Gfci

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  #1  
Old 10-07-07, 11:11 AM
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Gfci

MY bathrooms outlets and lights are connected to a GFCI as required. I noticed while wiring in a new bathroom light over the sink that even though the switch controlling the light is off, that the GFCI will trip as I moved to the new fixture. I checked the voltages going to the fixture and all there is a small residual a/c voltage of 1-2 volts a/c. It seems to trip the breaker whenever i touch the white wire or ground it. Is this a normal occurance as the breaker seems to function correctly correctly whenever I am using the lights or outlets connected to this GFCI. Am I missing something????
 
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  #2  
Old 10-07-07, 12:13 PM
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Yes you did miss something. It is in electrical safety 101. Never work on an electrical circuit without first turning off power AT THE BREAKER PANEL.

If you had followed this step you never would have noticed the other glitch.

It looks like this circuit feeds more than one bathroom. Even though your switch was off to the light you were working on, the circiut was still live. When you shorted neutral to ground, you allowed current to flow back to the source that did not go through the sensor in the gfi breaker. (it followed the ground wire)

the GFI is designed to trip under this condition.
 
  #3  
Old 10-07-07, 12:23 PM
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Working on a live circuit in a residential environment is stupid. You risked death just to save turning off the breaker. There is no excuse for what you did.

Turn off the breaker before you work on this circuit again. As you have discovered, there may be power present whenever the breaker is turned on.
 
  #4  
Old 10-07-07, 12:38 PM
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Bottom line is the lighting is on the load side of the GFI, which is NOT code required BTW. Even though the switch was off the white is still connected to the GFI and as JW said, when you touch white to ground on the load side of a GFI it will trip. You did NOT trip a breaker. A GFI is NOT a "breaker".

Also, there was NO "residual" voltage. You were reading phantom voltage on your digital meter.

What the others is true. You have no idea what is connected to what and what is live when working like this.
 
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