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I connected a PVC insulated alligator clip test lead to a 12V (give 20V) DC power supply positive terminal and a multimeter. After that I connected an other one to the multimeter ground, and a third one to the power supply negative terminal. I turned the multimeter to DC V measure mode. When I keep the two free alligator clips in my left and right hand, the multimeter show voltage. At the not insulated part of the clips I can see approx. 18.5-.8V but I understand this because electrons can go through my body. But if I keep the insulated part of those clips, I also can see voltage which depend on how strong I press the clips. It can go to 3-4V which is significant leakage. But if I keep and press the wires right below the clips, no leakage. Wires also PVC insulated and my multimeter can measure 100uV precision. I cannot keep strong enough to see any extra voltage. (On high precision mode multimeter always show 1-2mV.)

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  • $\begingroup$ When did you last clean the insulation on the clips? My guess is they are covered in a thin layer of conducting gunk - i.e. whatever has come off your fingers while using the probes over a period of time. $\endgroup$ – alephzero Apr 14 at 15:00
  • $\begingroup$ Note that alephzero's gunk will have salt in it from your perspiration, and if you are in a humid area, then leakage will be significant. $\endgroup$ – niels nielsen Apr 14 at 17:51

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