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GFCI & FLUKE question


Scottpat
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Hi Scott,

Well, I don't have a fluke - mine's a Commercial Electric and it does not still sense something after the button has been tripped.

Weird story. Last week I was crawling through an attic when I spotted an old light fixture dangling by it's wires from the rafters. I took my sniffer and waved it near the old fixture. Sure enough, voltage. Then I followed the cable up over the rafter for about another foot - where it ended!

I was baffled. Couldn't figure out where it was sensing voltage. Then I saw it - a tiny little low-voltage doorbell wire nailed along the backside of the joist passing near the cut end of that cable.

Voltage induced Magnetic fields seem to work in very mysterious ways.

ONE TEAM - ONE FIGHT!!!

Mike

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Hi Scott,

Simple answer is no, meaning yes, it works for checking the outlet is off. The Fluke is not as sensitive (that's probably the wrong word) as some of the others. It also works very well for checking polarity on older two-prong outlets. Got mine at the local electrical contractor store for about $23 (There's also a 5-pack which brings the individual price down).

It will still show ungrounded fans, fridges, etc by touching the chasis, the only difference is that you need to actually touch the end to the testee rather than just getting close. No "client impressive" beeping but the lighted tip is easy to see in any light. After trying others, I highly recommend the Fluke.

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Originally posted by Scottpat

If a GFCI outlet is tripped, will a FLUKE voltage sniffer show that the outlet still has voltage from the current that is still at the connections on the back of the outlet?

I think I said that correctly!

I just tried my Fluke on a GFCI. When I tripped the circuit, the indicator light on the Fluke went out.

These are cool toys, but I wouldn't trust one in a critical situation.

For those who're interested, here's an explanation of how they work: http://www.ecmweb.com/mag/electric_know ... e_voltage/

- Jim Katen, Oregon

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At an inspection yesterday the Fluke was still glowing after the GFCI tripped. I thought that it could be a bad GFCI, but it happened on 4 other GFCI outlets as well.

On the back of the GFCI if the Load/Line are reversed wouldn't this cause the Fluke to still glow after the GFCI is tripped?

I could not get my SureTest to show anything after it tripped (showed everything OK before trip), and my multimeter was on the fritz(battery leaked inside the case).

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Originally posted by kurt

Tangent....

Can anyone explain why simply pressing the "test" button on the GFCI isn't an adequate test?

Is the Fluke deal TMI?

Kurt,

I have had GFCI outlet buttons trip when pushed but the outlets still remain live. I have also had outlets trip with the built-in button but not trip when tested with my equipment.

I don't know techincally why these conditions occur but I call it out as a problem that needs to be corrected by a licensed electrician.

Regards,

Steve

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Scott...

The Suretest will have no display for an open neutral. Is it possible that only the hot (not the neutrals) conductors were reversed? I believe that would result in an open neutral once the GFCI was tripped (but normal readings otherwise).

Hard to imagine they would do that at 4 GFCI's, but I guess if someone got it in their head that that was the way to hook them up...

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  • 3 weeks later...

The correcte way to test a GFI is a great debate on several forums. UL and the manufactures only recommend and acknowledge the "TEST" button.

UL link http://www.ul.com/consumers/groundfault.html

I use the 3 prong tester just like everyone else on newer homes. I made a testing board with multiple GFIs all wired incorrectly and let fellow inspectors use their 3 prong testers to try and find the incorrect wiring. Many of the defects can not be found with the 3 prong tester. The Ideal Sure Test was accurate every time.

Joe

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Originally posted by JoeMed

The correcte way to test a GFI is a great debate on several forums. UL and the manufactures only recommend and acknowledge the "TEST" button.

UL link http://www.ul.com/consumers/groundfault.html

I use the 3 prong tester just like everyone else on newer homes. I made a testing board with multiple GFIs all wired incorrectly and let fellow inspectors use their 3 prong testers to try and find the incorrect wiring. Many of the defects can not be found with the 3 prong tester. The Ideal Sure Test was accurate every time.

Joe

I'd like to hear more about this. Could you describe the "many" defects that a 3-prong tester would not find and that a Suretest would?

