GFCI principals

[ryan_618]

I thought I knew pretty well how a GFCI worked...until last night.

Me and an instructor that I have known for a long while were doing a joint class last night and tonight, and he did an expirement. He took a hot and nuetral and inserted them into either end of a hot dog, to help simulate an electrical shock, and to demnostrate current flow. Oddly enough, it tripped when it was GFCI protected. Now, there were only two wires connected to the load, and there was not a parrellel path for neutral current to travel. I know that GFCI's measure current leaving against current returning via a CT, and if there is a difference of 4-6 mA it will open. According to Mr. Kirchoff, current leaving the power supply must be equal to current returning to the power supply.

Where did this leakage current come from and where is it going???

 

[al hildenbrand]

:wink: This goes to the smoke theory of electricity, and the sub-postulate involving steam releases. . . .the circuit is intact, and the current in equalling the current out, only as long as the smoke and steam don't escape the current path.

Seriously, though, how was the hotdog supported and displayed for the audience? Was there any chance of conductivity there? I imagine a fully insulated current path from the GFI to the end of the contacts inserted in the hotdog. . .

I can't imagine the hotdog as a voltage / current phase shifter or energy storage device.

 

[charlie b]

Was it a GFCI receptacle or breaker that tripped? I am wondering if the trip was a fault (high current going through the "load"), and not leakage current, that caused the trip.

Also, how did you turn the circuit on (switch, plug in, insert the second contact, etc.)? I am wondering if a high magnetic field might have been generated by the action of turning this circuit on, if the method of doing so was different than you usually see in household circuits.

 

[pierre]

If someone had bet me before the experiment, I would have bet that this would not trip the GFCI.

I cannot understand why it did, I am very curious to see if someone knows why it did.

My guess would be maybe the GFCI is malfunctioning... maybe not????

 

[macmikeman]

Ryan, I wouldn't have a clue why it tripped on this condition other than wrong gfi breaker. Try switching brands. How about since you have your rig set up, can you put an ark fault breaker on the hot dog tester and let us know how that works?. This begs for hot dog humor, but I will restrain myself. 8)

 

[steve66]

Seriously, though, how was the hotdog supported and displayed for the audience?

For some reason, I'm betting a bun was used to support and insulate the hot dog

But really, I think Charlie is probably on the right path. My guess would also be high current or a high magnetic field or rapid changes in current that fool the sensor.

By the way, if you do this to a potato, it glows. But don't use your wife's good silverware as electrodes.

Steve[/quote]

 

[don_resqcapt19]

Charlie,

I am wondering if the trip was a fault (high current going through the "load"), and not leakage current, that caused the trip.

I don't think the load current would be excessively high. In the past they sold devices to cook up to 6 hot dogs at a time using this method. We had one at home when I was a kid and it never tripped a breaker even when loaded with six hot dogs.
Don

 

[bphgravity]

I perform a lot of electrical experiments. Trust me, nothing works the way it suppose to. :twisted:

 

[ryan_618]

It's actually not my rig, although I think I will make one.

This particular setup was with a receptacle type GFCI. My freind had a plywood board with conductors stapled down to it, with slack near the ends of the black and white. The receptacle is switched with a single pole switch.

 

[charlie b]

Then do correctly I surmise that the hot dog itself was sitting on the plywood? That might be the answer to your leakage path. A GFCI can trip at 4 milliamps. With a 120 volt source, a leakage path with a resistance of 30,000 ohms or less would give you that much current.

 

[ryan_618]

Then do correctly I surmise that the hot dog itself was sitting on the plywood? That might be the answer to your leakage path. A GFCI can trip at 4 milliamps. With a 120 volt source, a leakage path with a resistance of 30,000 ohms or less would give you that much current.

Yes Charlie, I suppose you would be correct there. I shall talkl with my friend and see if he can elevate the hot dog into the air during the expirement.

 

[steve66]

I think we are back to my suggestion of insulating it with a bun

I wonder if the plywood was treated? A little salt and a little moisture makes a pretty good electrical path.

Steve

 

[luckyshadow]

Have your friend attach some plastic forks to the board then support the hotdog on the forks. Just a thought

 

[LarryFine]

When we executed, I mean electrocuted, hot dogs in science class, we placed a 100-watt bulb in series with the condemned. The bulb dimmed as the victim cooked.

 

[ryan_618]

Well, I just got done doing it at my house, and the GFCI held. I am thinking the one that was in use was either bad, or, as Charlie was wondering, maybe had leakage current through the wood.

 

[hockeyoligist2]

Dog

Dog

I don't think the load current would be excessively high. In the past they sold devices to cook up to 6 hot dogs at a time using this method. We had one at home when I was a kid and it never tripped a breaker even when loaded with six hot dogs.
Don

We had one of those cookers when I was growing up too. But we didn't have GFI's we had Edison's and Dad always kept extra pennies on top of the box!

 

[jmd445]

When I was a little younger (5th or 6th grade) I would do this to a hotdog for a quick snack when I came home from school. The only problem was that there was a black mark going through the hotdog and it didn't taste very good (ps: My father was an engineer-that explains a lot) :lol: .

 

[marinesgt0411]

the hotdog is just a resistor if it does not come in contact with anything else also make sure that your electrodes only touch the hotdog and not each other or anything else

check where the wires are stapled down

does your GFCI trip with a different type of load.

have used this type of hotdog cooker for a number of years have plugged it into GFCI Arc fault 15 amp 20 amp temporary or permanent power have plugged it into 120 volt 277 volt 240 volt whatever was available worked fine every time except if hotdog was in contact with something or if electrodes touched something