Fire Alarm Mute Speakers

[Fire Guy]

I am a fire alarm contractor working in a church that has been required to upgrade their fire system. The sanctuary seats over 1000 so the fire system has to be a voice evacuation system. We have installed separate amplifiers, as well as speakers and strobes in the sanctuary. The fire department has a dedicated microphone to override the speakers if they want to.

I have to meet many requirements such as ADA strobe spacing, intelligibility, and supervision.

One of the requirements is to have the evacuation message 15db louder than the ambient sound of the church. When the sound system is on the fire alarm speakers would have to be screaming loud. The fire code puts a cap on max db. So to fit between the 15db above ambient and max 120db I need to shut down the building sound system during a fire alarm. I have a fire alarm relay to do that but I am looking for the best way to shut down the system without damaging any equipment. I was thinking of just powering down the mixer board what do you think?

[Arlin]

Generally, the safest and least distracting way to power-down the system is to just power down the amps.
No thuds or booms that way.

[cmchamp]

If the church has a seating capacity of 1000+, there's more than likely a power sequencing system on the audio, OR a DSP that can be RS232 or other protocol controlled to mute the mains.
IF power sequencing, check the make/model of the main controller, check with the manufacturer and see how to best tie in a remote shut off.

[Gracetech]

Just finishing a new building we went through this. The electrician actually was trying to wire in the system when i stumbled upon him. I politely told him to get out of my rack. As you have heard it's best if your system allows it to do a low voltage signal to your dsp to temporarily mute the system. This requirement was thrown in at the last minute by our Fire inspector. The room was to be exempt from this requirement but we ended up getting the greenhorn inspector that came up with all sorts of stuff we had to do. To appease the inspector we did a remote mute through our dsp since it just so happen to be capable of it.

In venues that fall into the requirement of needing this i have had to do other tricks as well. One inspector wanted instant off and with capacitors in the amps they were taking a few seconds to go out. We ended up having to put in relays for all of the loudspeaker wiring in that project just for a few measly seconds.

Lots of ways to accomplish this code meeting application just be aware that some inspectors have a different way of viewing things.

crt

[Brad Weber]

Originally Posted by Gracetech

Lots of ways to accomplish this code meeting application just be aware that some inspectors have a different way of viewing things.

Very true, I had one arena where the AHJ would not accept anything other than the amplifiers being powered off while in most cases muting via the DSP or powering down the mixer or DSP via the power sequencer is acceptable.

[liko81]

I work in the video surveillance/monitoring field, so we have to deal with this ALL the time, shutting down background music or other "low-priority" audio, so we can come over the intercom system, and/or when the fire alarm (connected to the main panel) is pulled.

Method number 1, if available, is to hook into whatever "remote mute" capabilities are available in the audio system. Most systems intended for commercial audio have this, because the requirement that fire alarms mute audio systems is so common in building codes. It's usually as simple as hooking two bare wires or an RCA plug into the back of the system, and running that to the board which is programmed to energize that circuit as if it were a relay (that's usually exactly what it is) when the fire alarm is pulled.

Method number 2 is to put our own relay into the signal line from the muzak player (in your case that would be the mixer outs) to the distribution/power amp or DSP. The relay will control continuity of the "hot" leg of the signal line, and be "normally closed", but the main panel will trip the relay when the fire alarm is pulled, opening the signal circuit and muting audio. You can usually hook several of these relays in series or parallel off of one panel circuit, to control the "signal outs" from the mixer to multi-zone speaker systems. Virtually all amplifiers have no trouble with this; the problem, if any, comes when the relay is closed again, as you may get a "pow" through the speakers when the signal connection is restored (like plugging in/disconnecting a guitar or a microphone when the system's on and live).

Method number 3 is one of the ones mentioned; use a similar relay to sever the speaker circuit. In most of our installations this isn't a huge deal; the speakers and amps involved are your typical 70V intercom variety and they can handle a hard disconnect of the speaker line (the amp also feeds a large number of speakers in series so one relay can shut down half the store's speaker system). For PA speakers that's a little rougher treatment, and the power involved is much higher, so if they have nice speakers pumping muzak into the store we encourage one of the previous methods.

Method 4 is the harshest; use the relay to sever the "hot" leg of the power supply to the audio system, and/or control a power sequencer or PDU. A power sequencer with the ability to respond to a relay command is not terrible, but if we have to actually set up the relay to cut the hot leg of the power cord, we've exhausted all other options.

