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Got electrical shock today

  1. Feb 20, 2016 #1
    Today I was over at my wife's parent's house. My wife and her mom were doing a puzzle on a work bench. My wife told me she heard a buzzing under the work bench. Her mom has hearing problems and couldn't hear it but I certainly could, it was quite loud. I looked and it was coming from a lamp type wire in a box (guess it was plugged into a powerstrip somewhere). Looked like a wire was split wide open and it was nearly sparking. Long story short her mom didn't know it was live and proceeded to flail it around. It hit my thigh and gave me a shock. I was wearing jeans and thick soled hiking shoes standing on concrete floor. I was crouching and don't think I was holding anything, maybe a wood table leg. The shock wasn't too much, just gave me a scare. Just curious what the factors in this shock and just how much danger was I in?
     
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  3. Feb 20, 2016 #2

    fresh_42

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    We have here (Europe) the doubled value of voltage (220V) and unless you're suffering from severe heart problems or are another way of a weak constitution nothing will happen. Ok, you shouldn't do it taking a bath. I got my first shock as a kid when I tried to crack an old gaming machine my father got from somewhere to get the coins back. (There is also a famous song here which I call the electrician hymn: "Touched a 1000 times, a 1000 times has nothing happened, and then it has made boom!)
     
  4. Feb 20, 2016 #3

    CWatters

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    If enough current flows through your body it will kill you. I think anything over about 30mA has the potential to be fatal. The voltage needed to produce that current depends on the resistance of your body and the resistance between your skin and the source. So if you are well hydrated and sweaty then the voltage required will be lower. The path through you body also makes a difference. Thigh down leg to ground is going to be less dangerous than from one hand to the other via your heart. As I recall it's generally accepted that anything over about 42V has the potential to be fatal but it's unlikely at such a low voltage.

    What country are you in? I'm in the UK where the mains is 230V AC. That's more dangerous than the 110V used in the USA but I've survived at least three mains shocks - perhaps because I follow the rule.... If you really must work on live equipment best wear rubber soled shoes and keep one hand in your pocket. It doesn't guarantee you will survive a shock ut every little helps.
     
  5. Feb 20, 2016 #4

    russ_watters

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    Um hmmm...or maybe she has skills you weren't aware of and used them successfully and with plausible deniability? Clever, that one.
    Probably not much. Generally, power cord shocks involve touching both leads, which makes the electricity flow only a short distance, but even if you only touched one, the current would have a long way to go and through most of the mass of your body to get to your heart. It isn't a likely scenario for an electrocution.
     
  6. Feb 20, 2016 #5
    I knew a technician who used to check 220V appliances with his fingers. (I think he was crazy; don't do this.)

    The big problems are compromised skin resistance (wet, stuck with a needle, etc.) and current across the heart. You had neither and were safe-ish. However that was just lucky. Had you just spilled a drink or such it could have killed you. Rule of thumb: Don't mess with live wires.

    Not of concern here: Really high currents (think lightning) can also cause internal burns which often can't be felt. These can cause necrosis or organ damage killing days after the accident.
     
  7. Feb 20, 2016 #6
    Let me add a treatment suggestion: CPR. Hearts stopped by electric shocks can often be restarted by CPR. CPR doesn't usually help heart attacks (because it doesn't fix whatever was wrong in the first place), but works much better when the heart is otherwise healthy like after an electric shock.
     
  8. Feb 21, 2016 #7
    I'd say from my own experience that mains ac shocks are mostly dangerous if they happen to either stop the heart or cause ventricular fibrillation.
    Here in Europe we do have 230v and even this level of AC voltage doesn't hurt the body much if only for the heart , the heart surely is the weakest link when it comes to electricity.
    when I was a kid i touched a live 230v phase wire and the electricity ran through my arm down my body through my legs into the concrete pavement , since it passed the heart around the only thing that happened was that I couldn't feel my legs for some 2 minutes so I had to pull myself along using my arms.
    Also from other shocks I have mostly just felt very fast and a bit irregular heartbeat, apart from that I doubt that short term exposure to ac mains can cause any other major health problems except for the dangers of messing up the heart which is why I think it's still dangerous because sometimes for example when you get fibrillation even doctors can't stop it and if they can't do that in quite a short amount of time , well you basically die.
    So as the old safety books say , one should avoid the ac to pass from one arm to the other because that almoust definitely will go through the heart and as I said going through the heart is the concern. also one should avoid a diagonal current flow from left arm to right leg and right arm to left leg because that path also has a high chance of taking the heart in it's way.
    when i touched the live phase and neutral with my two fingers the current was almoust entirely going just throgh my fingers and not much into the body since i was standing on a isolated floor and so there wasn't much danger in that except for some tickling after effects felt into the fingers.
    not that i'm saying one should do that.

    I think DC has a higher potential to cause other than heart problems , like burning skin or internal organs due to the nature of DC current.
     
  9. Feb 21, 2016 #8

    jim hardy

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    I'm surprised the wire wasn't smoking and spitting sparks.

    Your shoes insulated you from the concrete floor , and the concrete is only a mediocre conductor.

    One can feel a current of 0.0001 amp and 0.001 will be sensed as a substantial shock.
    and around 0.01 amp it grabs your muscles hard enough you can't let go
    http://ecmweb.com/content/basics-electric-shock

    Jeff's technician friend presumably used the "Old Electrician's Digital VoltMeter" technique -
    OEDVM: Touch it with the BACK of your fingers so when your muscles contract from the shock it pulls your finger AWAY from the wire instead of grabbing it harder.
    That's how they live to be old electricians....

