Muting of Public Address System or Sound System during fire alarm

[Shujinko]

Where in code is there a requirement for muting a Public Address System or Sound System during fire alarm annunciation?

I am looking at NFPA 72 18.4.4.3.1, but this isn't that clear. Nor does it specifically mention a PA or sound system.

18.4.4.3.1  A system arranged to stop or reduce ambient noise shall be permitted to produce a sound level at least 10 dB above the reduced average ambient sound level or 5 dB above the maximum sound level having a duration of at least 60 seconds after reduction of the ambient noise level, whichever is greater, measured 5 ft (1.5 m) above the floor, using the A-weighted scale (dBA).

Is there any other code that would be more specific?

 

[PaulMmn]

Yuck! Can anyone translate that into English? Or American??

It sounds like they're saying a PA system can be louder than the background noise.

I know a lot of PA systems have the capability of playing background music, with an override input for paging (which mutes the background music). Are they talking about one of these?

There are also systems designed to mask office noise by playing 'white noise' at a level to force your ears to 'mute' everything outside your cubicle. You'd think it's a nice, quiet environment until it gets shut off-- and you realize how really noisy it is!

 

[Hv&Lv]

Something to read on...

How to Auto Mute Audio for Fire Life Safety Compliance -

To setup your AV system to mute non-emergency audio during an alarm condition; request the fire alarm company provide a set of dry relay contacts at your AV equipment location. Connect this fire alarm relay directly to your AV systems dry contact inputs for further control. These contacts could...

avdesignguide.com

 

[hbiss]

I am looking at NFPA 72 18.4.4.3.1, but this isn't that clear. Nor does it specifically mention a PA or sound system.

18.4.4.3.1  A system arranged to stop or reduce ambient noise shall be permitted to produce a sound level at least 10 dB above the reduced average ambient sound level or 5 dB above the maximum sound level having a duration of at least 60 seconds after reduction of the ambient noise level, whichever is greater, measured 5 ft (1.5 m) above the floor, using the A-weighted scale (dBA).

Sounds like they are talking about a sound masking system.

The requirement to mute sound systems comes from local fire codes. Obviously in clubs, movie theaters and regular theaters, etc you want to kill the sound when the fire system activates else no one will know. Sometimes there is also an emergency life-safety system that may or may not be a part of the normal sound system. This allows announcements to be made after the sound is muted.

The link by Hv&Lv gives good information, but has to be applied according to the venue. If this is live sound with a band performing you probably would just want to kill their power with a contactor. But if there is an installed sound system like in a movie theater, theater or club you really need to get with the people who do the installation and maintenance on it to see how they want to go about doing this. It's not allways about killing power. They should also be familiar with any code and the requirements.

-Hal