Author(s): Wayne Moore. Published on July 1, 2020.

In Compliance | NFPA 72

When do we sound the alarm?


Recently, the topic of when to sound the alarm was raised on the NFPA Xchange forum. The discussion brought to light a frequently asked question regarding when the notification appliances should operate. Many readers of NFPA 72®, National Fire Alarm and Signaling Code®, assume that all information regarding notification appliances and their actuation would be contained in Chapter 18, Notification Appliances. However, as was stated in last month’s column, it’s important to read and use the entire code—with the singular exception of Chapter 29, Single- and Multiple-Station Alarms and Household Fire Alarm Systems—in order to properly design and install a commercial fire alarm system.

The first direction we receive to sound the alarm appears in Chapter 10, subsection 10.11.1, which states, “Actuation of alarm notification appliances or emergency voice communications, emergency control function interface devices, and annunciation at the protected premises shall occur within 10 seconds after the activation of an initiating device.” That section, at least in general terms, explains that upon detection of a fire, or upon the actuation of any initiating device, the alarm must sound.

The operation of any remaining connected appliances, such as waterflow switches, fire dampers, and smoke doors, and whether they are connected to the fire alarm system is up to the system designer to describe in their operational specifications. For example, NFPA 72 does not specifically require a waterflow alarm initiating device to be connected to the building fire alarm system. Connection to the building fire alarm system would be determined by the requirements established by the authority having jurisdiction, usually as referenced in the locally adopted building or fire code.

The code does require that when the alarm signals are used for occupant notification, there must be at least one notification appliance listed for the purpose in each notification zone of the building, and that the appliances should be located so that they have the characteristics described in Chapter 18 for public mode or private mode, as required. This stresses the need for proper audibility to ensure the alarm signals are heard, and if the systems use voice that the notification signals are intelligible. Of course, the purpose of the alarm notification is to cause the building occupants to evacuate.

There are exceptions to where notification appliances are required. The code excludes notification appliances from exit stair enclosures, exit passageways, and elevator cars. Knowing that the intent of the alarm notification appliances sounding throughout the floor areas is to alert the occupants to evacuate, the technical committee determined that once the occupants are in the exit enclosures, high noise levels and light intensity from notification appliances could cause confusion and impede egress. There may be design or operational conditions that could warrant the installation of notification appliances in exit passageways and stair enclosures, but a careful analysis is necessary to avoid impeding exiting from the building.

It is never necessary to install notification appliances in an elevator—in fact, the code does not allow the evacuation signal to operate in elevator cars. Should an alarm occur, one of two things will happen. First, the doors will open, and the occupants will hear the alarm. Second, if there is smoke detected in an elevator lobby or mechanical room, the elevators will automatically be recalled to a safe floor. The occupants of the elevator will have no opportunity to change the operation, and having the alarm sound in the elevator would not assist them.

The same is true for visible signals, which are not required in elevator cars, exit stair enclosures, or exit passageways, for many of the same reasons we do not require audible notification in these spaces. Ultimately the goal is to ensure the notification appliances operate when and where they are needed. 

Wayne D. Moore is vice president at Jensen Hughes.