- Jim Katen, Oregon

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The limitations and missreadings come from incorrect grounding. If the neutral is jumped over to the ground, the 3 prong will respond "Correct Wiring", and will typically trip the device. No one was the wiser. OR The 3 prong could determine that the device "appeared to be" wired correctly but the device does not have a ground. Thus the tester would not trip the device, but the TEST button on the device did function.

The 3 prong tester is an indirect gross test of the GFI function buy diverting some of the curent to the ground. This is what makes the GFI circuit "unbalanced" and trip (sending power to the ground is not a controlled amount of voltage, like the required 4 mA to 6 mA to trip a device)

The sure test can determine, thru resistance, if the neutral is connected to the ground. It will also determine the amount of milliamps the device needed to trip. It will test the GFI if it is installed on an ungrounded system. The 3 prong will determine that it is ungrounded, but it needs a ground to function and test the GFI.

I hope this clarifies the limitations of the 3 prong tester.

Joe

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Originally posted by JoeMed

The limitations and missreadings come from incorrect grounding. If the neutral is jumped over to the ground, the 3 prong will respond "Correct Wiring", and will typically trip the device. No one was the wiser. OR The 3 prong could determine that the device "appeared to be" wired correctly but the device does not have a ground. Thus the tester would not trip the device, but the TEST button on the device did function.

The 3 prong tester is an indirect gross test of the GFI function buy diverting some of the curent to the ground. This is what makes the GFI circuit "unbalanced" and trip (sending power to the ground is not a controlled amount of voltage, like the required 4 mA to 6 mA to trip a device)

The sure test can determine, thru resistance, if the neutral is connected to the ground. It will also determine the amount of milliamps the device needed to trip. It will test the GFI if it is installed on an ungrounded system. The 3 prong will determine that it is ungrounded, but it needs a ground to function and test the GFI.

I hope this clarifies the limitations of the 3 prong tester.

Joe

Thanks, Joe, and welcome to TIJ.

I'll confess that my suretest sits in my bag almost exclusively these days.

Soooo, I'll ask you (and any other regular Suretest users), how often do you find bootleg grounds? (White wires connected to grounding wires in the receptacle box.)

During the couple of month period that I used the Suretest, I never found any.

- Jim Katen, Oregon

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Mine sits in the car, depending on the age of the house. 1975 is the mark that I pull it out and use it. Agreed boot leg connection is rare but I do find ungrounded systems with a ground at the receptacles? Some where is an accidental ground or an appliance that is connected and has a connection. These older systems are when I pull out the Sure-Test device. Yes, expensive and bulky, it doesn't fit into my pouch. Maybe next year I'll get the new smaller version.

Last week in the same house (5 years old) I found a GFI that only worked at the TEST button and another that did not work at the TEST button, but my "night-light" tripped it?? I asked the owner if they would give me the old devices to use as a sample testing for other inspectors.

Joe

thanks for the welcoming, nice forum. These sites are a wealth of information and experience.

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I assume you mean that you have access to the terminals at the back of the outlet. Of course the voltage is still there. The same as if you took the GFCI out of the circuit and tested the wires. If the circuit is fed from a GCFI circuit breaker there would be no voltage at any receptacle in the circuit when the CB has tripped.

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Originally posted by Trailblazer

I assume you mean that you have access to the terminals at the back of the outlet. Of course the voltage is still there. The same as if you took the GFCI out of the circuit and tested the wires. If the circuit is fed from a GCFI circuit breaker there would be no voltage at any receptacle in the circuit when the CB has tripped.

Scott knows that there's current at the back of the outlet. He's wondering if his volt stick will pick it up from the front of the outlet.

- Jim Katen, Oregon

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I've had it happen a couple of times since I started this thread, the last time(yesterday on new constriction) I removed the outlet from the wall and found the line/load connections were reversed. These were the older style GFCI's not the newer ones that will not reset if wired improperly.

I did an inspector No No and changed the connections and Voilà ! The volt stick did not light up this time when I placed it in the tripped outlet.

So my infield test show that a volt stick (I use the Fluke brand)will light up if it is inserted into a tripped GFCI outlet that has the line/load reversed. I also noticed that light on the volt stick was not as bright when the outlet was tripped compared to when it was not tripped.

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Jim,

I find bootleg grounds in 1 of 3 inspections I do. Make sure to read the manual that comes with the Sure test. If you are within 10 or 15 feet of the grounding rod it will show a false FG.

