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I have a small snow machine that I purchased. It comes in a wooden box with metal, I assume aluminum or maybe stainless steel, trim around it. It connects directly to a standard 110vac power. Obviously there is liquid involved as well.

The strangest thing is happening. I have one worker who, whenever he touches the metal trim, gets shocked. It is continuous and happens regardless of how many times he touches it, so it isn't static. Everyone else can touch it without getting shocked. But if he touches someone while they are touching it, they both get shocked. He has tried different clothing, shoes, etc to figure out why he is the only one, but no matter what, he is the only one who gets shocked.

It makes no difference if the machine is turned off or on.

Anyone have any ideas? It's got me stumped.

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    \$\begingroup\$ Does he "get shocked" or can he feel a very faint tingle like a very gentle vibration? I find I can sometimes detect low AC currents from equipment without a proper ground connection, some other people can't feel anything, but a multimeter shows 10s of microamps there. (In one case, it turned out to be capacitive coupling through a mains transformer) \$\endgroup\$
    – user16324
    Commented Oct 27, 2016 at 16:55
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    \$\begingroup\$ I don't have an answer, but you seriously need to test whether the metal trim is Earthed, and test what voltage to Earth you get from it with a voltmeter. For safety's sake. \$\endgroup\$
    – Ian Bland
    Commented Oct 27, 2016 at 16:57
  • \$\begingroup\$ Is he a really big dude hence has quite high capacitance to earth (compared to the other folk)? \$\endgroup\$
    – Andy aka
    Commented Oct 27, 2016 at 16:58
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    \$\begingroup\$ @IanBland : very good point with exposed metal, mains electricity and water. \$\endgroup\$
    – user16324
    Commented Oct 27, 2016 at 17:19
  • \$\begingroup\$ Brian Drummond. He yanks his hand away and says it hurts. \$\endgroup\$ Commented Oct 27, 2016 at 17:45

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The shoes and socks can be leather and with sweat and conduct many uA of current.

  • e.g. 230V/1M = 230 uA.
  • dry socks and synthetic soles can be >>50M or 230V/50M=<5uA
  • If the insulation leakage in the machine is rated to 0.5mA then it's impedance is 230V/0.5mA = 460 kOhm
  • so shoe interface impedance makes all the difference.

The machine has leakage current and 0.5mA (500 uA) can be felt but is generally considered safe and is the IEC/UL/CSA limit. It may be more and you ought to try measure it and fix it.

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  • \$\begingroup\$ I will try to measure it. \$\endgroup\$ Commented Oct 27, 2016 at 17:46

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