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  #1  
Old 07 December 2007, 10:07 PM
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Blow Your Top GFCI inventor tossed a toaster in the tub with his daughter

Comment: I have been told today that it is common knowledge that the inventor of
the GFCI receptacle had trouble selling his idea of decreasing deaths via
electric shock. As I was told today the inventor was passionate about his
new technology, but frustrated it wasnt selling. So, he put his daughter
in a bath tub, with investors looking on, put a plugged toaster in to the
tub to prove his product worked.
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  #2  
Old 08 December 2007, 03:53 AM
Bassist
 
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Are we then to believe that the increased sales of GFCI devices since this incident are merely to honor the inventor's late daughter?
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  #3  
Old 08 December 2007, 04:54 AM
ray2047 ray2047 is offline
 
 
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Electricity travels the shortest path. Shortest path would be within the toaster. Distilled water is a very poor conductor of electricity. If all of the drain and supply lines to the tub were PVC it would not be grounded. If the tub was fiberglass as is now common the tub would not have been conductive. Electric through the daughter would have been the least likely path.
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  #4  
Old 08 December 2007, 10:39 AM
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Quote:
Originally Posted by snopes View Post
Comment: I have been told today that it is common knowledge that the inventor of
the GFCI receptacle had trouble selling his idea of decreasing deaths via
electric shock. As I was told today the inventor was passionate about his
new technology, but frustrated it wasnt selling. So, he put his daughter
in a bath tub, with investors looking on, put a plugged toaster in to the
tub to prove his product worked.
You'll note that it says nothing about actually putting water in the tub...
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  #5  
Old 08 December 2007, 12:20 PM
Troberg Troberg is offline
 
 
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I don't know if he actally did it or not, but as long as the GFCI is working properly, it would be prefectly safe to take a bath with a toaster.

Even without such a device, it's probably safe anyway, as the short circuit will take place in the toaster or possibly between the toaster and the tub, not through the body of the bather. And I stand by that, even though Mythbusters arrived at a different result. Their experiment must have been flawed in some way, such as the measuring pads not being sealed watertight or something like that.
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  #6  
Old 08 December 2007, 01:13 PM
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But then humans aren't quite water tight either, the resistance of human skin is lowered when wet. Electricity doesn't take the shortest path, it takes every path, with due attention given to the resistance in that path. You may only get a fraction of the current, but that fraction may still be fatal.
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  #7  
Old 08 December 2007, 03:30 PM
Troberg Troberg is offline
 
 
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Quote:
But then humans aren't quite water tight either, the resistance of human skin is lowered when wet. Electricity doesn't take the shortest path, it takes every path, with due attention given to the resistance in that path. You may only get a fraction of the current, but that fraction may still be fatal.
Exactly, but since water is a crappy conductor, very little will go outside the toaster.

Too bad I don't want to ruin my toaster, or I'd made a try to see what happens. I'm that sure it's reasonably safe.
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  #8  
Old 08 December 2007, 05:34 PM
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Troberg, apparently you've never been jolted plugging a wet electrical plug into an outlet.
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  #9  
Old 08 December 2007, 06:21 PM
hevach
 
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Quote:
Originally Posted by ray2047 View Post
Electricity travels the shortest path. Shortest path would be within the toaster. Distilled water is a very poor conductor of electricity. If all of the drain and supply lines to the tub were PVC it would not be grounded. If the tub was fiberglass as is now common the tub would not have been conductive. Electric through the daughter would have been the least likely path.
Distilled water is a poor conductor, but tap water is generally not distilled. The harder the water, the more dissolved ions and the better it will conduct. GFCI's were invented in the 70's, so the norm would have been a tub with metal drains.

The Mythbusters' experiment was not flawed, the concept of shortest path is: Electricity follows the ENTIRE system. The shortest path will determine the amperage through any particular segment, but a major part of my later physics classes was determining the current, voltage, and resistance in complex systems with multiple paths for the current to follow. A short circuit will cause a reduced amperage through the correct path, not a complete stop. Most electronics simply wouldn't work if electricity worked in the simple way its explained in grade school.
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  #10  
Old 08 December 2007, 07:17 PM
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In the Mythbuster's test, didn't Buster only die when bath salts or urine were added to the tub? I thought he was fine in straight tap water.
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  #11  
Old 08 December 2007, 08:54 PM
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Charles Dalziel, UC's "In Memorium, 1986" (page 52)
Quote:
As a result of the dissemination of his research papers on electric shock, his services became in constant demand as a lecturer, as a member of commissions, and as a reviewer of specific cases of death or injury from electrical shock. From the reviews he came to realize that the commonest cause of such deaths came from ordinary household circuits under the malfunction known as “ground-fault.” His research objective then became to create a device which would interrupt a ground-fault current before it became large enough to cause human physiological damage. The sensitivity, speed of action, reliability, small size, and small cost required made the device almost impossible to design.