SteveR

Alert Inspection Service, Inc.

Sarasota, FL

I'll confess that my suretest sits in my bag almost exclusively these days.

Soooo, I'll ask you (and any other regular Suretest users), how often do you find bootleg grounds? (White wires connected to grounding wires in the receptacle box.)

During the couple of month period that I used the Suretest, I never found any.

- Jim Katen, Oregon

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Hi,

I've used the SureTest consistently for more than 5 years and wouldn't be without it. My first began smoking one afternoon six months into usage. I stopped using it and allowed it to cool down and it worked fine after that. Still, just to be safe, I contacted the manufacturer and they shipped me another overnight. The second hasn't had any problems except that the cord is finally starting to weaken at the cable to plug connection.

We've found false grounds in about 10 houses that weren't caused by proximity to the panel and were actually bootleg grounds in older houses done by owners. We routinely find open grounds in new construction that a 3-light doesn't seem to pick up for some reason, reversed polarity, open neutral or hot/grounds reversed, too high or too low voltage, and circuits with 4 or 5 times the amount of normally accepted voltage drop.

One house where several receptacles indicated hot/ground reversed took an electrician about 4 hours to figure out. Turns out the doorbell transformer had apparently been miswired and somehow had screwed things up. Not being an electrician, I don't really understand a whole lot about what the problem was, only that the SureTest identified it and I never got called on it or ended up paying for that electrician's time.

99.9% of the time the SureTest functions as an expensive 3-light tester. However, when it does spot stuff, it's usually the stuff that the cheap 3-light in my bag didn't pick up. So far, no electrician has ever challenged me on findings picked up by the ST.

In one house that I did for an electrician client, the ST indicated open grounds in about half the receptacled in an 11-year old home. The electrician thought the ST was wrong and asked me if I had a "real" outlet tester because he didn't believe the ST and wanted to check them himself. I handed him the cheap 3-light and told him to knock himself out. He checked those outlets and the 3-light indicated that every one of them was grounded. "See, I knew that thing couldn't be right with that many outlets ungrounded," he declared. I reached into my bag pulled out a screwdriver, handed it to him and said, "Your the electrician, let's confirm your findings," whereupon he removed a receptacle cover and found..........a clipped equipment grounding conductor. One after another he checked several more and found all of the EGC's clipped off (Who knows why?). After the 3rd or 4th receptacle he stopped and said, "Damn, I got to get me one of those," indicating the ST. I held up the ST and the 3-light tester and said, "This one (indicating the ST) costs about $400, this one (indicating the 3-light) about $6. Which one would you believe?"

Nope, I use it religiously. I know that most of the time it will find stuff that a 3-light should find, so maybe it is an expensive tool for the task, but I don't have any unreasonable expectations that it can perform miracles and I know that in all likelihood it won't miss the stuff that a 3-light will.

ONE TEAM - ONE FIGHT!!!

Mike

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I have used the Suretest since day one on every 3-prong receptacle I could get to in every home, bar one*, that I have inspected. If memory serves, I have found actual (confirmed) bootlegs in four older homes. My "lightly seasoned" opinion is that the first of those made the purchase and use worthwhile...the following ones were "gravy". Ungrounded outlets easily number in the hundreds, although I have no idea if the 3-light tester would have caught all of those.

The GFCI test is an added bonus. My procedure with GFCIs is the receptacle test button first and then retesting with the ST. I've had quite a few that tripped fine with the receptacle test button but wouldn't with the ST. One I remember regularly took 4500+ ms (4½ secs) to trip time after time. Would those GFCIs still protect the client? Maybe, but failing to respond to the ST in a "normal" fashion is, in my mind, an indication that they're no longer functioning as intended.

*The down side...I had to do one home using a three light tester because my original ST just quit working. Frankly, I felt kind of naked. So I bought and carry a back-up. Then Ideal Industries mis-shipped an extra unit (they told me to keep it for my troubles) so I now have three. I have returned three units for various reasons in three years, which is a pain. The cords also occasionally give me problems. Because of the above, I generally don't trust the first abnormal reading I get in a home and go back to the last "OK" outlet to check the unit. If I'm still in doubt I'll pull the back-up out of the bag. Even with all that, I still believe it's a good tool...it would just be nice if they were more rugged for HI use.

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