GFCI testing question.

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Yes it's bad, and the reason I don't trust the test button. There shouldn't be any voltage present on the wipers after the test button is depressed.
 
JohnJ0906 said:
The only test accepted by UL and the GFCI manufacturers is the test button. At least that is my understanding.

If you push the test button, and there is still voltage, the GFCI is bad.
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Exactly! And if you are an inspector you should be testing with the button and that's it. I have fought the "Battle of My tester dosen't trip the breaker you have to replace it" and it is very frustrating to say the least.

That battle actually was over an AFCI breaker but it is the same idea. Test button trips it, end of story.
 
Slater used to make this tool that would allow you to "dial in" a test current to see exactly when a GFCI would trip. It also has a receptacle on the top of the tester to test the leakage of an appliance. I use this quite a bit, and nobody's making anything similar nowadays that I know of.

gfcitesterfront.jpg
 
electricmanscott said:
Exactly! And if you are an inspector you should be testing with the button and that's it. I have fought the "Battle of My tester dosen't trip the breaker you have to replace it" and it is very frustrating to say the least.

That battle actually was over an AFCI breaker but it is the same idea. Test button trips it, end of story.
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I am not questioning the AFCI test. For an EI to come in and solely rely on the test button for the protection in question is pretty disturbing. I don't care if I please the EI in this matter. Above and beyond is where it's at for me:wink:

My real question remains at,... "Why do these testers look for ground when a GFCI was intended to work/trip to a fault on a two-wire circuit?
 
If the tester faults from hot to neutral, then you have a short circuit, not a ground fault - the GFCI isn't looking for that. So it has to do a hot to ground. If there is no EGC, then obviously, there won't be a ground fault. Where is this ground path coming from - it's only a hand-held tester.

On a no EGC circuit (2 - wire), use an extention cord from an outlet with an EGC, and use a wiggy tester from the outlet you are testing (hot) to the extention cord (EGC). Now you have a ground path, and the GFCI will trip.
 
"Why do these testers look for ground when a GFCI was intended to work/trip to a fault on a two-wire circuit?
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Because there is no other way to make a plug in GFCI tester work. I has to create leakage to ground to test the device and the only way to do that is to use the grounding socket on the receptacle. If there is no EGC, the tester cannot work.
Don
 
don_resqcapt19 said:
Because there is no other way to make a plug in GFCI tester work. I has to create leakage to ground to test the device and the only way to do that is to use the grounding socket on the receptacle. If there is no EGC, the tester cannot work.
Don
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What do you mean? A GFCI is, or at least thought it was, designed to look for an imbalance on the grounded leg. Are you saying I am wrong?
 
JohnJ0906 said:
If the tester faults from hot to neutral, then you have a short circuit, not a ground fault - the GFCI isn't looking for that. So it has to do a hot to ground. If there is no EGC, then obviously, there won't be a ground fault. Where is this ground path coming from - it's only a hand-held tester.

On a no EGC circuit (2 - wire), use an extention cord from an outlet with an EGC, and use a wiggy tester from the outlet you are testing (hot) to the extention cord (EGC). Now you have a ground path, and the GFCI will trip.
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Have you used these testers before? Why not fault from L-N? What I am asking, is this. GFCI's are intended to protect from line to grounded faults, why are these testers not? I can not seem to reply to this with the right words. Look at thee intended protection on two-wire and theory.
What am I missing?
 
76nemo said:
What do you mean? A GFCI is, or at least thought it was, designed to look for an imbalance on the grounded leg. Are you saying I am wrong?
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Your correct in your thinking, the problem is how would a two wire tester create that imbalance without the ground? Answer that question and you have your answer.
 
76nemo,
What do you mean? A GFCI is, or at least thought it was, designed to look for an imbalance on the grounded leg. Are you saying I am wrong?
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Yes I am...it is designed to look for a difference in the amount of current flowing on the ungrounded and grounded conductors of the circuit.
 
76nemo said:
What do you mean? A GFCI is, or at least thought it was, designed to look for an imbalance on the grounded leg. Are you saying I am wrong?
Click to expand...

A GFCI is looking for an imbalance between the ungrounded and grounded conductors. It does not require an EGC to do this The built-in test button does not require an EGC to properly test the GFCI. Plug-in testers do require the EGC to test the GFCI. Without an EGC, how can the plug-in tester create an imbalance?
 
JohnJ0906 said:
Without an EGC, how can the plug-in tester create an imbalance?
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They could make them out of metal, and require the operator to be bare-footed. ;)

I think many of us have hacked together a 2-prong GFCI tester by the addition of a long length of #14 stranded (soldered onto the former ground pin location inside the tester) and an alligator clip to attach to the nearest radiator pipe or water spiggot.
 
JohnJ0906 said:
A GFCI is looking for an imbalance between the ungrounded and grounded conductors. It does not require an EGC to do this The built-in test button does not require an EGC to properly test the GFCI. Plug-in testers do require the EGC to test the GFCI. Without an EGC, how can the plug-in tester create an imbalance?
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Beee-eye-N-Gee-Ohh, spells bingo. Why not have the ability to test two-wire?
 
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