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First of all, I am no electrician.
I’ve found a problem in my home that I was not aware of before. In one of my rooms (that I just began using as an amature recording studio), I sometimes get a very small “continuous” shock when touching the strings of an electric guitar and microphone. I didn’t notice the problem until playing with no shoes on (obviously, I became the easiest path to ground). I became very worried when a friend was working on my computer, and found that the CPU casing was “hot”. The kicker is that it doesn’t always happen.
I’ve checked all the outlets and switches, and they seem to be grounded correctly. I know the wiring is in good shape because I replaced the drywall last year, and took care to look for anything that might need to be replaced. The main house has old aluminum wiring, but this room was an addition (70’s I think) and is wired with copper romex.
How do I troubleshoot this problem…or should I just call an electrician?
Replies
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It sounds like it could be a hot neutral, which can be checked with a plug-in tester. But, yes, you should call an electrician for the find and fix.
Jeff
*b CALL AN ELECTRICIAN!!!!! TODAY!!!!
*To me it sounds more like a floating ground, which due to capacitance will tend to float to about half the line voltage, but at an extremely high impedance.What I'd do -- and of course you should call the electrician instead -- is get a VOM, a 15 watt light, and a long clip lead. Run the clip lead from a known good ground, maybe even at the service entrance, to the room with the problem. First measure voltages between the known good clip lead ground and the hot, neutral, and ground in the room. If things were OK, hot would be hot, and the rest would not. But you'll probably find something different. In that case, connect the light bulb in parallel with the meter, and check again. If the hot ground is floating, it'll test hot with the meter, but not when the load of the bulb is present. If the ground is not just floating, but actually connected to the hot, the bulb will light up. Anyhow, that's what I'd do. You, however, should call an electrician so I don't get flamed for this post. ;-)-- J.S.
*Definitely get an electrician to check the problem out. As an aside, this is not an uncommon problem in the music and theater world. It's also potentially deadly. Part of the problem is that with a guitar, you are the ground. If you open up the guitar, you'll likely find a ground wire attached to the bridge. I don't recall specifically which one, but in one of the guitar electronics reference books, there is a schematic for a resistor/capacitor add-on that will limit the voltage that can leak through. I've added this circuit to all my guitars. I can't recall, but the book may have been by Craig Anderton, or Adrain Legg. It's been a while since I've referred to it. It should be commonly available in music shops and book stores.Mike
*Thanks all for the input...sounds like I should just call an electrician, since it isn't one of my strong suits.The thing that really throws me though, is the fact that the problem doen't always occur. I am sitting in that very room right now, and I just tested the microphone (which delivers the same shock as the guitar) and...nothing. I certainly don't understand everything John posted (which is why I should just call an electrician), but what would make the problem "come and go"? Just seems that the answer is in that small fact somehow.Obviously it's driving me nuts, since I'm sitting here at midnight.Thanks again, and if anyone can can explain the inconsistency, it sure would help me sleep.
*Like Jeff said....You can buy an inexpensive plug in tester to see if you have a hot and neutral reversed in one of your outlets.
*If you are plugged into a vintage Supro amp, thats what the problem is. Probably not in the house wiring, average street electrician won't know what to do. Do you have any intentional ground lifts going?
*What is plugged in when you have the problem, that is not plugged in when you don't have the problem ?
*If you are are bonafide audiophile and are using a vintage tube amplifier, with a 2 prong plug, you are experiencing what I found out when I was 10. An electrician will be of absolutely no help. Older equipment often had a 0.02 microfarad capacitor connected from one side of the power cord to chassis to help keep hum from 60 Hz (them cps) to an acceptable level. This capacitor allows a small non-lethal 60 Hz current to flow to anyone who is in contact with the chassis with bare feet, but only when the power cord is installed 1 of 2 directions in the outlet. If this is the case, you can easily fix it by adding a polarized plug (one prong wider) to your amp.
*PS: If you are serious about your amateur studio, consider adding an isolation transformer with a center tap ground(vs the white wire)to eliminate any hum or noise you get.
*'sounds like you have an open or near-open neutral. So return current is trying to get back to the panel bus bar through the ground system - the green wire ground, anything grounded, or you (I'm guessing your floor in this room is concrete).If the breaker on this circuit was GFCI (which it should be on a concrete floor), it would trip.The wiring may be new in the addition, but is it spliced into the existing AL in the house? It's pretty common for the resistance in older AL connections to go high. 'can be dangerous; wires heat up, insulation melts, etc. Or just the shock hazard associated with a bad neutral.This is a potentially dangerous situation; best to call in a pro.
*Now that you mention it Art B, I can remember getting mild shocks off my Fender guitar/Bandmaster amp combination back in '71-73 when playing in bare feet.But his CPU chassis is 'hot' too ....Jeff
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First of all, I am no electrician.
I've found a problem in my home that I was not aware of before. In one of my rooms (that I just began using as an amature recording studio), I sometimes get a very small "continuous" shock when touching the strings of an electric guitar and microphone. I didn't notice the problem until playing with no shoes on (obviously, I became the easiest path to ground). I became very worried when a friend was working on my computer, and found that the CPU casing was "hot". The kicker is that it doesn't always happen.
I've checked all the outlets and switches, and they seem to be grounded correctly. I know the wiring is in good shape because I replaced the drywall last year, and took care to look for anything that might need to be replaced. The main house has old aluminum wiring, but this room was an addition (70's I think) and is wired with copper romex.
How do I troubleshoot this problem...or should I just call an electrician?