Is That a Fire Alarm or a False Alarm? Advancements in fire alarm technology since 1871

Great Chicago Fire of 1871
Published On
Oct 15, 2021

The Great Chicago Fire started on Oct. 8, 1871. One of the most significant fires of its time, it left around 300 dead and 100,000 people homeless. The fire occurred in a mostly residential area, destroying over 17,000 buildings in an area of less than 4 square miles.

The actual cause has been the subject of much debate over the years. (It was probably not Mrs. O’Leary’s cow.) The fact that it spread so quickly and affected so many people and buildings got everyone’s attention. The fire received a lot of press coverage. One mayoral candidate would even run on a platform of instituting a stronger building code.

Another fire started the same day in the little-known town of Peshtigo, Wis. The Peshtigo fire destroyed 12 communities over an area of 1,875 square miles. The death toll was estimated to be 1,200–2,400. When I see such a wide range of numbers, I question the sources. The numbers are justified by the degree of destruction, which made recovery difficult. Our society today is far more concerned with determining the exact number of victims than in 1871.

On the 40th anniversary of the Great Chicago Fire in 1911, President Calvin Coolidge issued a proclamation for the first Fire Prevention Week. Every year, the National Fire Protection Association promotes fire safety education by sponsoring Fire Prevention Week.

The electrical industry’s role in fire prevention and protection

The National Electrical Code, one of the original fire codes, was transferred from its original sponsors to become an NFPA- sponsored code in 1911.

Work on fire alarm system requirements began in 1898. NFPA sponsored several different fire-alarm-related standards that covered the various pieces of fire alarm systems, which eventually became a unified document known as NFPA 72, the National Fire Alarm Code. I was fortunate to serve as the secretary and staff liaison to the committees that unified those pieces. A later name change to represent a broader scope resulted in the current title, the National Fire Alarm and Signaling Code.

The NEC and the National Fire Alarm and Signaling Code play an important safety role in preventing or controlling large fires. Fire alarm systems and their electrical infrastructure have saved countless lives by alerting occupants of the need to evacuate.

Once the domain of only commercial and industrial properties, most residential properties today have at least smoke alarms. Some have fire alarm systems that notify an alarm company, which in turn notifies the local fire department. Our homes have become safer as a result.

However, smoke alarms don’t last forever. In fact, research indicates that after 10 years of service, the failure rate tends to increase. Will they all fail at once? No—but they will become less reliable. Now, NFPA 72 requires smoke alarms be replaced every 10 years. The good news is that they have dropped in price dramatically over the years.

Fire safety on the road

We have learned a lot about fire safety in the 150 years since the Chicago and Peshtigo fires. Automatic commercial and industrial sprinkler and fire alarm systems and residential smoke alarms are common—but are these advances enough? As we emerge from the pandemic and start to travel again, how safe are we when we are not sleeping at home?

In my years with NFPA, hotels became my second homes. I became very comfortable, perhaps too comfortable, because it was an environment where I had very little control. After attending a meeting in Savannah, Ga., I retired for the evening. At some point, the fire alarm system went off. I immediately called the front desk and was told that it was a false alarm. That immediately set off the alarms in my head.

When I was a teenager, I worked in two different hotels. From those jobs, I learned that hotel staff were poorly trained and rarely stayed long. Later, as city fire department dispatcher, I learned that fires in hotels weren’t uncommon. I immediately evacuated in Savannah.

I went to the lobby, where the front desk clerk was answering call after call with the same message “false alarm.” I decided to hang out near the front desk for a while to see what was going on. A few minutes later, a member of the maintenance staff came up to the desk. The clerk asked him to go “check the corridor on 2-south, we have a smoke detector going off. I think it’s a false alarm.”

The clerk’s lack of certainty had not been conveyed on any of the calls that I heard, and it certainly wasn’t communicated to me! Everyone had been assured that it was a false alarm, but the clerk had no idea whether it was or not.

A few years later, I was staying on the ninth floor of a hotel in Toronto. Again, there was a late-night fire alarm. I again called the front desk. The answer was, “I know. We think that it is a false alarm. Do you want me to call you back?” I said no, I am evacuating. When I got to the lobby level, I noted a lot of people were there, wearing pajamas. I proceeded outside, where I saw some firefighters. I asked one of them what was going on. He told me that they had a fire in a closet up on the ninth floor.

After the all-clear was given, I went back up to my room. I found that the staff were working on resetting a manual pull station right near the door to my room. I guess that “false alarm” was pretty close. Why did I choose to evacuate? Because it was quite possible that the call would come too late, and it was also possible that the front desk staff members could be forced to evacuate before they could make those calls.

Unfortunately, many of us tend to assume that fire alarm signals are false alarms. I also believe that some fire alarm notification appliances are not all that distinctive. Several years ago, two friends of mine were visiting from out of town, and both stayed at a nearby hotel. One of them is a “fire buff,” or someone who follows what is going on with the fire service.

We were talking in one of their rooms, and at one point, we heard sirens and saw a couple of engine companies and a ladder company coming down the road in front of the hotel. They turned into the parking lot. We looked down and noticed that smoke was coming from the ballroom area. We then realized that the chime sound in the background was actually the fire alarm system. It did follow the temporal pattern called for in NFPA 72, but it wasn’t particularly distinctive. We evacuated, but noted that we didn’t have much company outside.

The temporal pattern, known in the fire alarm industry as the temporal three, has been standardized in NFPA 72 for several years to have something that could get international acceptance.

Prior to the temporal three, many fire alarm systems used what was known as the slow whoop. The slow whoop sounded somewhat like the conventional electronic siren that was used around North America and in some other parts of the world.

Some European counties use two-tone (high-low) sirens. I often observe a general disregard of fire alarm horns and strobes, and that incident did not make me a fan of the temporal three. NFPA changed out its fire alarm system several years ago from the slow whoop system. The new system has the temporal three, but very few on staff knew that they system had been changed. When it first went off, several asked “What is that sound?”

I was in a major retail store recently where the horns went off, and I didn’t see any reactions from shoppers or staff.

In the 150 years since Oct. 8, 1871, we have gained the tools to make us safer. However, fire alarm systems are useless if you don’t trust them. If false alarms are a frequent problem, the issue should be investigated and corrected to prevent recurrence. Fire alarm system reliability can be improved where the maintenance requirements of NFPA 72 are implemented.

About the Author

Mark Earley

Mark Earley, P.E., is an electrical engineer. Retired from the National Fire Protection Association, he was secretary of the National Electrical Code Committee for 30 years and is president of Alumni Code Consulting Group.

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