GFCI 2-wire Experiment

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Ingenieur said:
yes it does
with 6 mA flowing the Vdrop across it is ~ 0.0067 A x 18000 Ohm or 120 V
there is really no drop across the water
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it doesnt matter !!!

here, lets start with baby steps

1) amps are flowing through the amp probes that are unattached in the water
2) hmmm, #1 infers that there is a voltage gradient there
3) the end of the wire is not shorted together in the water, thus there must be a voltage gradient
4) the summation of amps of all paths in the water will be less than 122v/17968ohm (aka "short")
5) there are infinite voltage gradients in a liquid conductor

does this 4th grade math make sense?

the inline R is nothing more than a "nuisance factor" in the math. you can extrapolate back to actual #'s using math, thus the inline R is meaningless in the experiment.
 
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FionaZuppa said:
it doesnt matter !!!

here, lets start with baby steps

1) amps are flowing through the amp probes that are unattached in the water
2) hmmm, #1 infers that there is a voltage gradient there
3) the end of the wire is not shorted together in the water, thus there must be a voltage gradient
4) the summation of amps of all paths in the water will be less than 122v/17968ohm (aka "short")
5) there are infinite voltage gradients in a liquid conductor

does this 4th grade math make sense?

the inline R is nothing more than a "nuisance factor" in the math. you can extrapolate back to actual #'s using math, thus the inline R is meaningless in the experiment.
Click to expand...



Assuming the water is 18,000 ohms as well, the voltage between your loads will actually be 60 volts, not 120 volts. This lower voltage will result in a lower voltage gradients in your water.


https://swtc.edu/Ag_Power/electrical/lecture/series_circuits.htm
 
FionaZuppa said:
it doesnt matter !!!

here, lets start with baby steps

1) amps are flowing through the amp probes that are unattached in the water
2) hmmm, #1 infers that there is a voltage gradient there
3) the end of the wire is not shorted together in the water, thus there must be a voltage gradient
4) the summation of amps of all paths will be less than 122v/17968ohm
5) there are infinite voltage gradients in a liquid conductor

does this 4th grade math make sense?
Click to expand...

1) yes
2) no, Z could be 0, which in this case it is very close to, per your OWN numbers!
3) no, again, not if Z= 0, since V = I Z, you can have current I, but no V if Z = 0
4) what? shouldn't the I = V/(R water + 18k Ohm)? if R water = 0 then ALL current will be EQUAL to 122/18k Ohm (unless stray current thru ground)
5) yes (or some quantum limit), but only if the Vdrop across the water is NOT 0, in this case, dang near 0

no need for snark
 
mbrooke said:
Assuming the water is 18,000 ohms as well, the voltage between your loads will actually be 60 volts, not 120 volts. This lower voltage will result in a lower voltage gradients in your water.


https://swtc.edu/Ag_Power/electrical/lecture/series_circuits.htm
Click to expand...

did i post voltage gradients? who cares about voltage gradients, its the amps that kill you, yes?

Ingenieur said:
1) yes
2) no, Z could be 0, which in this case it is very close to, per your OWN numbers!
3) no, again, not if Z= 0, since V = I Z, you can have current I, but no V if Z = 0
4) what? shouldn't the I = V/(R water + 18k Ohm)? if R water = 0 then ALL current will be EQUAL to 122/18k Ohm (unless stray current thru ground)
5) yes (or some quantum limit), but only if the Vdrop across the water is NOT 0, in this case, dang near 0

no need for snark
Click to expand...
Z is not zero, how about that for a real statement. Z in the water cannot be zero (unless the ends of wire were shorted) !!
here's another crazy statement, R of the water is not zero !!
 
mbrooke said:
You posted current. The lower the voltage the less current will pass through any given resistance.
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right, i said nothing about voltage gradients, so your point is what? you are extrapolating a voltage differential from the measured amps? ok, sounds logical, just not sure why that may help.
 
FionaZuppa said:
right, i said nothing about voltage gradients, so your point is what? you are extrapolating a voltage differential from the measured amps? ok, sounds logical, just not sure why that may help.
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My point is that your resistor is causing a lower current reading then would take place in the real world.
 
FionaZuppa said:
did i post voltage gradients? who cares about voltage gradients, its the amps that kill you, yes?


Z is not zero, how about that for a real statement. Z in the water cannot be zero (unless the ends of wire were shorted) !!
here's another crazy statement, R of the water is not zero !!
Click to expand...


loop R = 123/6.7 = 18360 Ohm (average, confirmed by your readings, 6.6 or 6.8)
loop R = 18360 = R water + R limiting = R water + 18000
therefore R water = 360 Ohm
V drop across water = 360 x 0.0067 = 2.4 V
2.4 volts in the water, ~ 0 compared to source of 123
even less if you use the 6.8 mA

the R limiting makes ALL the difference
in a real scenario you would have 123 across the water, not 2.4 lol

2.4 V / 1000 Ohm person = 0.0024 mA
assuming all current flowed thru him
but if water is 360 and he is 1000 only 360/1360 x 2.4 = 0.635 mA would flow thru the dood, the balance (2.4 - 0.635) mA thru the water
 
mbrooke said:
My point is that your resistor is causing a lower current reading then would take place in the real world.
Click to expand...

ok, and thats an issue for math because why?? with or w/o the inline R you can use math to tell you what the actual #'s are. maybe you see that now. i had already extrapolated the amps # and found it to be 0.1543mA. but if you look back in post #1, finding actual was not what i was looking to get out of the experiment. it simply shows the hazard, in general terms, a class of hazard that has many technical scenarios of which some may be deadly.

