GFCI 2-wire Experiment

[FionaZuppa]

So what?

Nothing you have done has proved this:

it is exactly what i just proved.

i am somehow over-confident in my experiment, you seem to challenge it, please provide evidence from whatever experiment you do to prove me wrong.

I asked myself why you would think an 18k resistor in line with the hot and not across the two leads.

well, keep asking yourself this question until you understand why. lets start there.

 

[ATSman]

Me thinks someone here has been mixing something with the holiday Egg Nog :roll:

 

[K8MHZ]

my hi Z Fluje is blind to 18k resistor, how so, please enlighten us.

Easy enough to prove me wrong. Take it out and test again. You current will be a tiny bit higher, but not enough to make a difference because of the high resistance of the water. So, let's say you get 8 milliamps from hot and neutral through the water in an un grounded sink. Where is the danger? How would that current flow through a body if the body wasn't directly in contact with a conductor?

 

[FionaZuppa]

Easy enough to prove me wrong. Take it out and test again. You current will be a tiny bit higher, but not enough to make a difference because of the high resistance of the water. So, let's say you get 8 milliamps from hot and neutral through the water in an un grounded sink. Where is the danger? How would that current flow through a body if the body wasn't directly in contact with a conductor?

i dunno (well, i actually do know), how does my meter get amps (and voltage) reading via the meter probes in the water when the probes are not connected to anything ??

 

[K8MHZ]

Note that this GFCI has an EGC.

 

[K8MHZ]

I posted a similar video here years ago and the powers that be didn't like it and I got a de-merit. Hopefully, it won't be the case this time.

 

[K8MHZ]

i dunno (well, i actually do know), how does my meter get amps (and voltage) reading via the meter probes in the water when the probes are not connected to anything ??

Place a 3,000 ohm resistor across the leads (approx. value of human body) and see how many amps flow.

 

[FionaZuppa]

Note that this GFCI has an EGC.

i noted what he said, "...you can still get shocked...". did you note that too?
now, why dont you call him up and ask him to repeat the same experiment, but ask him to put both hands in the water (w/o touching anything) while a 2nd person drops the clock radio in. let us know what he says. he should be fine, yes??
:lol::lol::lol:

Place a 3,000 ohm resistor across the leads (approx. value of human body) and see how many amps flow.

now that would be dumb, yes? (dont answer, thats a dumb ask).
ask your Q a different way and i shall reply.

 

[zbang]

i am somehow over-confident in my experiment, you seem to challenge it, please provide evidence from whatever experiment you do to prove me wrong.

In normal scientific method and academic debate, the experimenter assumes they might have done something wrong and asks the other scientists to look for things they've missed. Their confident answers strengthen their position.

I'd like to see two things-
change the experiment to use an electrically isolated water bath (remove any possible influence of the drain, unless that's intentional)
a schematic of the experiment showing all possible current paths and the currents over them (measured or calculated); for this, I think sub-milliamp currents can be ignored (i.e. through air or a plastic tub)

Bonus points for including the conductivity of the water.

Also, since I'm being pedantic this morning , AFAICT this doesn't prove anything, but it does demonstrate an effect under certain conditions (as does the fish tank K8MHZ mentioned).

 

[K8MHZ]

i noted what he said, "...you can still get shocked...". did you note that too?
now, why dont you call him up and ask him to repeat the same experiment, but ask him to put both hands in the water (w/o touching anything) while a 2nd person drops the clock radio in. let us know what he says. he should be fine, yes??
:lol::lol::lol:

So why didn't the presence of the EGC in the GFCI make the GFCI trip? In the video, the EGC is useless. It failed to mitigate a hazard if there is still shock potential, did it not?

How did that happen?

 

[FionaZuppa]

In normal scientific method and academic debate, the experimenter assumes they might have done something wrong and asks the other scientists to look for things they've missed. Their confident answers strengthen their position.

I'd like to see two things-
change the experiment to use an electrically isolated water bath (remove any possible influence of the drain, unless that's intentional)
a schematic of the experiment showing all possible current paths and the currents over them (measured or calculated); for this, I think sub-milliamp currents can be ignored (i.e. through air or a plastic tub)

Bonus points for including the conductivity of the water.

Also, since I'm being pedantic this morning , AFAICT this doesn't prove anything, but it does demonstrate an effect under certain conditions (as does the fish tank K8MHZ mentioned).

1) the sink is isolated, all plastic tub, all plastic drain.
2) if you run the math from the provided data, the ohms of the water between the wire ends is roughly 2622 ohms. use the caliper pic to ascertain per-inch as you see fit.
3) the 18k i said, i actually said "~18k", which doesnt really matter what the actual ohms is if you understand why its there to start with
4) sub-mA cannot be ignored, at least not what my experiment proves
5) again, read the verbiage before pic #1, ask yourself, what is the most important/significant piece of info given?

So why didn't the presence of the EGC in the GFCI make the GFCI trip? In the video, the EGC is useless. It failed to mitigate a hazard if there is still shock potential, did it not?

How did that happen?

yep, thats what the video shows, but where is the actual hazard in that video?? i dunno, perhaps jump in and redo that experiment, yes? since you believe no amps will flow across water --> through you --> back to N then you should be excited to be the person they use for that experiment, yes? except, during take-2 w/ you in the water, keep the radio or dryer in off position before tossing it in :thumbsup:

 

[K8MHZ]

now that would be dumb, yes? (dont answer, thats a dumb ask).
ask your Q a different way and i shall reply.

