Voltage on chasis

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  #1  
Old 07-26-05, 11:04 AM
bseyd
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Voltage on chasis

I was doing some work on a computer in my garage and noticed that when i touched the chasis I got a little tingle.

So I got out my multimeter and sure enough there was 38 to 40 votls AC between the netral and the chasis. Then I checked my work computer 10 feet away that was running and also got a tingle from the serial port on the back. What is cauing this? Is this just a result of ungrounded wiring. While my house has many 3 prong outlets none of them are correctly grounded. Isn't the neutral supossed to be at ground potential. I tried unplugging major appliances and nothing changed. I used to do electronic work but it has been a long time.

Any thoughts would be appreciated. (Other than call an electrician)

Thanks
 
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  #2  
Old 07-26-05, 11:27 AM
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The neutral of a circuit is a current carrying conductor. You will get a shock and could get killed from a neutral just like from a hot wire.

You should not have three prong receptacles in your house unless they are either properly grounded or protected by a GFCI. You should not be using a computer on a circuit unless it is properly grounded.

I suggest that you replace the ungrounded three prong receptacles.
 
  #3  
Old 07-26-05, 11:43 AM
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Originally Posted by bseyd
Is this just a result of ungrounded wiring. While my house has many 3 prong outlets none of them are correctly grounded.
Computer power supplies need a grounded outlet to work properly. Having three prong outlets without a ground is a code violation if not protected with GFCI and labeled with a "No Equipment Ground" sticker. Whether or not you created this problem, you should fix it by replacing the 3 prongers with 2 prongers, adding GFCI protection to the ungrounded circuits, or adding ground wires. The last option is very time consuming and must be done properly.

The computers should really have grounds.
 
  #4  
Old 07-26-05, 02:54 PM
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Because the chassis of the computer is isolated from ground (and really from everything else), you are probably getting a static charge, and measuring static voltage. Remember Van de Graaff generators that are used to entertain kids. You can get a tingle or zap from them, and you can read thousands of volts from them, but they won't kill you (usually).

But please ground your computer, not to a water pipe or a grounding rod, but to the electrical panel.
 
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