What Is the Meaning of Three Alarm Fire?

Multiple-alarm designations, such as "three alarm fire," signify the amount of resources a fire department needs to allocate to an emergency situation. Depending on the municipality, these designations can mean very different things. The term three alarm fire comes from the old systems of fire department communications. These systems, relying on a type of Morse code that used ringing sounds, enabled fire departments to respond quickly to fires anywhere in their city. The designations used today come from the number of rings or "alarms" a fire warranted under the old system of communication.

The Meaning of Multiple Alarms

Although every city has different meanings for multiple-alarm designations, many use "all hands" as the term for one alarm fires, which call for a low-level response. A two alarm fire will signify that more resources are needed; a three alarm fire will need even more. There is no nationwide standard for multiple-alarm designations, so a three alarm fire can mean one thing in a small town and something completely different in a big city. In New York City, a three alarm fire calls for 12 fire engines and 138 firefighters.

History

Although every city's fire department has its own individual history, many advances in organized firefighting originated in large cities. Without an adequate firefighting system, a small fire could quickly turn into a devastating blaze that could wipe out whole neighborhoods overnight. Many people believe that Benjamin Franklin was the first to organize a volunteer fire department, but this is a myth. According to the University of Delaware, Franklin created the first volunteer department in Philadelphia. Boston and several other cities had already developed volunteer departments before him.

The Development of Response Codes

As local fire departments developed, they had to find a way to get to the locations of fires as quickly as possible. Before the advent of the telegraph, this was no easy task. Many cities developed systems of noise signals, such as church bells, handbell ringers and steam whistles. Fire departments developed codes that relayed information about the fire location based on the number of times the signal was sounded. However, signals were often misunderstood, leading to problems.

Multiple-Alarm Designations

After the invention of the telegraph, fire departments were able to set up better systems of communication. New York City and Boston both set up fire reporting systems that used the telegraph. Boston's system used fire boxes spread out across the city to relay a type of Morse code signal to local fire departments, giving them the exact location and severity of the fire. Severe fires were represented by more rings, leading to multiple-alarm designations.

Function

Today's fire departments rely on emergency telephone calls to locate fires. But the old system of fire classification is still used by many fire departments. Generally, the multiple-alarm system is used to tell the fire department headquarters how many of their units will be required in order to deal with a particular emergency. The higher the number of the alarm, the greater the number of resources the department will have to send.

Resources

• "How big is a 10-alarm fire?" from Slate.com