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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => Installed Sound/Contracting => Topic started by: Joseph D. Macry on July 31, 2013, 10:08:50 pm

Title: Move the rack *where*? Umm....
Post by: Joseph D. Macry on July 31, 2013, 10:08:50 pm
A church is repurposing a back room. They want me to relocate this rack to the floor right underneath the breaker box to the right. I warned them that the concentration of electrical circuits may cause interference with the audio electronics, especially the wireless mic receivers. They say go ahead and move it, then we'll see if there is a problem.
What do you think? Will they really see problems?
Title: Re: Move the rack *where*? Umm....
Post by: Ray Cerwinski on July 31, 2013, 11:02:31 pm
The most obvious problem is you will be violating the NEC by not keeping a minimum of 36" of clearance in front of that panel if you relocate the rack directly in front of it.

You also need to maintain a width of at least 30" left to right, or the width of the actual equipment (whichever is larger)
Title: Re: Move the rack *where*? Umm....
Post by: Joseph D. Macry on August 01, 2013, 12:05:13 am
The most obvious problem is you will be violating the NEC by not keeping a minimum of 36" of clearance in front of that panel if you relocate the rack directly in front of it.

You also need to maintain a width of at least 30" left to right, or the width of the actual equipment (whichever is larger)

Ray, the rack will sit underneath, not in front of nor beside. Breakers will still be easily reachable.
Title: Re: Move the rack *where*? Umm....
Post by: Mac Kerr on August 01, 2013, 12:10:48 am
Ray, the rack will sit underneath, not in front of nor beside. Breakers will still be easily reachable.

Underneath the panel on the floor does not allow a clear walking space in front of the box. The floor must be kept clear in front of the panel.

Mac
Title: Re: Move the rack *where*? Umm....
Post by: Brad Weber on August 01, 2013, 07:32:54 am
Ray, the rack will sit underneath, not in front of nor beside. Breakers will still be easily reachable.
As noted, "clearance" as used in the related sections of the NEC means the floor area being open.  Also, how do you envision addressing the audio cabling and power for the rack?  Is there a receptacle on the other wall that is not visible in the picture and is there sufficient cable length along with an acceptable associated path in order to get the cable to the proposed location?
Title: Re: Move the rack *where*? Umm....
Post by: Joseph D. Macry on August 01, 2013, 11:10:47 am
As noted, "clearance" as used in the related sections of the NEC means the floor area being open.  Also, how do you envision addressing the audio cabling and power for the rack?  Is there a receptacle on the other wall that is not visible in the picture and is there sufficient cable length along with an acceptable associated path in order to get the cable to the proposed location?

They are expecting me to extend cables (mic, speaker, power) from current location near rack, to the right, over the door and around. Yes, this would mean running all 3 types together along the wall and over the door.
The main thing is that they plan to knock a window in this wall to install organ pipes and windbox.

Can anyone get me a link to appropriate section of NEC code? (I'm about to google it in a minute.)
Title: Re: Move the rack *where*? Umm....
Post by: Joseph D. Macry on August 01, 2013, 11:23:53 am
Can anyone get me a link to appropriate section of NEC code? (I'm about to google it in a minute.)
Never mind, found the info, forwarded to client.
Title: Re: Move the rack *where*? Umm....
Post by: Brad Weber on August 01, 2013, 03:18:38 pm
The main thing is that they plan to knock a window in this wall to install organ pipes and windbox.
Do you mean an opening to the main space?  Do they have an Architect involved?  I recently ran into a similar situation on a project where the fire rated wall for an assembly space was the wall to the storage room and when we knocked a hole in that wall for a through-wall equipment rack they had to upgrade the storage room wall construction to provide the require fire rating.  I'd check to make sure they aren't potentially cutting a hole in a fire rated wall.
Title: Re: Move the rack *where*? Umm....
Post by: g'bye, Dick Rees on August 01, 2013, 03:40:12 pm
Ray, the rack will sit underneath, not in front of nor beside. Breakers will still be easily reachable.

You can't put it where they want it...period. 

They haven't a prayer...
Title: Re: Move the rack *where*? Umm....
Post by: Hal Bissinger/COMSYSTEC on August 01, 2013, 05:03:12 pm
What's it sitting on?? Looks like a storage bin.  ???
 
