beef: volts don't kill, amps do

Discussion in 'General Electronics Chat' started by strantor, Apr 28, 2011.

  1. strantor

    Thread Starter AAC Fanatic!

    Oct 3, 2010
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    I've always been told that Volts don't kill you, Amps do. I have never quite accepted that explanation and I will tell you why, so you can correct me.

    They say that 4mA across your heart will kill you

    example #1: A tazer. They will tell you that a tazer will pass something like 50KV through your body but it doesn't put out enough amperage to kill you. What? It's a current limited voltage source, correct? So if your body's resistance is low enough to load the tazer past it's limit (assuming it's limit is somewhere below 4mA to make it nonlethal, shouldn't be too hard to load past that), then it's not putting out 50KV anymore.

    Example #2: A car battery. the battery in my truck can supply around 600amps at short, yet I can grab ahold of both terminals and not die. plenty of amps there, but they didn't kill me.

    The way I see it, in order to kill you, The voltage needs to be high enough to create a current above the 4 ma given the very high resistance of your body and the source needs to be able to maintain that voltage (in order to maintain that current) ,So it's a power thing and not solely an amperage thing, and a significantly high voltage needs to be involved.

    Now somebody please tell me where I am screwing this up.
     
  2. oidium45

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  3. retched

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    Lightning does not kill everyone it strikes. Nor do bullets.

    If you are sweaty enough, that battery terminal grab can have a different result.
     
  4. steveb

    Senior Member

    Jul 3, 2008
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    I think what you are describing here is the old problem that complex things can't be fully summarized by catchy phrases. The motivation behind the saying "amps kill and volts don't" is to stress the importance of caution when dealing with low voltages. Like you say, a car battery has the capability to kill because it can deliver plenty of amperage. Normally it's safe, but if you are wet, or have an exposed wound or decide to play around and do something really stupid, all bets are off and you may get killed.

    The quote is not really intended to stress that high voltage with a current limit is safe (or safer). Like you say, the protection mechanism automatically lowers the voltage to a safer level. So, high voltage is dangerous or even lethal because it will induce high current that will damage or kill you.

    Another subtle detail is the length of time that the current is applied. This also has an effect on that actual damage done.
     
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  5. t06afre

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    I think a car battery has to low voltage kill you even if you "peel" of the skin on both hands and touch the battery poles.
    However as hobbyist you should never exsperiment with any device that is meant to to zap or tease any living human or animal. And I also think the topic is to complex to debate here.
     
  6. bertus

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  7. GetDeviceInfo

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    Jun 7, 2009
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    or, your resistance is low. That's why electrocutions are typically associated with high moisture or high voltage.

    Which leads to the number one cause of injury, arc flash. Let two stout leads from that battery come together and the explosive reaction can lead to extensive injury, possibly death.
     
  8. atferrari

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    Have you noticed that the handbook shows 1 KHz and 3 KHz under "RF"?
     
  9. t06afre

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    I can also mention that surgons use a high frequency current to cut tissue during surgical procedures. This is named electro surgery. If you are interested you can find out more with Google
     
  10. beenthere

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    Apr 20, 2004
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