
Chapter 24 has the pathway survivability requirements. Chapter 12 describes the survivability levels, but Chapter 24 is the only location I have ever found in the national codes that provides requirements for specific survivability levels for a number of applications. The main reason for pathway survivability levels is to ensure the circuits and pathways will survive for an extended time when notification is not provided to all building occupants at the same time. Pathway survivability must be provided when using partial evacuation or relocation.
For example, paragraph 188.8.131.52.3 states, “Where the building is constructed with a fire resistance rating that is equal to or greater than 2 hours, the installation shall comply with 184.108.40.206.6 or provide a pathway survivability of Level 2 or Level 3.”
There have been a number of additions to the survivability level requirements in recent NFPA 72 editions. They now apply to firefighters’ phone circuits, area of refuge communication systems, elevator landing two-way communication systems, occupant evacuation elevator lobby two-way wired communication systems and stairway communication systems. Note that Chapter 24 also states in 24.3.14 that “Pathway survivability levels for in-building mass notification systems shall be determined by the risk analysis.”
Another interesting fact is that fire alarm signals have historically had the highest priority over other signals, but since mass notification may in some cases be more urgent, some situations allow the MNS to override or take priority over a fire alarm signal. This was primarily brought on by past school incidents where the fire alarm was activated so the students and teachers would be easy targets for an active shooter.
Other chapters of NFPA 72 also contain requirements for emergency notification systems. Chapter 10, Fundamentals, includes requirements for power supplies for these and fire alarm systems. Chapter 14, Inspection, Testing and Maintenance, contains requirements for inspection and testing of emergency systems. Chapter 3 contains definitions for these systems.
Don’t overlook Annex A, either. The technical committees have done a great job providing insight as to the intent of the code language. Back in 2010, when NFPA 72 changed to include other signaling systems, the document’s layout also changed to make it easier for nonfire-alarm users to locate information. The side benefit is that this also helped fire alarm users.
As we all know, codes change regularly to keep up with technology, so always review the current adopted codes in your area for the latest information.
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