    I once quite accidentally got across an outboard motor spark plug - went in my left hand and out my right. I counted seven zaps as the engine rolled to a stop.
    Didn't bother my brand new Guidant pacemaker at all - more robust than they'd have you think .
     
  10. Feb 21, 2016 #9

    sophiecentaur

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    It always amazes me that people don't seem to know about this dodge. It can save a lot of discomfort and won't leave you quivering like an idiot.
     
  11. Feb 21, 2016 #10
    Caution required: You should not be out with your wife and especially not at her parents house. You may have actually been assaulted by her mom; I am familiar with such. What were you thinking? When I venture out with my wife, I insist she count it as a 'date'...so I get some credit!

    Some descriptions of what can go wrong here: https://en.wikipedia.org/wiki/Electric_shock

    "A sustained electric shock from AC at 120 V, 60 Hz is an especially dangerous source of ventricular fibrillation because it usually exceeds the let-go threshold, while not delivering enough initial energy to propel the person away from the source.

    That's roughly 20,000 volts or so on older breaker point type ignition systems. Automobiles, lawnmowers, snowblowers, all similar. If solid state ignition,common on all those nowadays, on the order of almost double the voltage. Stick with diesel engines if you are prone to grabbing uninsulated wires.

    USA ground fault circuit interrupters [GFCI] trip at about 5 ma, European about 30 ma. They protect but do not guarantee safety in all circumstances. Deaths in salt or fresh water around boats in marinas have caused a lot of investigations. Turns out smaller than expected leakage currents can be fatal to swimmers.

    This I did not know: [USA] UL has issued major revisions to UL 943, the standard for safety for GFCI that take effect on June 29, 2015.
    https://www.legrand.us/passandseymo...t-gfci/ul-943-gfci-standard.aspx#.Vsm4XX1OmXY

    Enough to avoid such situations when possible. I wonder how many people are electrocuted or seriously injured annually from, say 120 volts in dry household conditions.

    http://www.esfi.org/resource/holiday-data-and-statistics-359
    • Each year, there is an estimated average of 60 electrocutions associated with consumer products. The three most common product categories associated with electrocutions are small appliance, power tool, and lighting equipment.
    • Every year in the U.S., more than 2,600 people are killed in home fires.

    http://www.ecmag.com/section/safety/alarming-statistics [Likely construction, high voltage]

    “To the best of my knowledge, there are more than 30,000 nonfatal electrical shock accidents that occur each year, with a lot of incidents going unreported,” .... It is believed that for every 300,000 at-risk behaviors, there are about 300 recordable injuries, 30 lost-time injuries and one fatality.
     
  12. Feb 21, 2016 #11

    mfb

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    Better stick with no engines at all in that case.
    Why would you get close to a power cord that makes some noise?

    If the heart could be part of the current flow, it is a medical emergency for a day - even if there are no notable effects immediately, the heart can get problems later. The other parts should be fine if the shock was from 110 V, short in time and without notable effects.
    Sounds quite analog to me ;).
     
  13. Feb 21, 2016 #12
    It was under the bench and I didn't know what it was. I wasn't that close, just peeking under the bench. My mother in law then whipped the cord out. :rolleyes::mad:
     
  14. Feb 21, 2016 #13
    A dry concrete floor can have more than enough conductivity if you are bare foot, or even if your shoes are wet or moist.
    I was standing bare foot on a dry concrete floor when I reached to pulled the metal chain switch on a desk lamp. Due to a defect in the lamp the chain was shorted to the 120v hot wire. I remember seeing my hand contacting the chain, but I could not move away from it. My muscles were frozen. The next thing I remember I was laying on the floor very disoriented. The current felt like a vibration of millions of little needles puncturing my body (from the inside) from my right arm down to the concrete floor. Also, although I don't remember it, I must have yelled out or made some kind of noise because my mother came to the door and asked if I was ok. It was the worst electric shock I've ever received.
     
  15. Feb 21, 2016 #14
    There you go!
    Proof that mothers and mothers in law are quite different!
     
  16. Feb 21, 2016 #15

    jim hardy

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    Now there's first hand experience. Your fingers locked onto that chain by the shock?

    Thanks !


    That outboard was capacitive discharge electronic ignition. The spark is noticeably more intense than a lawnmower or 1950's outboard magneto.

    Oh my, the price will double again.
    I like the reversed wiring feature but not the automatic self test. I'm part Luddite.
     
  17. Feb 21, 2016 #16
    apart from the jokes about mother's in law which are funny as always MFB is actually very correct the thing most people don't know or don't remember that for some people problems with the heart after an shock can start showing themselves after some hours.
     
  18. Feb 21, 2016 #17

    dlgoff

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    Let this be a lesson; 115 vac is too often taken for granted as not dangerous.
    The "old timers" realized this possible problem. :approve:
    chain.jpg
     
  19. Feb 21, 2016 #18
    How are tazers considered safe? The videos look nasty where people get tazed. My shock was nothing like that.
     
  20. Feb 21, 2016 #19

    fresh_42

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  21. Feb 21, 2016 #20
    My fingers, and my whole body, were just frozen in place. I was saved by gravity.
    Very nice solution. I've never seen that before.
     
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