However, in 1965 Dalziel received a patent for a “ground-fault current interrupter” that would interrupt current before it grew to five-thousandths of an ampere and that was small, reliable, and inexpensive. The device was based on a magnetic circuit plus a then newly developed semiconductor device.

Subsequently, the National Electric Code was modified to require that this device be installed in electric circuits in all bathrooms, kitchens, swimming pools, and outdoor electric circuits in all new construction and extensive modifications of older constructions.
The article tells us he did have a daughter, Isabelle, but doesn't mention said experiment. IMHO, if the National Electric Code requires an invention to be in a healthy percentage of the outlets installed in new homes, I doubt investors would be reluctant to back it.
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  #12  
Old 08 December 2007, 09:40 PM
hevach
 
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Quote:
Originally Posted by geminilee View Post
In the Mythbuster's test, didn't Buster only die when bath salts or urine were added to the tub? I thought he was fine in straight tap water.
Only under their initial assumptions - it took salt added to give him an instantly fatal shock.

It was after filming that they did the scene at the end of that episode at the drawing board, there were two errors. For one, the resistance of ballistic gel was much higher than human flesh, so the shock measured was lower than a human would receive. Even ignoring that, the shocks with normal tap water were enough to cause loss of muscle control and damage to the heart and lung muscles - Adam mentions that they didn't take the effect of lower amperage into account before doing the test. This means that without help, a person in that situation was still in deadly danger, since they would have difficulty getting out of the tub.

Edit: http://www.fanpop.com/external/14845

From the Mythbusters results list - second one in the episode and was confirmed.
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  #13  
Old 09 December 2007, 06:13 AM
Troberg Troberg is offline
 
 
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Quote:
Troberg, apparently you've never been jolted plugging a wet electrical plug into an outlet.
The power has nowhere else to go in that case. In the bathtub, it has.
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  #14  
Old 09 December 2007, 06:30 PM
jimmy101_again jimmy101_again is offline
 
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Electricity flow is much more complex than most people think.

Like several folks have posted, current flows through all available paths, not through just the shortest path. Indeed, in all modern electrical devices current flow is never through the shortest path.

Tap water, even fairly hard tap water, has high resistance. The inside of a human is a much better conductor of electricity than is typical tap water since the concentration of dissolved salts in a person is fairly high.

As a result, current flowing through tap water plus a person in a tub will tend to flow preferentially through the lower resistance human than threw the water. The actual flow depends on the geometry of the situration and the resistance of human skin as well as the condcutivity of the water and the body.

Electrical shock in a human is most dangerous when the flow of current crosses the heart. A person can tolerate a very high energy shock between two fingers of one hand. The same shock between the person's two hands would be fatal.

It is true that most of the current flow will be via the fairly short path between condcutors within the toaster, but not all of the current will take that path. The typical 15 amp circuit found in most US homes will provide a brief pulse of current that can exceed 200 amps. Even if only a tiny fraction of that high current pulse passes across the persons heart it may be enough to stop the heart.

Back to the OP, I would think that it is highly unlikely that any knowlegable person would test a safety device in this manner. GFIs are very effective devices but they are hardly foolproof. Heck, they are supposed to be tested frequently because they do fail.
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  #15  
Old 10 December 2007, 08:25 AM
Troberg Troberg is offline
 
 
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Quote:
Back to the OP, I would think that it is highly unlikely that any knowlegable person would test a safety device in this manner. GFIs are very effective devices but they are hardly foolproof. Heck, they are supposed to be tested frequently because they do fail.
Yep. It would be a safe experiment if it works, but if the GFI is broken and fails, then there might be a danger, although I still doubt the bathtub danger, and am talking more in a general sense of the protection the GFI will give against electrical problems.
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  #16  
Old 11 December 2007, 02:58 AM
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In a more general sense, never rely on autmoatic protective actions to prevent a casualty that can be prevented through proper operator action: i.e. not throwing a toaster in the bath tub while you're in it.
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  #17  
Old 11 December 2007, 03:17 AM
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The OP story reminds me of some of the demonstrations that were done by Thomas Midgley. He supposedly demonstrated the safety of freon by breathing it in and exhaling it on a lit candle. No problem. 40 years later the same chemical was found to be destroying the Earth's protective ozone layer!
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