My first thought is to hang it on a wall someplace but I can't see what the rest of the room looks like or how big it is. You guys are right on about the NEC clearance violation of Art 110(26). 6.5 feet high from the floor, 30 inches wide and 3 feet in front.
 
-Hal
Title: Re: Move the rack *where*? Umm....
Post by: Joseph D. Macry on August 01, 2013, 05:39:23 pm
What's it sitting on?? Looks like a storage bin.  ???
 
My first thought is to hang it on a wall someplace but I can't see what the rest of the room looks like or how big it is. You guys are right on about the NEC clearance violation of Art 110(26). 6.5 feet high from the floor, 30 inches wide and 3 feet in front.
 
-Hal

We decided to place the rack on the floor about a foot to the right of the panel.
The rack is currently sitting on an empty rack box from a previous install. They say it can now sit on the floor. (It's a "set and forget" sort of system.)
The wall to the left is not fire rated. Note the wooden door which leads to the Sanctuary. Even if it was, I am not the guy cutting the window nor installing the organ parts. That is between the church and another contractor. My job, for now, is simply to move the rack out of the way.
Did you hear the one about the streaker who ran through the church? They caught him by the organ.....
Title: Re: Move the rack *where*? Umm....
Post by: Jason Lavoie on August 02, 2013, 01:22:15 pm
We decided to place the rack on the floor about a foot to the right of the panel.
The rack is currently sitting on an empty rack box from a previous install. They say it can now sit on the floor. (It's a "set and forget" sort of system.)
The wall to the left is not fire rated. Note the wooden door which leads to the Sanctuary. Even if it was, I am not the guy cutting the window nor installing the organ parts. That is between the church and another contractor. My job, for now, is simply to move the rack out of the way.
Did you hear the one about the streaker who ran through the church? They caught him by the organ.....

If they don't need to get at the rack then why not mount it up high instead of leaving it on the floor?
your wires have to go up to get around the door anyway.

Jason
Title: Re: Move the rack *where*? Umm....
Post by: Tim Padrick on August 04, 2013, 09:22:06 pm
Every now and then I get a big hum on vocal 1 or 2.  I go up on stage and sure enough, one of the musos has moved the mic offstage and put it in front of the breaker box.  Would I put a rack anywhere near a breaker box or disconnect?  Certainly not.  Then there's the code issues.
Title: Re: Move the rack *where*? Umm....
Post by: Ivan Beaver on August 04, 2013, 09:43:31 pm
Every now and then I get a big hum on vocal 1 or 2.  I go up on stage and sure enough, one of the musos has moved the mic offstage and put it in front of the breaker box.
If the mic is not being used-then it should be turned off.  How often does somebody sing next to the breaker panel anyway?
Title: Re: Move the rack *where*? Umm....
Post by: Joseph D. Macry on August 05, 2013, 11:32:03 am
If they don't need to get at the rack then why not mount it up high instead of leaving it on the floor?
your wires have to go up to get around the door anyway.

Jason

The existing rack is not a wall-mount model. The rector was perfectly happy with the rack sitting on the floor. He even asked me to not set it on the old, empty rack that was underneath, but set it directly on the carpet. They use this system in a "set-and-forget" fashion; all they do with the rack is turn it on and off. Yes, I ran wires up and over the door, and along the floorboards to the new rack location about 2 feet to the right of the breaker panel. No buzz or hum was detected on any channel including wireless mics.

They had also reported a "crackling noise" in the five ceiling speakers which are delayed in the rear of the sanctuary. I heard this noise as brief dropouts during loudest parts of speech. I found it coincided with the 70-volt amp (RDL model FP-PA35A) hitting the compressor circuit which kicks in 2db before peaking. RDL says the compressor should not be causing dropouts, yet it was. No way to defeat the compressor. So I lowered the gain on this amp, made it up by turning up the autoformer volume control on the back wall, and it worked much better.
Title: Re: Move the rack *where*? Umm....
Post by: Ivan Beaver on August 05, 2013, 12:32:24 pm


They had also reported a "crackling noise" in the five ceiling speakers which are delayed in the rear of the sanctuary. I heard this noise as brief dropouts during loudest parts of speech. I found it coincided with the 70-volt amp (RDL model FP-PA35A) hitting the compressor circuit which kicks in 2db before peaking. RDL says the compressor should not be causing dropouts, yet it was. No way to defeat the compressor. So I lowered the gain on this amp, made it up by turning up the autoformer volume control on the back wall, and it worked much better.
It could be that due to improper gain structure setup, the amp was being asked to do much more than it was expecting (could be the load is also to great for the amp-causing additional issues and the amp was simply "shutting down" to protect itself.  Not the amps fault.