The standard 'assumption' is that the human body presents about a 3k ohm impedance on it's surface, on average. That will allow 400mA to flow at 120 volts with no other source of resistance. 1000 ohms is sometimes used, but the point is, no matter what the impedance choice is, the current can be measured through a resistor of = value.

So, if you were to put a resistor of 3000 or 1000 or whatever in energized water, the amount of current flowing though it can easily be measured with a meter, and that resistor would reasonably substitute the impedance of the human body.

 

[K8MHZ]

yep, thats what the video shows, but where is the actual hazard in that video?? i dunno, perhaps jump in and redo that experiment, yes? since you believe no amps will flow across water --> through you --> back to N then you should be excited to be the person they use for that experiment, yes? except, during take-2 w/ you in the water, keep the radio or dryer in off position before tossing it in :thumbsup:

So, what is it? Is there no hazard, or is there a hazard and the properly grounded GFCI failed to mitigate it? You can't have it both ways.

 

[FionaZuppa]

The standard 'assumption' is that the human body presents about a 3k ohm impedance on it's surface, on average. That will allow 400mA to flow at 120 volts with no other source of resistance. 1000 ohms is sometimes used, but the point is, no matter what the impedance choice is, the current can be measured through a resistor of = value.

So, if you were to put a resistor of 3000 or 1000 or whatever in energized water, the amount of current flowing though it can easily be measured with a meter, and that resistor would reasonably substitute the impedance of the human body.

nice. so, take your #, and the # i posted for water ohms. the hazard can/may/possible/scenario present itself in such a way, that according to your #, could allow 21.7mA through the body. so knowing this is a real possible scenario, with countless other scenarios that would be less than 21.7mA, you still willing to be in that sink when Mr GFCI Testor drops the radio in ???

So, what is it? Is there no hazard, or is there a hazard and the properly grounded GFCI failed to mitigate it? You can't have it both ways.

are you really asking this Q this far in?? did you read ALL of post #1 ???

 

[K8MHZ]

In normal scientific method and academic debate, the experimenter assumes they might have done something wrong and asks the other scientists to look for things they've missed. Their confident answers strengthen their position.

I'd like to see two things-
change the experiment to use an electrically isolated water bath (remove any possible influence of the drain, unless that's intentional)
a schematic of the experiment showing all possible current paths and the currents over them (measured or calculated); for this, I think sub-milliamp currents can be ignored (i.e. through air or a plastic tub)

Bonus points for including the conductivity of the water.

Also, since I'm being pedantic this morning , AFAICT this doesn't prove anything, but it does demonstrate an effect under certain conditions (as does the fish tank K8MHZ mentioned).

I would also like to add that a concise hypothesis would be nice. What, exactly, is the experimenter trying to demonstrate? If the hypothesis is that a properly grounded GFCI is safer than a non-grounded one, I don't see how anything in the OP's experiment showed that. All it showed was what a meter read with probes placed in the water. That same meter will show 'ghost voltages' which is why I am suspect of the actual value of the readings due to the high Z meter being used.

 

[K8MHZ]

nice. so, take your #, and the # i posted for water ohms. the hazard can/may/possible/scenario present itself in such a way, that according to your #, could allow 21.7mA through the body. so knowing this is a real possible scenario, with countless other scenarios that would be less than 21.7mA, you still willing to be in that sink when Mr GFCI Testor drops the radio in ???


are you really asking this Q this far in?? did you read ALL of post #1 ???

Did you actually measure 21.7 mA by putting a resistor in place of the human body? Or are you just guessing?

 

[FionaZuppa]

I would also like to add that a concise hypothesis would be nice. What, exactly, is the experimenter trying to demonstrate? If the hypothesis is that a properly grounded GFCI is safer than a non-grounded one, I don't see how anything in the OP's experiment showed that. All it showed was what a meter read with probes placed in the water. That same meter will show 'ghost voltages' which is why I am suspect of the actual value of the readings due to the high Z meter being used.

yikes again. there are no "ghost" voltages in the water, its not a pool of liquid insulator. the 1st pic i posted is just showing the line voltage at the end of the wire, a basis for math calculations. in water, w/o a voltage src, the voltage gradient will be extremely small unless the pool of water is large and very electrolytic.

Did you actually measure 21.7 mA by putting a resistor in place of the human body? Or are you just guessing?

guessing?? no. your 3k + 2622 of the water = 5622ohm. my 122v/5622 = [YOU RUN THE MATH ON YOUR WIZZY-WIG DO-DAD]
one of many possible scenarios, could be more or less than this, but my wild crazy guess is, probably less mA than this in the distribution of scenarios.

 

[K8MHZ]

I don't understand why the OP is so reluctant to make some changes and give us the values. We are just supposed to make assumptions based upon a single (possibly flawed) experiment.

There really shouldn't be anything to hide.

 

[K8MHZ]

yikes again. there are no "ghost" voltages in the water, its not a pool of liquid insulator. the 1st pic i posted is just showing the line voltage at the end of the wire, a basis for math calculations. in water, w/o a voltage src, the voltage gradient will be extremely small unless the pool of water is large and very electrolytic.



guessing?? no. your 3k + 2622 of the water = 5622ohm. my 122v/5622 = [YOU RUN THE MATH ON YOUR WIZZY-WIG DO-DAD]
one of many possible scenarios, could be more or less than this, but my wild crazy guess is, probably less mA than this in the distribution of scenarios.

I don't doubt your math. I want to see what the meter will read.

 

[jim dungar]

you need to ask yourself, in all the text before 1st pic, what is the most important piece of information ???

Is the most important piece of information, that you believe you understand electricity, and GFCI's, better than most of the forum participants and moderators?