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Old 03-17-2008, 07:46 AM   #1
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Just an electrical question.


I know enough about electricity to safely change a light bulb. At our church there is a hum in the sound system. The guys working on it were talking the other day. They were talking about removing the grounds from the main panel for the sound circuits, and attaching them to their own ground rod out side somewhere. Is this OK.

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Old 03-17-2008, 07:54 AM   #2
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They were talking about removing the grounds from the main panel for the sound circuits, and attaching them to their own ground rod out side somewhere. Is this OK.
ABSO-FREAKIN-LOUTELY NOT!

It's fools like that that get people killed!

A ground rod does NOT, repeat NOT, "provide" or create a ground as we know it. That is NOT it's purpose.

If they did as they propose, and there was a direct fault to "ground", all that would happen is the current would be sent into the ground. No breakers would trip. Only whatever was faulted would be live with voltage, the wire leading to the ground rod would be live with voltage and also the earth around the ground rod would be live for a short distance.

DO NOT let them do this!!!

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Old 03-17-2008, 10:57 AM   #3
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Just an electrical question.


I would suggest an isolation transformer. MUCH easier to install, safe, and will probably solve your problems.

http://www.elect-spec.com/isotran.htm
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Old 03-17-2008, 11:39 AM   #4
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Just an electrical question.


If your church installs a dedicated circuit and GFCI breaker back to the panel for just the sound system and it's done properly and to code, I would venture to say that dedicated circuit should eliminate the hum. I'm talking about a home run wiring job from the sound system back to the panel, not a dice 'n' splice. Absolutely nothing else goes onto that circuit or gets plugged into it.

Most of the time, things like fluorescent lights, plug-in fans, refrigerators, monitors, PC's, water coolers, etc. find themselves plugged in on the same circuit as the sound system is plugged into or connected to. Motors, ballasts, compressors, motherboards, drives, etc. can all create a hum. The new CFL's can occasionally become a nuisance in this regard.

Just thinking outside the box a bit here. But, to echo what the experts already stated, don't fool around with the ground in the panel.
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Old 03-17-2008, 11:58 AM   #5
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Just an electrical question.


FWIW, I suggested a GFCI breaker simply because some churches do have outside speakers connected onto their sound systems and will on occasion set up a podium and microphone outdoors. In the event of inclement weather, the GFCI breaker will afford some protection against a shock hazard. Lots of folks will either hold onto the microphone as they're speaking or touch it with their lips while singing into it. Just suggesting an inexpensive precaution.
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Old 03-17-2008, 12:26 PM   #6
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Just an electrical question.


I am curious as to how you think a GFI breaker will protect the secondary side of the sound system?
You do realize amplifiers have big transformers in them and nothing is line voltage. Speakers and mics are completely isolated from the line voltage portion of the wiring.

A GFI breaker in this application has NO safety benefit.
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Old 03-17-2008, 12:56 PM   #7
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I am curious as to how you think a GFI breaker will protect the secondary side of the sound system?
You do realize amplifiers have big transformers in them and nothing is line voltage. Speakers and mics are completely isolated from the line voltage portion of the wiring.

A GFI breaker in this application has NO safety benefit.
Perhaps installing a GFCI breaker is totally unnecessary as you suggest, Speedy Petey, but tell me, what harm would installing one do? Seems to me that it can't hurt anything or reduce the sound system's effectiveness. Musicians have been electrocuted - a few sadly killed - on stage during performances in freak accidents while simply touching a microphone or their electric guitar during inclement weather. Bad amp? Bad wiring? Despite one's best intentions, I have come to learn that poop does happen, especially when one least expects it.
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Old 03-17-2008, 01:34 PM   #8
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Just an electrical question.


No harm at all. You are totally correct. What was I thinking.
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Old 03-17-2008, 01:43 PM   #9
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Just an electrical question.


You whistling the Twilight Zone theme there, Petey?

Where in NY are you? I was born and raised in Brooklyn and lived there most of my life. Then to Queens, NJ, Westchester and now Arizona.
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Old 03-17-2008, 01:51 PM   #10
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Just an electrical question.


Upstate. South of Albany. Originally from the Island.
It's better up here.
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Old 03-17-2008, 02:39 PM   #11
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Just an electrical question.


Years ago, in another lifetime or so it seems now, I was in sales and travelled extensively by car, occasionally by plane.

I remember how beautiful it was up there - that is until the winter cold, snow and ice came along!!! One dark, bitter cold night after a brief snowfall earlier in the day, on my way back to my motel, I successfully managed to slide my company car downhill and around all the curves without incident. Even managed to eventually come to a full stop in the middle of an intersection, well past the STOP sign - until the wind picked up and my car started sliding on the ice! Back then, our company cars were outfitted with snow tires on them, no studs and no full chains.

If that car is somewhere around today, Petey, impressions of my fingers are probably still embedded in the steering wheel. Definitely NOT a "joy ride".
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Old 03-17-2008, 06:01 PM   #12
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Just an electrical question.


Quote:
Originally Posted by Dilligaf77 View Post
I know enough about electricity to safely change a light bulb. At our church there is a hum in the sound system. The guys working on it were talking the other day. They were talking about removing the grounds from the main panel for the sound circuits, and attaching them to their own ground rod out side somewhere. Is this OK.

Do NOT remove the ground rods or modifed the ground system at all.

really to be on safe side better off get a real electrician to come in and have them get the system up to date with it.

the reason why i say real electrician because we do work on some of compated system and we can able do it in safe manner instead some of the handyman do the work on the system.

[ don't get me wrong but in church that is not a very good place for handyman to mess aroudnd with the electrical system i treat them as a commercal location.]


Merci, Marc
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Old 03-17-2008, 06:11 PM   #13
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Just an electrical question.


You have a Ground Loop problem - You can get one of many ground isolating devices that are targeted at the audiphile set.

GFCIs could add hum rather than fix it.
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Old 03-17-2008, 06:37 PM   #14
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Just an electrical question.


What you have is a ground loop somewhere in your system, from experiece doing live sound this can be a quick fix or a big pain in the arse.

Trying make yourself a short mic cable(xlr) but don't connect the ground(which if memory serves me right is pin 1). Put this on the output of your mixer and then connect your main out into your adapter and see if that helps. You probably can buy one somewhere. Whatever you do never cut the ground pin off any of your equipment.

You can also buy an isoaltion transformer to put onto your audio line(same place the above adapter would go). Rapco makes one (http://www.rapco.com/Catalog2/blox.aspx#).

I would suggest trying to solve this as an audio problem first, probably will be alot cheaper then doing something with your power.

Only make changes to your power as a last resort.

Check out www.churchsoundcheck.com they have a great discussion group with proffesionals that will be able to give you some more info on this.

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Old 03-18-2008, 03:11 PM   #15
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Just an electrical question.


Hi All

Speedy. What the correct use for the ground rod?

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