Strange GFCI testing issue


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Old 07-08-15, 07:36 PM
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Strange GFCI testing issue

Here is what I am running into installing GFCIs

When the outlet is tripped, the hot terminal still shows hot, however the GFCI in fact trips and whatever is plugged into it stops working.

Tester shows correct wiring, no open ground or neutral which was my first thought.

Here is the kicker - when I place my finger on the plastic part around the led light the issue goes away.

I have tested 4 different GFCIs and all are doing it. I installed them in a different location which is on a different circuit and they do not shows this issue.

Here are some pictures to give you a better idea of that the issue is. I am pretty stomped with this one. I am testing this on the main wire coming to the kitchen from the breaker box. No loose ground or neutral wires in the breaker box. My home was built in the 70's, Neutral wires and grounds are on the same bar, if that matters any.

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Last edited by defiance; 07-08-15 at 07:59 PM.
  #2  
Old 07-08-15, 08:12 PM
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Welcome to the forums.

I can't tell you how much confusion those non contact testers cause.

That tester works inductively. It picks up AC even when not actually touching a live wire. The non contact testers have only one purpose.... to warn you that you have live AC voltage in the area.

If you measured from the hot slot to ground or neutral you'd find 0v. Your finger is disturbing the inductive pickup pattern.
 
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Old 07-08-15, 09:50 PM
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Thanks for the welcome!

Using the multimeter to check hot to neutral I am reading 0v when tripped.

It just does not make sense to me that it is only happening on this circuit and not on the other 3 bathrooms with GFCIs. Be as it may, as you said, these testers are inductive and I use them as such to find wires behind walls. Just never had a similar issue, so it threw me for a loop.

Obviously the GFCI is working, I guess my OCD personality is just looking for an explanation to this anomaly. However, if there is not one and I do not have an actual electrical problem that needs to be addressed, I am happy with that.
 
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Old 07-09-15, 03:09 AM
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One thing to remember is the wiring is always hot, although the internal mechanism of the GFCI has tripped as it should have. Your tick tracer is picking up the induction from the nearby hot wire, as Pete mentioned. If it trips with the black button on your tester, or with the test button, it is doing its job. Now, if it weren't tripping normally, it could indicate the receptacle is wired incorrectly, ie, to the LOAD side rather than to the LINE side.
 
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Old 07-09-15, 07:23 AM
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Sometimes the non-contact testers are sensitive enough to pick up all sorts of stray electrical and magnetic fields in completely disconnected wires. Some people can even trip them by holding the tester up to the large veins in their neck. That type of tester is at best an early warning for when live power might be nearby. You always need to follow up with a definitive test using a probe tester like multimeter or neon bulb tester.
 
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Old 07-09-15, 07:30 AM
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Here is what I am running into installing GFCIs
Why did you buy 20 amp GFCI receptacles, you don't need them. All you need are 15 amp GFCI receptacles. I know, it's a 20 amp circuit, right? You still only need 15 amp GFCI devices, they are rated at 20 amp feed-through to continue the 20 amp circuit to the other 15 amp duplex receptacles which are also rated at 20 amp feed-through.

By the way, your first picture shows two test devices that are nearly worthless when it comes to troubleshooting. You wasted your money when buying them. They are both high volume and high margin items and the box stores sell millions of them.
 
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Old 07-10-15, 06:55 AM
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Sometimes the non-contact testers are sensitive enough to pick up all sorts of stray electrical and magnetic fields in completely disconnected wires
Try one under some high voltage power lines. That is one BIG magnetic field!
 
 

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