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OT: Story about a guy killed demonstrating to kids how safe a 12v car battery is?

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  • OT: Story about a guy killed demonstrating to kids how safe a 12v car battery is?

    I remember this story, but can't find it using Google, all I get is stories of dead batteries. Am I misremembering?

    Thread on another site about electrocution, and I was wondering how the classic bathtub scenario actually works. Why does the current ground through the person in the bath rather than primarily just the water? Sure the person has electrolytes, but they're usually touching non-conductive porcelain, the grounding should occur through the pipes. And what if the the plumbing is all plastic, pex and pvc? How is it grounding at all if the water is off and the tub is plugged?
    Last edited by gellfex; 04-04-2021, 10:39 PM.
    Location: Jersey City NJ USA

  • #2
    Originally posted by gellfex View Post
    I remember this story, but can't find it using Google, all I get is stories of dead batteries. Am I misremembering?
    I imagine the header you have will get in the way..

    No one wants to see thah chit. I dont JR

    I guess I have to explain.. Ok

    This is the "Header" I spoke of. Is it odd or not? I thought it was, thats why I said something. JR

    "OT: Story about a guy killed demonstrating to kids how safe a 12v car battery is?"

    Last edited by JRouche; 04-04-2021, 10:56 PM.
    My old yahoo group. Bridgeport Mill Group

    https://groups.yahoo.com/neo/groups/...port_mill/info

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    • #3
      depends which story (theory) you looking for.
      one says amps kill, not volts
      other one says volts kill, not amps.
      The car battery would be all amps and low volts
      The hair dryer in the bathtub would be volts over low amps.
      If you've ever seen a wrench dropped across the terminals of a car battery, it could hardly be called 'safe'

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      • #4
        Volt's are what can stop (or re-start) your heart,,, as a mechanic holding on to ground with one hand and getting blasted in the other hand with 45,000 ignition volts and the path going right through the chest is not a good thing and yeah guys have died that way,,,

        Amp's as in a 12 volt car battery with tons of amps can blast hot molten lead and wrench material into your face and eyes, but as far as I know pretty harmless to grab with your hands or id be dead about a thousand times over by now...

        Didn't some inmate cheat the electric chair by dehydrating himself weeks before his "big day" ? that had more to do with volts but im sure they had some amperage to go along with it just to seal the deal...
        Last edited by A.K. Boomer; 04-04-2021, 11:02 PM.

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        • #5
          It's power that kills- and power is current times voltage. But current requires enough voltage to push that current through the resistance. 12 volts generally isn't enough to push current through skin- not enough to upset your bioelectrics anyway. But try applying it to a cut- yes, 12 volts can kill you. Most likely though, it will be heat and sparks that will cause you to react violently, and you'll be killed by bashing your head into a sharp thing under the hood, or you'll fall off the ladder, or into running machinery.

          If you get hit by lightning, there is enough voltage to establish a current path, and there is enough current in a lightning bolt to cause you great damage. But walk across a carpet and touch something- you'll get a jolt, but the charge is so low that it might only last a microsecond. That doesn't represent much power at all. In certain sensitive people it might stop your heart- you then die from lack of oxygen to the brain, but not from the shock itself.
          I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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          • #6
            Originally posted by gellfex View Post
            I remember this story, but can't find it using Google, all I get is stories of dead batteries. Am I misremembering?

            Thread on another site about electrocution, and I was wondering how the classic bathtub scenario actually works. Why does the current ground through the person in the bath rather than primarily just the water? Sure the person has electrolytes, but they're usually touching non-conductive porcelain, the grounding should occur through the pipes. And what if the the plumbing is all plastic, pex and pvc? How is it grounding at all if the water is off and the tub is plugged?
            Is this question related to the story about the wife borrowing tools? Do you want to make it look like an accident?
            Location: The Black Forest in Germany

            How to become a millionaire: Start out with 10 million and take up machining as a hobby!

