Days Gone By

The fire alarm systems industry has changed considerably over the years. Many old-timers can remember a fire alarm system that only detected a fire and sounded an alarm. Nonfire alarm systems did not interface with these fire alarm systems. They consisted of a simple relay-based control system with detection devices and horns or bells for notification. (You see, I really am old!) A contractor could easily install such a fire alarm system and troubleshoot any problems with a simple voltmeter and a screwdriver.

Then, as time marched on through the solid-state electronics years, the systems became a little more complicated. And, on top of the equipment complications, more nonfire systems began to become interfaced with the fire alarm system. In some cases, the fire alarm system actually controlled some of the interfaced systems. In others, the fire alarm system monitored the integrity of the interfaced systems.

Of course, to ensure that these controlled or monitored interfaced systems worked in concert with the fire alarm system without interfering, the codes had to change.

As buildings became taller and more complicated, so did the fire alarm systems. Designing and installing a fire alarm system, especially if it included voice communications, was no longer simple.

We arrive at the present day among all kinds of new threats to the occupants of our buildings, many of which do not directly relate to fire. But today, we also have computer-controlled fire alarm systems that can definitely provide whatever we need in the form of control, communications, monitoring and protection.

If you install fire alarm systems in today’s marketplace, you have already been exposed to the emergency control functions now interfaced with a fire alarm control unit: elevator recall, smoke damper closure, magnetic door hold-open release, fan shutdown, smoke control, door unlocking, and gaseous extinguisher systems release—just to name a few.

Essentially, the fire alarm system can monitor any other system that can change a relay state: low building temperature, basement high-water level, industrial process operations, excessive heat in a chemical-based process, ammonia leaks in a refrigeration cooling system, or a chemical leak or overflow condition in a chemical process. Where any such conditions pose threats to the life safety of the occupants, their signals must receive the appropriate priority when reporting to the control system and, ultimately, to a monitoring system.

Additionally, the emergency voice alarm communications systems (EVACSs) have morphed into mass notification systems (MNSs), requiring expertise that, before now, a contractor rarely needed. If we begin by examining signal priorities, it will become clear how far we have advanced in the use of fire alarm systems for more than just fire detection. In fact, the previous editions of NFPA 72 required a fire alarm signal to take precedence over all other signals, with no exceptions. NFPA 72 2010, the National Fire Alarm and Signaling Code, changed all that.

For the first time in the history of fire alarm system codes, a message from an MNS may override a fire alarm signal. However, to do so, the stakeholders—including the authority having jurisdiction (AHJ)—must conduct a risk analysis in accordance with Chapter 24. Based on this risk analysis, the AHJ must give his or her approval to the change in priority.

As stated in the Annex A of the code, “Mass notification signals might, at times, be more important to the building or area occupants than the fire alarm signal.” And obviously, once the stakeholders complete a risk analysis, they may determine that they will not allow some messages to take priority over fire alarm signals.

Other than that exception, fire alarm signals must still take priority over all other signals.

In NFPA 72 2013, eight requirements affect fire alarm signal priorities. The code then lists the priority status of all other signals that a fire alarm system may provide, including the following:

• Emergency MNS signals and messages will have priority over supervisory and trouble signals based on the requirements of Chapter 24.

• Carbon monoxide signals are permitted to take precedence over supervisory and trouble signals.

• Pre-alarm signals take precedence over supervisory and trouble signals.

• Supervisory signals must take precedence over trouble signals.

• Hold-up alarms or other life-threatening signals must be permitted to take precedence over supervisory and trouble signals where acceptable to the AHJ.

The code also allows that, where an owner chooses to have separate systems installed, these separate systems may achieve the priority of signals in accordance with the requirements outlined in Section 10.7.

One of the less obvious signal priorities is the last item on the list. When a system is monitored that relates to any life-threatening hazards, that signal may take priority over any supervisory or trouble signals. This allowance becomes very important in ensuring the proper notification of the occupants to dangerous nonfire conditions and to the first responders on the scene to mitigate the hazard.

Thus, the code permits the stakeholders to mandate that the signal warning for a life-threatening hazard take precedence over every other signal except fire and certain MNS messages. This process allows the owner to have the signals prioritized in accordance with the facility’s emergency response plan.

In addition, whenever an override occurs on circuits affecting monitored signals—especially those of a life-threatening nature—the override should be indicated at the control panel for each system to ensure all signals are restored to normal.

As you can see from this description, in the good old days, a contractor did not need to understand risk analysis. The contractor also didn’t need to understand how the operation of MNSs fit into the emergency response plan for a facility. Obtaining training in these areas can often prove difficult, but is a very useful resource to provide the basic understanding of these concepts.

In contrast with the good old days, the current code also requires that the voice messages meet the requirements for intelligibility and that stakeholders develop appropriate messages for each scenario in the emergency response plan.

Furthermore, the code requires that the stakeholders develop a template for each message required. This requirement exists because the fundamental structure of prerecorded or live messages will prove critical in providing information and instructions that the occupants can intelligibly perceive. As the code advises, “Prerecorded messages created in a controlled environment are considerably more intelligible than live messages and should be developed and provided to handle as many of the probable emergencies that a particular facility will encounter.” This really means that, as a contractor, you will need to coordinate all of these issues with the owner, the designer of these new systems, and with the other stakeholders.

The above represents just a few examples of how the fire alarm system installation business has become more complicated. As a contractor in today’s changed environment, you need to understand these shifts to lessen the complications encountered during an installation and to ensure you can reliably install these newer fire alarm systems as you did when such systems were less complex in days gone by.

About the Author

Wayne D. Moore

Fire/Life Safety Columnist

Wayne D. Moore, a licensed fire protection engineer, frequent speaker and expert in the life safety field, is a principal member and past chair of NFPA 72, Chapter 24. He is a vice president with Jensen Hughes at the Warwick, R.I., office and can be...

Stay Informed Join our Newsletter

Having trouble finding time to sit down with the latest issue of
ELECTRICAL CONTRACTOR? Don't worry, we'll come to you.