28

It is said that if someone accidentally touches a powerful electric source, they get stuck to it and often die due to the same effect. Is it true, or it is just a perception of the affected person?

Kit Sunde
  • 18,636
  • 12
  • 93
  • 127
smUsamaShah
  • 2,343
  • 4
  • 24
  • 32

1 Answers1

46

What happens is not due to some stickiness inherent to electricity, but rather, the electric shock causes your muscles to involuntarily contract. If you're unlucky, such a contraction could effect a firm grip around the electric source, which would render you unable to let go of it.

All about circuits elaborates:

The forearm muscles responsible for bending fingers tend to be better developed than those muscles responsible for extending fingers, and so if both sets of muscles try to contract because of an electric current conducted through the person's arm, the "bending" muscles will win, clenching the fingers into a fist. If the conductor delivering current to the victim faces the palm of his or her hand, this clenching action will force the hand to grasp the wire firmly, thus worsening the situation by securing excellent contact with the wire. The victim will be completely unable to let go of the wire.

David Hedlund
  • 7,766
  • 1
  • 43
  • 37
  • 16
    that is why i was always taught, if you try a fence to see if its electrical, touch it with the back of your hand. – Andy May 11 '11 at 15:18
  • I touched an electric fence once and I thought the guy behind me had just punched me in the back. – Nobody May 11 '11 at 15:57
  • I've heard there's a difference here between AC and DC power. AC power will cause your muscles to contract a bit but then the current will switch and you'll get pushed away by the electric force. No data to back this up though. I've heard that if Edison had his way, we'd all be using DC and there would be many more deaths from this DC death grip. – jcollum May 11 '11 at 17:04
  • 5
    @jcollum that isn't true. The AC current will cause periodic contractions (at a rate of 60HZ or w/e the local mains rate is), but reversing the current won't "reverse" the contraction direction. We picked AC over DC through a combination of propoganda/hysteria (over the ideas expressed in your comment) and the rational conclusion that AC is much more efficient (in terms of losses) over large distances, in addition to the fact that its easier to upconvert AC (from the generator to thousands of volts for transmission) than it is to convert DC voltages. – crasic May 11 '11 at 17:36
  • 4
    @crasic Tesla was the man. @jcollum On crasic's point...AC is a "buzz" DC hits like a sledgehammer. – Rusty May 11 '11 at 17:43
  • 4
    @Rusty At mains level voltages, both hit like a sledgehammer :D – crasic May 11 '11 at 17:46
  • @Rusty, +1 for correcting who tried to push DC. – Kevin Peno May 11 '11 at 18:49
  • 2
    "Direct current (DC) is more likely to cause muscle tetanus than alternating current (AC), making DC more likely to "freeze" a victim in a shock scenario" http://www.allaboutcircuits.com/vol_1/chpt_3/2.html – jcollum May 11 '11 at 20:16
  • 1
    @jcollum @crasic: I wrote a blog post about this :) Though, crasic already stated all the major points. See [here](http://www.blueraja.com/blog/176/why-do-we-use-alternating-current-ac-instead-of-direct-current-dc-in-power-lines). @Kevin: Actually, @crasic is correct: Tesla pushed AC, Edison pushed DC. In the end, Tesla won. – BlueRaja - Danny Pflughoeft May 11 '11 at 20:56
  • @jcollum, @Danny Pflughoeft 1. The propaganda/hysteria was directed towards AC, such as with Edison's electrocuting an elephant with AC. 2. I don't know if you can really say that Tesla won in the end, considering he died penniless and sick in a hotel room in New York that he had lived in for a decade. By the way, here's an interesting letter about Tesla to Herbert Hoover from Louis Adamic sent 3 days before Tesla died: http://www.lettersofnote.com/2010/01/ordinary-standards-do-not-apply-to.html – Phoenix May 11 '11 at 22:04
  • 13
    I worked on a film soundstage at one point and I noticed the lighting crew had several wooden baseball bats with their gear. They explained the bats were for breaking the arms of people who accidentally touched a high-voltage cable, had their muscles seize up, and couldn't let go. The victim would be unable to overpower the involuntary muscle contractions, but the force of the bat would be enough to knock loose even the strongest grip. Whenever a crew member was working on a high-voltage cable, a second man carrying one of the bats was always with him. – bta May 11 '11 at 22:37
  • @crasic: AC is not more efficient over long distances. There's a reason ABB and other companies successfully sell HVDC links for really long power lines. True about conversion though, which was probably the big selling point before we had high power electronics. – Macke May 12 '11 at 21:35