Ingenieur said:
the R limiting makes ALL the difference
in a real scenario you would have 123 across the water, not 2.4 lol
Click to expand...
my expectations that some would catch on has failed me.
if you notice, i already found the R of the water, it to be roughly 2622 across the 0.285" gap/path !!
so, in your head, remove the inline 18k. now what are the amps flowing in the wire ??
hmmm, that seemed very ez, yes ??
put on your math thinking cap for just a minute, you can extrapolate the "no inline R" answer for everything else too.
 
FionaZuppa said:
ok, and thats an issue for math because why?? with or w/o the inline R you can use math to tell you what the actual #'s are. maybe you see that now. i had already extrapolated the amps # and found it to be 0.1543mA. but if you look back in post #1, finding actual was not what i was looking to get out of the experiment. it simply shows the hazard, in general terms, a class of hazard that has many technical scenarios of which some may be deadly.


my expectations that some would catch on has failed me.
if you notice, i already found the R of the water, it to be roughly 2622 across the 0.285" gap/path !!
so, in your head, remove the inline 18k. now what are the amps flowing in the wire ??
hmmm, that seemed very ez, yes ??
put on your math thinking cap for just a minute, you can extrapolate the "no inline R" answer for everything else too.
Click to expand...

it's not that others haven't caught on
it's that your premise and conclusions are faulty

the R of the water can't be 2600 Ohm if R limiting is 18000, V is 123 and measured I is 6.8 mA
impossible
 
FionaZuppa said:
ok, and thats an issue for math because why?? with or w/o the inline R you can use math to tell you what the actual #'s are. maybe you see that now. i had already extrapolated the amps # and found it to be 0.1543mA. but if you look back in post #1, finding actual was not what i was looking to get out of the experiment. it simply shows the hazard, in general terms, a class of hazard that has many technical scenarios of which some may be deadly.
Click to expand...

I mean I could (which I sense a discrepancy btw), but it only complicates your original point IMO because a real world scenario is being replicated to prove a point.

Look at it like this: when doing an experiment you want to remove as many variables as possible.




my expectations that some would catch on has failed me.
if you notice, i already found the R of the water, it to be roughly 2622 across the 0.285" gap/path !!
so, in your head, remove the inline 18k. now what are the amps flowing in the wire ??
hmmm, that seemed very ez, yes ??
put on your math thinking cap for just a minute, you can extrapolate the "no inline R" answer for everything else too.
Click to expand...



I understand you are trying to get us to think by adding curve balls which is in some ways is elegant, however it distracts us from your original point IMO.
 
In addition to plastic spoons, rubber gloves would be prudent too. Getting hit hand to hand while wet is seriously unpleasant at best.

FionaZuppa said:
did i post voltage gradients? who cares about voltage gradients, its the amps that kill you, yes?


Z is not zero, how about that for a real statement. Z in the water cannot be zero (unless the ends of wire were shorted) !!
here's another crazy statement, R of the water is not zero !!
Click to expand...

Voltage gradients are a big deal. Watch this video and the one that plays after:

https://www.youtube.com/watch?v=uCAgsKaA_YY


and ofc the water's resistance isnt zero; it's actually fairly high, higher for fresh water than salt, hence why fresh water is more dangerous: voltage gradients are greater.
 
Ingenieur said:
the R of the water can't be 2600 Ohm if R limiting is 18000, V is 123 and measured I is 6.8 mA
impossible
Click to expand...

ah, nice catch.

for clarity
R inline is ~18,115
amps of wire in water was 0.006601A (6.601mA)
this tells us the gap presented an additional ~518.54 ohms

does that change the experiment in your view?

JFletcher said:
In addition to plastic spoons, rubber gloves would be prudent too. Getting hit hand to hand while wet is seriously unpleasant at best.

and ofc the water's resistance isnt zero; it's actually fairly high, higher for fresh water than salt, hence why fresh water is more dangerous: voltage gradients are greater.
Click to expand...

i mentioned water quality in post #1. and yes, your point of getting hit with amps is exactly the point, in which OCPD and GFCI (in context of the experiment) would just laugh and watch you frizzle to death.
 
btw, if you want to convince us GFCIs are useless, an experiment (actual, not theoretical) like mbrooke posted many months back showing an instance of a failed (read: FAILED) GFCI still allowing current to pass would be much more convincing. In that, I believe the ungrounded contacts had welded together, so it tripped and reset by the buttons, but in a tripped state allowed current to pass. GFCIs are not failsafe, however they are hardly useless. Aside from possibly double insulation, GFCIs are probably the best safety item to protect the end user from shock that the electrical industry has seen to date.
 
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