Douglas Krantz - Technical Writer - Describing How It Works

What is a Fire Alarm System?

A fire alarm system is a life safety system. It detects fire and warns people of fire danger.

What is a Fire Alarm System?

Greetings Douglas,

Thank you so much for the info on fire alarm systems that you've already sent. I don't understand all the info just yet, but it is getting easier.

I really appreciate you breaking it down.

Thank you, PD

A Fire Alarm System is a Life Safety System

The idea behind fire alarm systems is to save lives and protect property. A fire alarm system does this by detecting fire (either automatically or when someone sees a fire) and then warning everyone in the building about the fire.

A person, having seen a fire, could run down the halls shouting "FIRE". That would get everyone's attention. But there are limits to that. If the building is large, the running down halls will take a lot of precious time. If the doors are closed, the voice will be muffled. If the person running around isn't familiar with the building, some people won't get the message . . . This is also assuming that the fire is noticed before it's too late.

A fire alarm system is faster, louder, and more thorough than a person running . . . and many times, a fire alarm system detects the fire automatically, before anyone sees the fire.

When the fire alarm system detects a fire, it often (but not always) calls the fire department and activates smoke control. Sometimes when it detects a fire, the fire alarm system also suppresses or slows down the fire.


A fire alarm system is an electrical/electronic system. It uses changes in DC (Direct Current) values and electrical impulses to send the life safety signals from the detection devices, to the control panel, and then to the warning devices. It also uses electricity to power the devices.

To understand how the fire alarm system sends its signals and powers the devices, an understanding of electricity and electronics is mandatory.


I can offer some help to you understand fire alarm systems. The subject of fire alarm systems is vast, the books you have are just a little bit of what's involved.

The best way of dealing with helping you is for you to send your questions, and I answer them to the best of my ability in a day or two.

I also have a book available that might be helpful. Make It Work - Conventional Fire Alarms. Many of your questions are organized for easy understanding.

The book can be found at:

Douglas Krantz
Life Safety
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Make It Work Series of Books by Douglas Krantz
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