January 30, 2008 | | Comments 8
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Reducing alarm decibel levels, NFPA 72 style

I was chatting with someone about the decibel level that fire alarms must be set at, and I thought, “Hey, a nice blog idea.”

The National Fire Alarm Code (NFPA 72) requires fire alarms to have an output (i.e., sound level) at least 15 decibels above the average ambient sound level or 5 decibels above the maximum sound level having a duration of at least 60 seconds, whichever is greater. You measure this decibel level 5 ft above the floor in the occupied area.

That said, NFPA 72 does say that audible signaling volume can be reduced, or in some cases, eliminated, when:

  • Approved by the AHJ (generally the local fire department)
  • Visible signaling is in place

If a fire alarm horn is so loud that the PA announcement can’t be heard, I would consider that an improvement opportunity and time to call the fire inspector.

Entry Information

Filed Under: Life Safety Code

Steve MacArthur About the Author: Steve MacArthur is a safety consultant based in Bridgewater, Mass. He brings more than 30 years of healthcare management and consulting experience to his work with hospitals, physician offices, and ambulatory care facilities across the country. He is the author of HCPro's Hospital Safety Director's Handbook and is contributing editor for Briefings on Hospital Safety. Contact Steve at stevemacsafetyspace@gmail.com.

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  1. Mac, this issue is particularly important when considering neonates. Studies find that noise (and lighting) can have adverse developmental effects on small infants.

  2. If the budget will allow – upgrade and eliminate the Fire alarm horn – by discussing with the AHJ, the means to use private mode in lieu of public mode evacuation requirments – hospitals are allowed by the Code/AHJ to have planned evacuation using private mode notification. “chimes” versus those annyoing horns.

    but even better -I Highly recommend using
    voice evacuation notification…in such emergency situations, the AHJ will allow the Local fire warden to give commands (AKA the security personel or nurse call station at the front desk)for a coordinated and planned evacuation for ambulatory care facilities – so the the Fire alarm is the Public announcment – otherwise the PA is required to be fully disabled. The usual adopted code generally requires the Evacuation signal to overide all other notifications -In other words -one should not be able to hear the PA anyway.

    THe PA system would have to be a listed, FM/UL approved equipment for such emergency notification – a bogen, TOA or Common off the shelf equipment is not. IF your PA is listed, get rid of those horns.

  3. The decibel volume on these newer alarms with the flashing lights are excruciating. I ended up seeing a dr. after the school where I work did a fire drill and I was only about 5 feet away from the alarm. i was diagnosed with Acoustic Trauma (Explosive). My inner ear was very tender and hurt, but thankfully no damage. The pain subsided the next day. However, I am so fearful of another alarm. I almost fell over from the shock of it like a gun going off next to your head, but it doesn’t stop. I don’t see how this can be safe. I didn’t have students with me at the time, but if I had I don’t think I could have helped them if they needed help because I couldn’t take my hands off my ears. I don’t have children (my own) in school any more, but I would be furious if I did. This must be damaging to tender ears. There seems to be no reason for it so loud in a school where everyone hears, AND there are flashing lights AND there is a teacher in charge AND examples to follow of classmates leaving the room. these are set excessively loud for very deaf people, but because of the above reasons no need in a regular public school. The sound is so EXCRUCIATING.

  4. I agree with the previous comment. The school fire alarm where I teach is painful to my ears and many students. The foolish school head said I was a bad example by putting fingers in my ears (as many students do also), when actually the students should be encouraged to do the same if the sound level is painful. The decibel level is way too loud.
    I read that the db level should be 15 more than the ambient sound. Ambient sound of educational facility is 45, so the alarm should be at 60 decibels. My guess is my school level is near or above 100 decibels.

  5. They only sell fire alarm horns in the range of 75-90dBA, with most at 80dBA. Simplex sells a (legal) attenuator pad that reduces loudness 5-6dB. The loudness is both a signal and an incentive to get-out-of-there.

  6. Teachers and those with experience with Children with Special Needs will tell you of the disorder, and chaos that happens in their classrooms when the alarms go off. Many Children, especially those with Autism, feel actual pain, and trauma, and sometimes a lifetime of PTSD, as a result of the alarms. Our son, now 33, is one such person. He has been working hard to bring attention to this matter. As a result of his inquiries, the NFPA is presently doing a study on this issue. This is an important an timely subject, thank you.

  7. My previous entry related to our son, but I’d like to share an experience I had in a Hotel when the alarm went off. The sound was excruciating. So loud that I was unable to help people from a neighboring room that did not speak English. All I could do was point to the exit sign, finally taking one by the arm and leading him out. The sound was so loud, it made it difficult to think. It was really an impediment to safe evacuation.

  8. We just had a test of a new fire alarm system that was seriously so loud I’m sitting here with a throbbing headache. As Randy pointed out trying to explain to foreign students that missed the announcement that it was just a test was difficult and almost impossible.
    Randy, do you have a link to the NFPA study or more information as to the status of that study?

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