How a guitarist can be electrocuted through his guitar ? How to prevent it ?

Discussion in 'Luthier's Guitar & Bass Technical Discussion' started by bojocatkite, Sep 13, 2019.

  1. larry1096

    larry1096 Member

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    Think about it, though-if this were true, defibrillators couldn't work, since they're attached to the skin. If the skin were a better conductor than the interior of the body, the shock would simply run from one pad to another. And the shock doesn't have to be a large one-just enough to disrupt the rhythm generated by the sinus node, which is millivolts.

    Larry
     
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  2. Tone_Terrific

    Tone_Terrific Supporting Member

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    The current will seek multiple paths in accordance to Ohm's Law, more current over the lower resistance paths.
    The amount reaching the heart is unpredictable, but arm to arm is not a guaranteed death penalty (been there had that), and people have absorbed more than some of the figures that get touted about as being lethal. Those levels ARE lethal, applied to the heart, but do not reflect the reality of how people get shocks.
     
  3. offbeat

    offbeat Member

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    I used to think I was immune to stage shocks since I used EMG pickups with no ground wire. ...until I grabbed a metal mini-toggle switch while singing. The switch WAS grounded. Oops. My mustache was a little uneven the rest of the gig.
     
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  4. Killed_by_Death

    Killed_by_Death Member

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    I had this EXACT argument with an EMG endorser who swore by the ungrounded EMG pickups.
    I commented, "That's fine until you touch the controls!". I can't even remember his silly argument after that, he's not very technically inclined.
     
  5. gtrnstuff

    gtrnstuff Member

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    From Guitar Player Repair Guide 2nd edition, Safety Measures
    Paraphrasing Adrian Legg.
    Between the strings (bridge) and the string ground (sleeve of the output jack), insert a 220k ohm resistor parallel with a .001 cap minimum 500v.
    "Only lets about 40 volts through if a shock is headed your way."
    String ground functions normally (for shielding) but be aware touching controls or jack plate is not protected."

    I haven't tested this, but after a major shock that left my back and shoulder injured for almost a year, everybody be careful out there.
    Short story, at soundcheck, my guitar peg head touched the mic, both hands were on the strings. I couldn't move, couldn't walk.
    Stage tech saw it and knocked the mic away.
    Didn't lose consciousness, when the feeling came back I wished it hadn't (yet). Extremely painful.
    My little AC surge protector melted.
     
    Last edited: Sep 18, 2019
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  6. RicOkc

    RicOkc Member

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  7. Killed_by_Death

    Killed_by_Death Member

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    Tonight on Jeopardy! the clue had GFCI in there & none of the contestants could come up with "What is Ground Fault?!".
    That surprised me!
     
    Last edited: Sep 19, 2019
  8. gtrnstuff

    gtrnstuff Member

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    Like I was saying but much better with a picture. Thanks.
     
  9. GenoBluzGtr

    GenoBluzGtr Silver Supporting Member

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    https://en.wikipedia.org/wiki/Keith_Relf

    Keith Relf who played harmonica and sang lead vocals with Clapton, Beck and Page in the Yardbirds....

    Relevant sentence... "Relf died in the basement of his home in 1976 at age 33 from electrocution while playing an electric guitar."
     
  10. TrueFifth

    TrueFifth Member

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    Question regarding prevention:

    Can pedals between guitar and amp possibly prevent electrocution?


    Background:
    - I run multiple amp setups, sometimes with several vintage amps inline on several signal chains, comparable to Eric Johnson's setup with a lead path with a Marshall for crunch and another for lead, and a clean sound in stereo with 2 Fender amps, so sometimes up to 4 vintage amps inline.
    - Other times, I might 'just' use 3 fender amps, e.g. 2 champs beside a bigger Fender, like a W/D/W setup, which sounds like nirvana when used with e.g. 2 DMM's and a Lexicon LXP5.

    But I'm worried I'm playing with my destiny here, and will consult techs in the future, but it takes some time before I have gotten all my amps by for a checkup and fuse installs.

    I typically use Yamaha Magicstomps as splitters, so for example, 2 Magicstomps in series, that can give me 3 outputs to amps.

    Once I had a Magicstomp going bad because of a known failure in a resistor (I think it was), the solution is described online, where you clip it out of the circuit.

    What I do hope is, that the Magicstomp has so much sensitive components, that in case of a large current shock - that the Magicstomp will take the blast with a component failure, before it hits me - is that wrong thinking?
     
  11. Tone_Terrific

    Tone_Terrific Supporting Member

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    'Fraid so.
    In the unfortunate circumstance of a ground failure allowing voltage into the ground/shield the stomps would conduct it perfectly just as they connect to ground so well.
    See post #26 for the best suggestion to save your life.:D
     
  12. TrueFifth

    TrueFifth Member

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    OK, thanks, this makes me want to request - all guitarist should have a 'Safety Pedal' with a big red light bulb on it that can warn against faulty ground and have fuses to prevent lethal voltages in case of shock!
     
  13. Tone_Terrific

    Tone_Terrific Supporting Member

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    The circumstances that would put lethal voltage on the ground of your amp are already protected against in any normal situation.
    Guitarists are not dropping dead.
    Protecting oneself from being grounded when contacting an external dangerous source (other equipment) however is not a bad idea.
    See #26.
     

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