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            • #7
              Originally posted by Black Forest View Post

              Is this question related to the story about the wife borrowing tools? Do you want to make it look like an accident?
              Only time the wife borrowed tools was when she grabbed granddad's planishing hammer to smash open rocks with the kids. Took one of the only unhardened hammers because it looked the crappiest! But no, she's a saint, perish the thought.
              Location: Jersey City NJ USA

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              • #8
                Back when I was an apprentice at Line School in about 1975 or so, one of our instructors was telling us about how little it takes to electrocute a person if the circumstances are "just right" and he told us about a farmer that they believe electrocuted himself trying to boost his combine's battery. Apparently he hooked both ends up to his truck battery and then crawled under the old self propelled combine to hook them onto the combine's battery. What they believe happened then is he took hold of both clamps, one in each hand, and squeezed them hard in order to open them so he could put them on the battery terminals. The believe because it was such a hot day and he was sweating, plus the fact the jumpers were old and the insulation was mostly gone on the clamps that his squeezing them was enough to lower the resistance in his hands to the point current flowed and stopped his heart.

                Normally you would expect the farmer to have had a heart attack, but apparently the autopsy ruled that out. There was zero reason for our instructor to BS us about this because if you start to BS about one thing, you lose credibility about other things and when you are an instructor talking about safety around power lines, a lack of credibility is the last thing anyone needs.
                Location: Saskatoon, Saskatchewan, Canada

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                • #9
                  Darryl, its the amps the kill, of course we can't escape ohms law so for a given resistance at so many amps we know the voltage so there is a power calculation to be had. I'd thought the common view was you'd need over 24V to put through enough amps given the average persons resistance (just measure yours). 12V can melt lead or make a big spark....because you're closing the circuit through metals which have much lower resistance so the 12V cause a lot of current to flow....not the same connecting through the body. Its also going to make a difference where and how good the connection is, e.g. hand to hand would offer more resistance (and less current) than chest and back (with the heart in the middle). Directly to the heart, 10 milliamps can kill.

                  From ohio state U physics dept

                  As the current approaches 100 milliamps, ventricular fibrillation of the heart occurs - an uncoordinated twitching of the walls of the heart's ventricles which results in death. Above 200 milliamps, the muscular contractions are so severe that the heart is forcibly clamped during the shock.
                  I wonder how universal that is, I suspect its a direct nerve and muscle contraction thing...but maybe there is variance with people or other health issues affect things and might make them susceptible at a lower voltage?
                  Last edited by Mcgyver; 04-05-2021, 09:23 AM.
                  in Toronto Ontario - where are you?

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                  • #10
                    I can’t see a 12v car battery killing you. Sure, it has the amps....but 12 volts. Just doesn’t have enough voltage to push those amps into the body in my opinion.

                    There’s a whole lot of people out there every day working on cars and we just don’t hear about any accidents at all when there’s a 12 volt circuit involved. I spent the better part of my 60 years working on cars and I don’t even remember feeling a light shock while working on cars....let alone getting a jolt enough to kill me.
                    Even with welders which run around 30 - 40 volts...I barely feel a shock.
                    Last edited by Tim9lives; 04-05-2021, 08:32 AM.

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                    • #11
                      I went to High School with a kid who decided to change his non-sealed battery while smoking a cigarette (this was in the late 70s). He wasn't injured but there were no eyebrows or bangs for a couple if weeks.

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                      • #12
                        Electricians are very conscious not to put themselves in the path to ground especially if the path is through their chest.

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                        • #13
                          It takes a LOT less than 100 mA, but it has to be applied to the heart itself.

                          All the arguments about how much current it takes are kinda stupid, actually. The variance of current is because a person has a fairly large cross-section, and the conductivity varies across that. So "how much current it takes to kill you" is really "how much current through the body it takes to get sufficient current through the heart".

                          The heart will be affected by a very small amount of current, micro-amps, if it goes directly through the heart. Muscles are electrically activated, and both the voltage and current involved are small. It can take a very small amount of current to induce fibrillation and stop effective pumping. But getting that much current fairly deep inside the body takes more current total, in most cases.

                          The high voltage "defibrillator" is applied directly over the heart, and relies on a high voltage pulse of current to reach the heart with some of it.

                          The body is all conductive, and you need to have enough current through a particular part of that conductive body to electrocute someone.
                          Last edited by J Tiers; 04-05-2021, 09:41 AM.
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                          • #14
                            If someone told me a person had been killed by a car battery my natural tendency would be to assume the battery exploded.
                            Mike
                            Central Ohio, USA

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                            • #15
                              I always cried foul when Rambo was tied to a chair and the bad guys had the jumper cables and was making sparks with them and everybody's eyes got
                              big out of fear. But the movie industry does have a lot of people believing this.
                              John Titor, when are you.

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