During a recent presentation, a fire marshal asked whether NFPA 72, National Fire Alarm and Signaling Code, requires that visible signals be deactivated when the audible signals are silenced. I referred him to Section 10.12.2: “When an alarm signal deactivation means is actuated, both audible and visible notification appliances shall be simultaneously deactivated.” 

The obvious answer to his question was yes. But the discussion did not end there. He asked why the technical committee made that change. He was adamant that the visible signal should remain operating when the audible signals were silenced to let the occupants know there was still an active alarm being investigated. His department follows this procedure because the audible signals continuously sounding interferes with firefighters’ ability to use their radios.

Unfortunately, there is nothing presently in the code to accommodate his request. The technical committee even provided additional guidance in Annex A, Section A.10.12: “It is the intent that both visual and audible appliances are shut off when the signal silence feature is activated on the fire alarm control unit. Per the ADA, it is important not to provide conflicting signals for the hearing impaired.” 

Imagine my surprise when I returned home from this presentation and had another fire marshal contact me with a similar question! However, I now had time to answer the question and continue the dialogue more thoroughly.

A history of silencing alarms

First, a little history. Silencing audible signals while leaving the strobes flashing crept into the NFPA signaling standards in the 1980s because one manufacturer had the operational capability for this function. They “sold” this idea exactly as the first fire marshal described—first responders could silence alarms and leave the strobe flashing while investigating the cause of the alarm. 

At the time it was the only manufacturer able to perform in this manner, so it was a specified item used to make it more difficult for competitors to bid projects where this manufacturer was specified. Over time it became the norm, without any substantiation in the code. 

As I understand most fire-response situations, it is expected that all occupants would be evacuating (or already out) as first responders arrive. Once the fire department is on-site, they would maintain control over the building, and no one would be allowed to enter until the all clear is given. 

No training or code language states that flashing strobes without audible signals sounding are defined as “the fire department is investigating—do not enter the building.” 

The only reason for strobes as notification appliances is for deaf and hard-of-hearing occupants to receive the same evacuation signal as hearing occupants. If the strobes remain flashing while personnel—presumably first responders—are investigating, the only signal we are giving that an alarm condition exists is to deaf and hard-of-hearing occupants. And if they have not evacuated, they must. 

That limited use, and the confusion it could cause, seems to be the substantiation given for the change to NFPA 72. Some would argue that allowing this to continue may lead to those in the building who are not first responders believing that as soon as an alarm sounds, they can silence the audible signals and decide if it is a “real” alarm or not. 

Other possibilities?

Obviously, this is not a safe way to treat an alarm signal or something to encourage. But if we think this procedure through, why would we want people to remain in a building when an alarm has sounded? This procedure emphasizes to occupants that when the alarm signal sounds, they can assume it is false until first responders arrive, investigate and give a second cue to evacuate.

Will this result in more people being potentially trapped in a building where there is a real fire—meaning first responders will need to rescue them before fighting the fire? Is this a tradition really born out of false alarm issues, resulting in even first responders believing initial evacuation is not necessary? False alarms are still with us, but it may be more beneficial to look at other methods to avoid these issues, such as stricter enforcement of testing and maintenance. And as an industry, we need to make installed fire alarm systems more credible and reliable.

That means designers and installers should more closely follow the code when designing and installing fire alarm systems. It may make sense to develop a code-­allowed procedure to indicate an active alarm is under investigation. This procedure would perhaps depend on the occupancy, building size or any additional fire protection in place. 

Continually sounding audible signals interfere with first responders’ radio traffic. But we need a safer method that doesn’t conflict with the Americans With Disabilities Act and confuse occupants about the alarm condition. Is there another way?