Bad idea to hang volume control boxes onto high voltage boxes? - AVS Forum
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post #1 of 11 Old 05-23-2013, 10:46 AM - Thread Starter
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I've seen all sorts of mention about keeping speaker wire away from high voltage wire whenever possible. On the other hand, I see many custom installs where speaker volume (WHA) is attached directly to high voltage boxes trimming out with double/tripple gang decora plates.

On my custom home build, I'm torn over the functional value of separation versus the esthetic value of combining. So, anyone want to chime in on how much interference, if any, really comes into play when together?

P.S. I found very nice "clip on" low voltage boxes that have tabs on the front and double sided tape on the side. Perfect alignment to get a multi-gang decora plate onto.

Thanks in advance!
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post #2 of 11 Old 05-23-2013, 04:12 PM
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It's fine if you do not run the wires directly with each other.

It's about keeping the wires at least 12 inches away from each other. Having them come together right at the end point, like at the volume control, is fine.
If you run the wires parallel to each other closely, you can pick up interference and there will be a buzzing sound coming from the speakers whether they are on or not.
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post #3 of 11 Old 05-28-2013, 12:43 PM
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First, passive speaker cables are basically immune to hum pickup from power lines. The impedance is too low. Now if these are low level audio signals, that is feeding an amplified speaker, then you must have separation.

So much for the engineering theory.

Now as for electrical code, you can't bundle low voltage wiring with high voltage. It's a fire and safety issue. And while you are allowed to have high voltage and low voltage in a gang box, you typically must install a barrier between the two sections. They sell these as well as special boxes with an isolated LV section.

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post #4 of 11 Old 05-28-2013, 03:29 PM
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+1 on the barrier
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post #5 of 11 Old 05-28-2013, 09:35 PM
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Quote:
Originally Posted by Glimmie View Post

...
Now as for electrical code, you can't bundle low voltage wiring with high voltage. It's a fire and safety issue...
Not strictly true. Code doesn't care what goes through a wire (or box or conduit) as long as all wires and devices have insulation rated for the highest voltage involved. Case in point: We have a building with fire doors held by 120 VAC electromagnets and their wiring runs in the same conduit as the 24 volt alarm input and output lines. This is possible because the barrier strips on the bells and detectors are rated 600 volt and all the wire in the conduit is THHN, a 600 volt rated wire.
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post #6 of 11 Old 05-28-2013, 10:16 PM
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I have used the clip and stick on attachment rings on lots of projects.

I find they work great for phone,cable, network, etc. However confirm you volume control / keypad will fit. That is where I have ran into trouble.

Thanks

Tyler
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post #7 of 11 Old 05-29-2013, 11:57 AM
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Quote:
Originally Posted by olyteddy View Post

Not strictly true. Code doesn't care what goes through a wire (or box or conduit) as long as all wires and devices have insulation rated for the highest voltage involved. Case in point: We have a building with fire doors held by 120 VAC electromagnets and their wiring runs in the same conduit as the 24 volt alarm input and output lines. This is possible because the barrier strips on the bells and detectors are rated 600 volt and all the wire in the conduit is THHN, a 600 volt rated wire.

Yes, that is an approved exception. Another exception is if the low voltage and high voltage share the same reference. For example if the low voltage common is tied to the high voltage common such as in some electronic dimmers. Still the insulation rating must be considered.

And then there are all the article 725 issues with insulation flammability that have nothing to do with the electrical aspects.

But this is not typical in most AV installations. I guess you could run speakers with THHN and legally share a conduit with high voltage but why?

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post #8 of 11 Old 05-29-2013, 07:49 PM
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Mostly you wouldn't. A situation where it would be handy though would be adding a speaker run to an outbuilding that is already served by a conduit. The main reason I brought it up was simply because your statement that it's against the code was incorrect.
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post #9 of 11 Old 05-30-2013, 12:13 AM
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Quote:
Originally Posted by olyteddy View Post

Mostly you wouldn't. A situation where it would be handy though would be adding a speaker run to an outbuilding that is already served by a conduit. The main reason I brought it up was simply because your statement that it's against the code was incorrect.

Well we also know the NEC is also just a guide. Local authorities have the ultimate say. They can adopt the NEC as is, relax it, or make it even more stringent in their locality.

For example Los Angeles city does not require riser rated CLR communications cable between floors in non plenum spaces. Yet the NEC does. I am talking high rise commercial too, not residential. The city of Burbank does not allow Romex period! The NEC of course does on residential codes.

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post #10 of 11 Old 06-02-2013, 12:32 PM
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Quote:
Originally Posted by Ranger519v View Post

I've seen all sorts of mention about keeping speaker wire away from high voltage wire whenever possible. On the other hand, I see many custom installs where speaker volume (WHA) is attached directly to high voltage boxes trimming out with double/tripple gang decora plates.

On my custom home build, I'm torn over the functional value of separation versus the esthetic value of combining. So, anyone want to chime in on how much interference, if any, really comes into play when together?

P.S. I found very nice "clip on" low voltage boxes that have tabs on the front and double sided tape on the side. Perfect alignment to get a multi-gang decora plate onto.

Thanks in advance!

Volume controls typically don't fit inside the "clip on" boxes you mention. They would be fine for coax and/or Cat5 terminations though.
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post #11 of 11 Old 06-02-2013, 03:18 PM
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Class 1 and class 2 wiring should NEVER be in the same conduit. They CAN be found in the same ENCLOSURE but with a metal barrier.
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