Strange GFCI problem

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  #1  
Old 03-30-14, 01:32 PM
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Strange GFCI problem

My GFCI powers off whenever a high wattage appliance is plugged in, then it waits a minute or two and then powers back on. It continues powering on and off as long as the appliance is plugged in.

The GFCI itself never trips, just cycles off and on.
It does not have this problem with low wattage appliances (eg. clock, phone).

So, I installed a new GFCI ... but still have the same symptoms.
I disconnected the load wires and still have the same symptoms.

The circuit breaker connected to the GFCI has never tripped.

Anyone got any ideas?
 
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  #2  
Old 03-30-14, 01:46 PM
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A GFCI will not trip, and or turn back on due to overcurrent, but will only trip due to ground fault. There must be something in the appliance that is heating up and tripping an internal disk type interrupter, and when it cools down it comes back on. Plug your high wattage appliance and a lamp into the two receptacle plugs. See if the lamp goes out when the high wattage appliance cycles off. Let us know what happens.
 
  #3  
Old 03-30-14, 02:03 PM
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The same symptoms occur with coffee pot, toaster oven and rice cooker.
 
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Old 03-30-14, 02:20 PM
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What results do you have with the lamp plugged in the other half? Does the lamp go out when the appliance turns off?
 
  #5  
Old 03-30-14, 03:15 PM
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The green light on the GFCI is turning on and off. It is as if the voltage to the GFCI is intermittent, however, other appliances on the same circuit remain steady.
 
  #6  
Old 03-30-14, 03:51 PM
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Loose connection in the next outlet box upstream from the GFCI location?

Since you replaced the GFCI unit in question, I expect that you connected up the wires good and tight so the loose connection would not be at this GFCI.

The loose connection could have heated up in a fashion that contact was lost, then it cooled down in a fashion that contact was remade. By the way, loose connections heat up in general and become fire hazards.
 
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Old 03-30-14, 03:54 PM
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Do you have any receptacles on the same breaker upstream of the questionable GFCI? If so that is wrong if the questionable GFCI is connected to the load side of the other GFCI.
 
  #8  
Old 03-30-14, 03:57 PM
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If it is a small appliance circuit, there should be no receptacles upstream, but check anyway. A looseness upstream can cause problems downstream every time. Also check the connection at the breaker for looseness as well.
 
  #9  
Old 03-30-14, 04:10 PM
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I suspected upstream problem, so I plugged a digital clock (batteries removed) into an upstream receptacle.

If the power to that receptacle is interrupted, the clock display would start flashing.

Then I plugged the coffee pot into the GFCI and waited for it to start cycling on and off.

When the GFCI turned off, the digital clock remained on ... no problem.

I'm also thinking that if I call an electrician, he would be just as puzzled as I am.
 
  #10  
Old 03-30-14, 04:14 PM
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The power TO that receptacle may be just fine. What about the downstream from that receptacle to the GFCI?? You'll need to remove the power at the breaker and remove the receptacles to tighten the screws, or if they used stab backs, remove the wires to the screws to the side.
 
  #11  
Old 03-30-14, 05:05 PM
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Found it.

FOUND IT!!!

As you said, the supply to the upstream receptacle was okay, but the output had loose wires and charred insulation.

Because of all of your suggestions, I kept looking upstream until I found the problem. And it probably saved my house from catching fire.

Mucho thanks to all of you.

Hal
 
  #12  
Old 03-30-14, 05:34 PM
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Glad you got it. Thanks for letting us know. Just a bit of detail if this is a kitchen SBAC there should be only one GFCI and there should be no receptacles upstream of it.
 
  #13  
Old 03-31-14, 09:04 AM
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There are 2 receptacles upstream, but mostly unused. This house is 25 years old so possibly code has changed since it was built.
 
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