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Joined: Mar 2001
Posts: 2,056
R
Member
I have run into this situation with Home Inspectors for real-estate transactions.
They make a recommendation that a GFCI receptacle on an ungrounded circuit be grounded "in order for the GFCI to fuction properly".
It makes me want to scream.
I believe the ultimate test for the GFCI is the test button itself. It allows the test current to flow around the current sensor through a resistor, thereby creating a low-level imbalance between the 2 lines.
You'll have a hard time trying to convince some people who think they are "all that" with their little tester.
Bill,
This isn't necessarily simple, or safe but...
(Don't try this at home, kids)
On 2 occasions, I have taken an old line cord, jacket stripped about 12" and cut the neutral & ground at the jacket leaving 12" of (unstripped) hot lead.
After testing the GFCI with the button to verify it works, don gloves and drop the hot line into about 1" of water in the sink.
GFCI trips. Case closed. I'm a believer.

[This message has been edited by Redsy (edited 08-09-2002).]

Joined: Jul 2002
Posts: 74
S
Member
Have not tried it, but thought about it.Fill the basin with water and toss the the hair dryer in. See what happens!! Atleast we will know from a safety stand point if it really works, not just what a tester may or may not say. Seriuously, I have wondered the same. Had someone suggest jumping the ground of a gfci to the neutral, once again never tried it.

Joined: May 2002
Posts: 1,716
R
Member
Curt, This is exactly what I was pointing out. With out the EGC being present a typical analyzer will probably not work. The $100 Hubble variable level type or a iso tester such as Bio Tek makes would probably do the task.

Now, if in fact you need a conductor run from the neighbors house to test the GFCI, are we going to have it there when the actual event takes place?

This is my point, if it adds no more protection than any other two wire device, did the manufacturers push this requirement through?

Roger

Joined: May 2002
Posts: 1,716
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On the other hand, if we are to live and breath by the NEC, and the AHJ can't make his or her own rules, we are complying regardless of this situation . [Linked Image]

Roger

[This message has been edited by Roger (edited 08-09-2002).]

Joined: Nov 2000
Posts: 2,236
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Jumping the ground to the noodle would allow the "bug" testers to work, but would be a terrible idea otherwise.

Uh, wouldn't it?

Also, GFCI's are absolutely needed in the absense of a true EGC... They still work, they detect any "missing" current over 6mA regardless of where it's going. No GFCI will prevent a noodle to hot shock, even with an EGC. Unlike the AFCI issue, this is a non-issue. They save countless lives and are proven (and rather simple) technology.

Just my $0.02.



[This message has been edited by sparky66wv (edited 08-09-2002).]


-Virgil
Residential/Commercial Inspector
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I have to agree with Redsky. Push the test button, ckeck for voltage. I remember a thread here or on another forum not too long ago about this subject. Someone said that the test button was accepted as a satisfactory method of testing both by the manufacturers and by an organization which I can't remember, seems like it was NFPA or UL.

Joined: Oct 2000
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Virgil,

I don't think connecting the grounding pin to the Grounded conductor would make a GFCI trip. The fact that current is diverted away from the 'Neutral' is what makes it trip.

Paul,

Is there a way that, through electronic components, an imbalance can be simulated and still only use 2 conductors?

Bill


Bill
Joined: May 2002
Posts: 202
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hmm, isee $$$$ signs for the guy who can make a tester that you just plug in and it will test a 2 wire gfci. to the laboratory findo.

Joined: Aug 2001
Posts: 7,520
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Step #1. Stand in bath of water holding the hot wire from a long extension cord. #2. Have an assistant plug in extension cord. #3. If you're still reading this far, the GFI works. [Linked Image] But seriously.....

Virgil, temporarily linking the ground on the recept to the neutral wouldn't work, because the tester needs to divert current around the GFI to create an imbalance between hot and neutral. But as you said, you certainly wouldn't want to leave the jumper there.

If we were talking about a GFI recept rather than a GFI C/B at the panel, then you could temporarily jumper the recept ground to the supply-side neutral and the plug-in tester would work. But that's exactly what pressing the GFI's test button does, so why bother? All that the GFI test button does is connect a suitable value resistor from the load-side hot to the supply-side neutral (it would work the other way as well).

If an external test is really necessary, I think a long wander lead for the ground is the only practical (& safe) answer. Bear in mind that it wouldn't have to go to a grounding conductor or pipe etc. You could connect it to the neutral of a non-GFI'd circuit and it would work fine.

Bill,
I can't think of any practical way to set up an imbalance without having some other grounded reference point. With just two connections the current that comes out of one has to go back in the other, no matter what it goes through on the way. (That's why I can't figure how the "multicoupler" over on the other forum could have tripped the GFI).



[This message has been edited by pauluk (edited 08-10-2002).]

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The simplest method I can think of right off the top of my head would be to use a Wiggy and an extention cord.

Plug the extention cord into an outlet which is either ahead of the GFCI, or on the opposite Ungrounded Line Conductor [other "Phase"], then test with the Wiggy between one terminal of the GFCI ["Hot" or "Noodle"] and whatever terminal on the cord that gets a complete circuit going.
That's about the most simple and least hazardous method I can think of right now [you have my interest on this big time!].

Alternate method, of course, is to find some Grounded Metal item and clip a long test cable to it, just to drive an unbalanced current through the GFCI device.

Using the idea behind random nuiscance trips when starting some Cap Start Induction Motors [I have heard of this and read of this, but never experienced it!], maybe there's a way to draw an imbalance of current through the GFCI device [possibly via one or more recepts on the load side] using various Reactive components - such as Capacitors and Inductors, possibly with a Variable Cap [like a tuning Cap], or a Variable Inductor [a "Variac" might work] - or both!

Maybe even some form of Tank Circuit between the GFCI device and "Downstream" receptacles would be able to either push an imbalanced current on one circuit conductor, or draw an imbalance on one conductor.

Trying to get a current above 6ma to flow - and not setup a hazardous situation - is the biggest problem to deal with [IMHO].
I could draw an imbalance of microamperes easilly, possibly reaching upto the 1.0ma range, just by connecting certain components to a circuit, then driving the current into the earth [dirt] either by a direct dirt connection, or on a nice damp concrete slab. That's just not gonna cut the mustard, though! [where did that term come from???]

Going to do some thinking and maybe even some smoke testing on this over the weekend.

Scott S.E.T.


Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!
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