Many Systems, One Control

Published On
Jun 15, 2016

If you don’t agree that a fire alarm system is more than a fire alarm system, you should probably revisit Chapter 21, Emergency Control Function Interfaces, in NFPA 72 2016, National Fire Alarm and Signaling Code. It defines emergency control functions as, “Building, fire, and emergency control elements or systems that are initiated by the fire alarm or signaling system and either increase the level of life safety for occupants or control the spread of the harmful effects of fire or other dangerous products.”

Code Annex A explains that, “Emergency control functions are meant to be observed functions, not equipment or devices. Examples of emergency control functions are fan control (operation or shutdown), smoke damper operation, elevator recall, elevator power shutdown, door holder release, shutter release, door unlocking, activation of exit marking devices, and so forth. Fans, elevators, smoke dampers, door holders, shutters, locked doors, or exit marking devices themselves are not emergency control functions.”

The issues a contractor encounters when providing the proper connections to actuate the emergency control functions vary but almost always involve coordination with other trades and a knowledge of what the emergency function provides. Some functions, such as fan and damper control, will seem easy to understand. Upon fire detection, the fire alarm system needs to shut down a heating, ventilating and air conditioning (HVAC) unit; start one up; or close or open a damper. The mechanical contractor will install the fan controls and dampers, so it behooves the fire alarm and mechanical contractors to communicate with each other as to who will have the responsibility for the emergency control function.

Often, the fire alarm contractor assumes that, if the relay or addressable control module connects to the fire alarm control unit (FACU) and the cable from that connection extends to the HVAC unit or the damper, it has done its job. However, during final testing, when the authority having jurisdiction (AHJ) asks to witness the operation of the emergency control function and it fails, the AHJ will likely consider the fire alarm test a failure. It makes sense for the contractor to ensure these emergency control functions connect all the way to the controlled device and function properly during the fire alarm system pretest.

Fire alarm contractors can check many of the emergency control functions, such as door hold-open and locked-door-releasing devices, before the AHJ arrives for the final test. Pretesting other emergency function control devices may prove more difficult to coordinate. These functions connect to the FACU, so contractors must coordinate their connection and operation.

Each emergency control function has different requirements. For example, when the specifications call for Elevator Phase I Emergency Recall Operation, contractors must install additional smoke detectors for the recall operation to work properly. In addition, it is the contractor’s responsibility to program the FACU to ensure the designated level recall and the alternate level recall operate properly.

The initiation of a Phase I recall of the elevators may only come from smoke detectors located in the elevator lobby, elevator hoistway, elevator machine room, elevator control room and elevator control spaces. However, local codes or the AHJ can modify this requirement. Also, contractors should remember that NFPA 72 specifies the spacing requirements of the lobby smoke detectors located on the ceiling within 21 feet of the center line of each elevator door within the elevator bank under control of the detector.

In some cases, the elevator lobby location precludes the installation of a smoke detector. For example, in Annex A, the code states, “Smoke detectors should not be installed in outdoor locations or locations that are open to the weather (such as unenclosed elevator lobbies in open parking structures), because such environments can exceed the parameters of the detector listing and can result in unwanted alarms.”

Fire alarm contractors must recognize these issues before the installation and obtain guidance or permission from the AHJ regarding the use of a device that will properly initiate recall but not cause nuisance alarms. Smoke detectors provide the earliest detection for the enclosed lobby scenario, but when the environment will adversely affect smoke detector operation, contractors may want to use other automatic fire detection devices for elevator recall, such as a heat detector. The code allows this.

When using heat detectors, contractors should consider both detector temperature setting and time-lag characteristics. The consideration of a low temperature rating alone does not always guarantee the earliest response.

Fire alarm systems may initiate a wide variety of emergency control functions. In fire alarm system installation, contractors must become familiar with both the operation and the proper connection methods for these critical emergency control functions. Waiting until the final acceptance test to learn their importance can be costly.

About the Author

Wayne D. Moore

Fire/Life Safety Columnist

Wayne D. Moore, a licensed fire protection engineer, frequent speaker, writer and expert in the life safety field, has been a principal member and chair of NFPA 72, Chapter 24, as well as a former principal member of NFPA 909 and NFPA 914. He is the...

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