Douglas Krantz - Technical Writer - Describing How It Works
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How does the Fire Alarm Box-on-the-Wall in the Bedroom Work?

The box on the wall of the apartment's bedroom is a fire horn connected to the apartment building's fire alarm system. If that sounds off, the building could be on fire, and you have only a short time to get safely out of the building.

I have a question about something


Mr. Krantz

I moved into a 1-bedroom apartment recently that has 3 smoke detectors (the flat, round kind mounted on the ceiling), but also mounted on one wall is a red strobe alarm that I believe, through web research, to be a Gentex Commander 2 alarm, probably installed in 2004 when the complex was built.

Could you tell me how this operates, and especially what activates it? There is no "pull handle" near my apartment, or on the device itself. I was wondering if perhaps the smoke detectors trigger it, or if a pull handle elsewhere at the apartment complex (a common hallway, etc.) activates it. It seems like a rather commercial-looking object for a small apartment and I'm considering covering it with a picture, as I wouldn't need a strobe to find my exit, and it's a real eyesore. There are also several sprinkler heads in the ceiling covered with pod-like covers. Would it be safe to cover the alarm?

Thank you.

Harry Flanagan

You mention 3 different fire safety features of the apartment building you're in.

Smoke detectors on the ceiling are there to give you an alert quickly that there's even just a little smoke starting to build up in the room. Breathing smoke from the materials in your apartment can and will kill you, so this safety feature gets you out of danger quickly before the smoke becomes a real danger.

Sprinkler heads are there to protect the property and prevent the rapid spread of fire that's already in the room. For the sprinkler head to spray water, the temperature of the room is already quite high, and by that time you should have left the apartment.

The red Gentex (Brand Name) strobe alarm is called a "mini horn/strobe". It is actually connected to the common fire alarm system of the whole building. The common fire alarm system is activated by any pull stations next to stairs or exits, by smoke detectors in the hallways of the building, and by water flowing out of a sprinkler head anywhere in the building. When this sounds off, you need to get out of the building right away. On the way out, just don't breathe any smoke if you don't want to be carried the rest of the way out by the firefighters.

The reason that this mini horn/strobe is inside your apartment is that the sound of the alarm out in the halls is quieted quite a bit by the apartment walls. If the sound is just in the halls outside the apartment, some people can sleep through the building alarm sounds. To wake up everyone if there's a fire detected in the building, these sound off near the people living inside the apartment.

I know it's an eyesore, but the mini horn/strobe is there for your protection. Covering up the strobe means it doesn't get your attention and covering up the horn means it becomes muffled. Don't cover it, just pretend it's part of the apartment and ignore it. If you leave it alone, someday it just may save your life.

Douglas Krantz
Mr. Krantz

Thank you so much, Mr. Krantz, for your quick response and thorough and detailed answers to my questions. I had spent quite a bit of time on this on the internet and just found myself going around in circles, never getting close to the explanation you've given me. I'm so glad I came across your site and am grateful for your time, expertise, and obvious desire to help people. A rarity!

Thank you.

Harry Flanagan

Based on his electronics training, and his understanding of Life Safety, Douglas Krantz has compiled his knowledge of Conventional Fire Alarm Systems into the book Make It Work - Conventional Fire Alarms. The book covers the basics of the Conventional Fire Alarm System, and shows how Life Safety and internal supervision affects the fire alarm system.

Douglas Krantz -- Fire Alarm Engineering Technician, Electronic Designer, Electronic Technician, Writer

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