But I could be wrong.  Very often the gear gets blamed-when it is actually the USER that is at fault-but it is MUCH easier to blame the gear.
Title: Re: Move the rack *where*? Umm....
Post by: Joseph D. Macry on August 06, 2013, 02:03:48 pm
It could be that due to improper gain structure setup, the amp was being asked to do much more than it was expecting (could be the load is also to great for the amp-causing additional issues and the amp was simply "shutting down" to protect itself.  Not the amps fault.

But I could be wrong.  Very often the gear gets blamed-when it is actually the USER that is at fault-but it is MUCH easier to blame the gear.

Ivan, I did explain the whole thing to RDL. 35 watt 70V amp driving 5 x 5 watt speakers via wall-mount volume knob. They said that regardless of the autoformer volume control setting, the compressor should be compressing, not dropping out. Still, we got it working well without hitting the compressor, and client declined to demand a replacement.
Title: Re: Move the rack *where*? Umm....
Post by: Hal Bissinger/COMSYSTEC on August 08, 2013, 05:07:46 pm
Don't know why you have a compressor just for that amp. (Do you?) The compressor should be for the entire system.
 
It does sound like that amp was going into protection. How did you determine your levels? Those LED indicators on the equipment aren't terribly accurate.
 
-Hal
Title: Re: Move the rack *where*? Umm....
Post by: Joseph D. Macry on August 09, 2013, 11:46:00 am
Don't know why you have a compressor just for that amp. (Do you?) The compressor should be for the entire system.
 
It does sound like that amp was going into protection. How did you determine your levels? Those LED indicators on the equipment aren't terribly accurate.
 
-Hal

This amp has a built-in compressor that kicks in at 2db before peak. There is no way to defeat it. It was not going into protect mode, as the drop-outs were only small fractions of a second long. It has thermal and short-circuit protection, not overload protection. I am convinced that this is a case of the compressor not working correctly. It's not a rack mount unit, but a small, back-o-the-rack block. Link to the amp: http://www.rdlnet.com/product.php?page=597
Title: Re: Move the rack *where*? Umm....
Post by: Hal Bissinger/COMSYSTEC on August 10, 2013, 01:51:46 pm
Not familiar with that amp. But if it were me I would put it on the bench with a signal generator, a scope and a dummy load and see what's really happening.
 
-Hal
Title: Re: Move the rack *where*? Umm....
Post by: Craig Hauber on August 25, 2013, 01:54:30 pm
A church is repurposing a back room. They want me to relocate this rack to the floor right underneath the breaker box to the right. I warned them that the concentration of electrical circuits may cause interference with the audio electronics, especially the wireless mic receivers. They say go ahead and move it, then we'll see if there is a problem.
What do you think? Will they really see problems?

Architecturally interesting how that door opens into the wall.  Goes against modern practice.  If the hinges were on the jamb in the corner instead then the wall between the open door and the panel would be a good place for a Middle-atlantic DWR-17.
That light switch is in a bad spot then.  wonder if that's why the door opens the wrong way.
(It is relatively easy to move the switch if there's a t-grid ceiling -same goes for all the rack wiring)
Title: Re: Move the rack *where*? Umm....
Post by: Hal Bissinger/COMSYSTEC on August 25, 2013, 04:15:02 pm
Architecturally interesting how that door opens into the wall.  Goes against modern practice.  If the hinges were on the jamb in the corner instead then the wall between the open door and the panel would be a good place for a Middle-atlantic DWR-17.
That light switch is in a bad spot then.  wonder if that's why the door opens the wrong way.
(It is relatively easy to move the switch if there's a t-grid ceiling -same goes for all the rack wiring)

That is interesting. Normally you don't install a door so that when you open it it can get in the way of things in the room. Proper way is to hand it so it opens against a wall like there is here. The switch is incidental, like the chicken and the egg, I think the door came first and at least somebody was thinking by not putting the switch behind the door.  :o
 
-Hal