[wogster]

Originally Posted by liko81

I work in the video surveillance/monitoring field, so we have to deal with this ALL the time, shutting down background music or other "low-priority" audio, so we can come over the intercom system, and/or when the fire alarm (connected to the main panel) is pulled.

Method number 1, if available, is to hook into whatever "remote mute" capabilities are available in the audio system. Most systems intended for commercial audio have this, because the requirement that fire alarms mute audio systems is so common in building codes. It's usually as simple as hooking two bare wires or an RCA plug into the back of the system, and running that to the board which is programmed to energize that circuit as if it were a relay (that's usually exactly what it is) when the fire alarm is pulled.

Method number 2 is to put our own relay into the signal line from the muzak player (in your case that would be the mixer outs) to the distribution/power amp or DSP. The relay will control continuity of the "hot" leg of the signal line, and be "normally closed", but the main panel will trip the relay when the fire alarm is pulled, opening the signal circuit and muting audio. You can usually hook several of these relays in series or parallel off of one panel circuit, to control the "signal outs" from the mixer to multi-zone speaker systems. Virtually all amplifiers have no trouble with this; the problem, if any, comes when the relay is closed again, as you may get a "pow" through the speakers when the signal connection is restored (like plugging in/disconnecting a guitar or a microphone when the system's on and live).

Method number 3 is one of the ones mentioned; use a similar relay to sever the speaker circuit. In most of our installations this isn't a huge deal; the speakers and amps involved are your typical 70V intercom variety and they can handle a hard disconnect of the speaker line (the amp also feeds a large number of speakers in series so one relay can shut down half the store's speaker system). For PA speakers that's a little rougher treatment, and the power involved is much higher, so if they have nice speakers pumping muzak into the store we encourage one of the previous methods.

Method 4 is the harshest; use the relay to sever the "hot" leg of the power supply to the audio system, and/or control a power sequencer or PDU. A power sequencer with the ability to respond to a relay command is not terrible, but if we have to actually set up the relay to cut the hot leg of the power cord, we've exhausted all other options.

One wonders though, this all makes sense with muzak type systems, or even PA systems, but in the case of live audio with an operator, I'm not so sure. I think it should be sufficient to have a fire alarm light behind the desk, and then when the alarm goes off, the operator drops the mains and monitors, when the fire chief shows up, hand him a microphone and use the system to allow the FD to make required announcements.

[Brad Weber]

Originally Posted by wogster

One wonders though, this all makes sense with muzak type systems, or even PA systems, but in the case of live audio with an operator, I'm not so sure. I think it should be sufficient to have a fire alarm light behind the desk, and then when the alarm goes off, the operator drops the mains and monitors, when the fire chief shows up, hand him a microphone and use the system to allow the FD to make required announcements.

There are numerous problems with this...

What if the operator is a volunteer, visiting engineer, etc.? What if the operator is distracted when the alarm triggers? What if they panic? To a great degree the goal with life safety systems is to remove the human element where panic, being prevented from responding, etc. might have a negative impact.

What happens in the interim between an alarm triggering and the authorities being able to make an announcement? And do they have to make separate announcements for, and in, multiple spaces or is it possible to address the entire building or affected area?

What control or standardization is there regarding the ability of the audio system to serve a life safety function? In the EU and especially the UK many audio systems at stadiums, arenas, etc. support both event audio and life safety functions, however those systems have to meet stringent requirements in terms of the equipment used, system monitoring to insure proper operation conditions, the system intelligibility and other system performance factors and so on. Such systems are designed, tested and operated specifically to serve both roles and systems that are not designed specifically for such use may not meet the associated requirements.

[wogster]

Originally Posted by Brad Weber

There are numerous problems with this...

What if the operator is a volunteer, visiting engineer, etc.? What if the operator is distracted when the alarm triggers? What if they panic? To a great degree the goal with life safety systems is to remove the human element where panic, being prevented from responding, etc. might have a negative impact.

What happens in the interim between an alarm triggering and the authorities being able to make an announcement? And do they have to make separate announcements for, and in, multiple spaces or is it possible to address the entire building or affected area?

What control or standardization is there regarding the ability of the audio system to serve a life safety function? In the EU and especially the UK many audio systems at stadiums, arenas, etc. support both event audio and life safety functions, however those systems have to meet stringent requirements in terms of the equipment used, system monitoring to insure proper operation conditions, the system intelligibility and other system performance factors and so on. Such systems are designed, tested and operated specifically to serve both roles and systems that are not designed specifically for such use may not meet the associated requirements.

