which path does electricity take when conducted thru bodily tissues

Discussion in 'General Electronics Chat' started by pager48, Mar 22, 2019.

  1. SamR

    Active Member

    Mar 19, 2019
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    The entire body is a weak saline solution saturated sponge. The only difference is the veins and arteries pump platelets and plasma. Platelets are the iron rich oxygen carriers and plasma is the same solution the body is saturated with. So veins and arteries are no more conductive than the surrounding tissue. From what the BME article said there is no more conductive part than any other except for current/cross sectional area. What I did find interesting was that hand to hand conduction across the heart/chest was 60% fatal compared to 20% for hand to opposite foot conduction. Go figure, I've seen countless warnings about hand to hand conduction and keeping one hand in your back pocket.. Rubber soled (or all rubber) shoes/boots may give some protection in a dry environment. I've sat through safety presentations dealing with downed power lines and one thing they tell you is keep your feet together to eliminate potential V difference between them (if you accidently are in a downed line situation that could not be avoided). Hop, not walk, to escape the area if you can't wait for the line to be deenergized (and if you fall over doing it you are dead). Guys that work with distribution lines wear long cuff rubber gauntlets under their leather ones. Before putting them on they pinch the cuff together and roll them up to insure they hold air like a balloon to check for any perforations of the rubber that could cause a high voltage current path.
     
    Last edited: Mar 23, 2019
  2. jpanhalt

    Expert

    Jan 18, 2008
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    1) Platelets are not oxygen carriers. They are important in clotting. Red blood cells (RBC) may be what you intended to say. By volume, platelets are a small proportion of blood. I didn't find quickly anything that said RBC conduct current better than plasma; although, I doubt it. A standard method for counting RBC's/hematocrit is by the increase in impedance as the plasma+RBC pass through a small orifice (https://acutecaretesting.org/en/articles/hematocrit--a-review-of-different-analytical-methods ).

    2) Here's what the article I posted said: "Leibovici et al. (1995) reported that current passing through the thorax is associated with 60% of electrocutions, whereas for current passing from leg to leg it is 20%." It's leg to leg, not hand to leg. There is some conflicting opinion on the most dangerous path as the reports are not corrected for prevalence (e.g., one might expect hand to hand more frequently than foot to foot). The article makes this caveat, "These numbers do not address the over-all (including not fatal) chances of exposure at each geometry nor do they distinguish across high/low voltage exposure levels." Anatomically, hand to hand does not go over the heart; whereas , left hand to right foot does.

    3) If you look up the history of the "one hand in your pocket" recommendation, that is based on decreasing the risk of getting shocked, not the lethality of such shock.

    4) The recommendation for hopping rather than walking comes up often. Some have even gone so far as to recommend hopping on one leg. I think that is a horrible recommendation. Shuffling is probably the far better way to get away. Most people are not very good at hopping, particularly on one leg. Given the typically adverse weather (e.g., wet grass, ice) and excitement that occurs with downed power lines, shuffling is far and away a more stable way to move. If you hop and fall, which is likely to happen, your hand and feet are pretty far apart and would increase the likelihood that the current would be hand to foot across the thorax.
     
  3. eetech00

    Senior Member

    Jun 8, 2013
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    The question is incomplete.

    eT
     
  4. SamR

    Active Member

    Mar 19, 2019
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    I stand corrected. I do remember the hand to opposite foot from somewhere... We were basically told not to move in a downed line event. That included not exiting a wrecked vehicle unless it was on fire. I have a 3 phase high voltage distribution line in front of my house (100' away). Several times I've be treated to a massive arc display as it became grounded to a tree limb. Awesome and frightening event. Brilliant arc flashes and quite loud "humming/buzzing" sound that is unforgettable. After about 3-5 short (a few seconds) arcs it trips a line breaker feeding it. Even in the house with the blinds drawn you hear and see it. One massive Jacob's ladder. I watch from the porch and stay away.
     
    Last edited: Mar 23, 2019
  5. SamR

    Active Member

    Mar 19, 2019
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    Also... From time to time there will be a huge explosion outside and the lights go off. Squirrels and 15KVA transformers don't go together very well. They electrocute themselves between the terminals on the transformer blowing the transformer's fuse which sounds like a stick of dynamite going off and there is not much if anything left of the squirrel to show for it.
     
  6. ian field

    AAC Fanatic!

    Oct 27, 2012
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    If you're lucky - once the current burns a hole in the skin, the wet stuff underneath is *MUCH* more conductive.
     
  7. nsaspook

    Expert

    Aug 27, 2009
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    My friend was Lucky that most of the electrical burn damage was on things that could be replaced from his legs (skin and vascular tissues.)
     
  8. ian field

    AAC Fanatic!

    Oct 27, 2012
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    I found out that arc burn ulcers take weeks to heal - I didn't feel anything at all (alerted by the smell of burning flesh) till I actually saw the injury.
     
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