Electric Shock

Discussion in 'General Electronics Chat' started by tahir51214, May 11, 2013.

  1. tahir51214

    Thread Starter New Member

    Nov 11, 2011
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    In which case intensity of shock will be most severe to a person 400v, 1A or 200v, 2A or 12v, 2.5A..
    Time for all shocks remains same?
     
  2. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    Death can be more or less severe?

    only 100 mA are required for death(heart stoppage) to occur in most people.

    12 volts is usually not enough to shock since the skins resistance prevents current flow at that voltage level, unless a liquid electrolyte like water is present in abundance.

    Also the path which the current takes is very important. If the voltage enters at the hand and leaves by the feet, then great harm can be done. Whereas, if the voltage enters and leaves by the same hand(through the fingers) the damage, and risk of death, is greatly reduced.

    Planning on torturing something?
     
  3. tahir51214

    Thread Starter New Member

    Nov 11, 2011
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    Actully I still dont know is it power that causes shock or voltage or current?
    Im asking just for info. I have a lab and I dont work on voltages more than 12V.
     
  4. russ_hensel

    Well-Known Member

    Jan 11, 2009
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    Current is normally the killer in shocks. Voltage is not important except that ohms law often applies, skin resistance is usually fairly high so voltages under 30 v are usually considered safe. In any case dry skin is safer than wet so only work with dry hands. In some cases if the shock is just in a limb then the power can cause heating and burns, sometimes quite severe. A bit off the point but this may amuse: http://www.youtube.com/watch?v=9tzga6qAaBA
     
  5. t06afre

    AAC Fanatic!

    May 11, 2009
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    This question is not very, shall we say realistic. The person behind this question can not know much about the topic he/she should have the fingers smacked. As this may depend very much of the current path. And also indeed current density, and type of body tissue. But the more energy absorbed by any tissue the more damage.
     
  6. tindel

    Active Member

    Sep 16, 2012
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    It's simple ohms law:

    voltage = current * resistance

    So if voltage / resistance is greater than 100mA then it can kill you.

    Depending on the source of information, I've see the current required to kill to be as low as 10mA! And the resistance of the human body to be as low as 2k hand to foot. This would make 20V lethal. That's kind of low, but if you just got out of the shower, and you were soaking wet then 20V might kill you.

    I really start being careful at around 30V.

    If you take this knowledge (current = voltage/resistance), assuming that your body resistance remains constant, then as voltage increases so does current and you can die quickly even with low current, high voltage sources.

    Current might be what actually kills you, but the voltage provides the potential (pun intended) to do the job!
     
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  7. MrChips

    Moderator

    Oct 2, 2009
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    The thing for the OP to put at the back of his/her mind is that it is the current level that is lethal.

    12mA can cause death.
     
  8. nsaspook

    AAC Fanatic!

    Aug 27, 2009
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    +1

    12mA seems like a very small current to cause damage but when you look at the conduction method and paths in a body it starts to make sense. At low currents the charge carriers in a body are not electrons like in a wire. Regions of high ionic concentrations like nerves and blood 'heart/brain' are the best paths for electrical current so these tissues are 'targeted' and are some of the most sensitive to electrical disturbance.
     
  9. t06afre

    AAC Fanatic!

    May 11, 2009
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    By the way I was not referring to you then I said the question was kind not so good. It was the source of the question I meant
     
  10. tahir51214

    Thread Starter New Member

    Nov 11, 2011
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    I don't care such things. I know just one thing, tell others what you know well and ask from others what you don't know. In this forum I never felt such feelings that any person ever had laughed at my question. Many senior members replied my awkward looking questions in so explaining style that I couldn't stop asking. I'm thankful to you and all other members specially Sir Chips for such good replies. My concepts are becoming stronger.
     
  11. tahir51214

    Thread Starter New Member

    Nov 11, 2011
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    So average body resistance for a normal dry person is round 2 kilo ohms.
     
  12. t06afre

    AAC Fanatic!

    May 11, 2009
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    First it is more the current densety that kill you. And the 12mA has to go directly trough the heart. It is many myths around this topic. And as for now I feel this is also highly influencing the answers given by the forum. One example is diathermy. That surgeon use cut tissue on daily basis. That is in basic a high frequency current.
    As I said before how leathel any electric shock may be depends As this may depend sevral conditions. The current path, the current density,and type of body tissue. Some body tissue like the heart, and nerves are more vunerable to electric shock. But other tissue may tolerate it quite well. I have seen sevral cervix(use google) being removed during surgery by using diathermy thecnique.
     
  13. #12

    Expert

    Nov 30, 2010
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    Take off any jewelry. A wedding ring keeps a moist spot under it. My first wife always believed I took my ring off to cheat on her, but that's because she was crazy. I took it off at work because I was working with everything from 5 volts to 30,000 volts and that stuff needs all the safety precautions you can!
     
  14. MrChips

    Moderator

    Oct 2, 2009
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    Good point. I don't wear any rings or jewelry for that reason.
     
  15. BillB3857

    Senior Member

    Feb 28, 2009
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    The only time I felt fearful of loss of my life was with 24VDC. Working in the equipment bay of an aircraft, I was laying full length on an aluminum try. Hot, humid weather resulted in my body being wet with sweat. My forearm happened to touch an uninsulated 24v buss bar and I could feel all the muscles on that side of my body tighten up. It took a firm concentration to move my arm away from the buss. I think I was lucky the current path did not go through my chest.
     
  16. electronewb

    Member

    Apr 24, 2012
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    Any difference on the type of current? AC and DC? I red that DC can cause more dammage than AC
     
  17. tahir51214

    Thread Starter New Member

    Nov 11, 2011
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    I think because of skin effect ac may not be that much dangerous. Also in ac circuits net impedance may be more than dc. Anyhow wait for seniors reply. They will guide you better.
     
  18. tindel

    Active Member

    Sep 16, 2012
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    BillB3857, No doubt in my mind that your story is true. Bus wires are also nothing to mess with - lots of power on those... Was it a regulated 24V bus?
     
  19. tindel

    Active Member

    Sep 16, 2012
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    I suspect the opposite is true - skin effect only comes in at high frequencies (above ~1MHz). I've yet to see a power system reach into this frequency range.

    House wiring is mostly safe because you do have low voltage parts of the sine wave where you can pull away and the frequency is slow, whereas if you are shocked by DC then you continue to be shocked and your muscles sieze/spasm and you have a hard time pulling away, as BillB3857 experienced.

    I could be wrong about all of this, but that's my intuition.
     
  20. t06afre

    AAC Fanatic!

    May 11, 2009
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