There are really two issues at work here, an engineer whether a volunteer or visitor, needs to be familiar with the fire safety plan, and if that includes shutting the system off when there is a fire, then they need to be familiar with it. There is also the issue of, availability, if the system is automatically shutdown by electronics, then it ceases to be a possible way of communicating.

Part of the issue is that building codes are not always worded properly, for example a large place of assembly, where the legislators intended it to be applied to a stadium or arena of 10,000 seats or more, gets applied to the new 250 seat First Baptist Church, increasing the cost of the fire alarm from $10,000 to $100,000, when a $3 light would do the job..

[Brad Weber]

Originally Posted by wogster

Part of the issue is that building codes are not always worded properly, for example a large place of assembly, where the legislators intended it to be applied to a stadium or arena of 10,000 seats or more, gets applied to the new 250 seat First Baptist Church, increasing the cost of the fire alarm from $10,000 to $100,000, when a $3 light would do the job..

Sorry to be blunt, but no, it wouldn't do the job, not even close.

Maybe if the operators were all specially trained and certified. If the light and control systems were proven to meet specific design and performance standards. If there were a way to confirm all aspects were always working properly and identify any faults. By that point you've probably spent a good part of what you might have saved.

At the same time, you can't use just any audio system for life safety, fire alarm and/or voice evacuation purposes. For an audio system to be used for such applications may require that all of the system components be approved for such use. The system would also typically have to be verified to meet all applicable life safety code requirements, which can include specific level, coverage, response and intelligibility requirements. And life safety, fire alarm and/or voice evacuation systems also typically have to be continually electronically monitored to verify that they are in proper operating condition and have to provide indication of any faults. All of these factors directly address the ability of the system to be relied on to function properly if ever needed, however when applied to typical live sound systems this can significantly affect the audio system and its cost.

As an example, some years ago I was designing an airport paging and announcement system and after seeing all the speakers wee were incorporating someone came up with the idea of using the same speakers for life safety. Their idea was to switch to dual coil speakers with one coil for the announcement/paging system and the other for life safety. With the products available and code in effect at that time we found that would have both negatively impacted the announcement/paging system and actually resulted in a net increase in cost.

I also know of one project where they did try to use an audio system for life safety and its not meeting the related performance requirements of the applicable code it was apparently one reason why the building was denied a Certificate of Occupancy. I would guess that the changes to that system, retrofit components, additional acoustical treatment, etc. required to make it compliant had a pretty high cost and that is not counting the rather large value lawsuits that I have been told were associated.

[cmchamp]

Flames off folks...
Code is code and needs to be complied with, or occupancy permits aren't given and money wasted.

[wogster]

Originally Posted by Brad Weber

Sorry to be blunt, but no, it wouldn't do the job, not even close.

Maybe if the operators were all specially trained and certified. If the light and control systems were proven to meet specific design and performance standards. If there were a way to confirm all aspects were always working properly and identify any faults. By that point you've probably spent a good part of what you might have saved.

At the same time, you can't use just any audio system for life safety, fire alarm and/or voice evacuation purposes. For an audio system to be used for such applications may require that all of the system components be approved for such use. The system would also typically have to be verified to meet all applicable life safety code requirements, which can include specific level, coverage, response and intelligibility requirements. And life safety, fire alarm and/or voice evacuation systems also typically have to be continually electronically monitored to verify that they are in proper operating condition and have to provide indication of any faults. All of these factors directly address the ability of the system to be relied on to function properly if ever needed, however when applied to typical live sound systems this can significantly affect the audio system and its cost.

As an example, some years ago I was designing an airport paging and announcement system and after seeing all the speakers wee were incorporating someone came up with the idea of using the same speakers for life safety. Their idea was to switch to dual coil speakers with one coil for the announcement/paging system and the other for life safety. With the products available and code in effect at that time we found that would have both negatively impacted the announcement/paging system and actually resulted in a net increase in cost.

I also know of one project where they did try to use an audio system for life safety and its not meeting the related performance requirements of the applicable code it was apparently one reason why the building was denied a Certificate of Occupancy. I would guess that the changes to that system, retrofit components, additional acoustical treatment, etc. required to make it compliant had a pretty high cost and that is not counting the rather large value lawsuits that I have been told were associated.

Okay Brad, you don't have to bite my head off....

However the requirements for a 200 seat church and the requirements for a 20,000 seat stadium may be different, probably should be different. However the way the AJH views the code and the legislators intended it to be viewed, may not be the same.