My comment is 22 nF is an awful lot of stray capacitance. If I were in my screen room and wearing thin soled shoes standing on grounded metal sheet I could see it, but not in a home environment where there is a large separation between every part of my body and ground.
> From: Ron Pickard <[email protected]> > Date: Thu, 2 Dec 2004 17:12:23 -0700 > To: [email protected] > Cc: [email protected] > Subject: Re: Is one-handed electrical shock possible? > > > > > > Hi Ken, > > As with you and Gary and I'm fairly sure with just about everyone else on this > list, I've had some > experiences, too. However, I won't share any of them, but suffice it to say as > Gary so eloquently > relayed it "Stupid is as stupid does". You can draw your own pictures. > > IMHO, the main resistive element is not restricted to only resistance. Think > of it more as > impedance, with capacitive reactance coming into play. Actually, if you think > about it, a capacitor > is a fairly good insulator with DC voltage applied. But, if the impedance is > strictly capacitive > (ignoring resistance) and doing a quick calculation with 120Vac 60Hz voltage > being present and > producing a current of 1mA, this yields a capacitance of about 0.022uF (or > 22nF) with a reactance of > about 115Kohms, which falls in line with your 120Kohm resistance estimate. > > Comments? > > Best regards, > > Ron Pickard > [email protected] > > > > ken.javor@emccomplian > ce.com To: [email protected] > Sent by: cc: > owner-emc-pstc@listse Subject: Re: Is one-handed electrical shock > possible? > rv.ieee.org > > > 12/02/2004 04:24 PM > > > > > There have been a great many anecdotal tales submitted, and I could add my > own hair-raising adventures. I suspect just about anyone living in the > civilized world in the latter half of the 20th or beginning of the 21st > century has at one time or other experienced a one-handed shock. > > So the possibility exists, it is undeniable. What is less clear to me, and > what I believe was the point of the original post, and which has not been > answered at least to my understanding, is how does it happen? > > To my way of looking at it, the resistance/capacitance of the human body is > not an issue; if you place mains potential across the body, current will > flow and damage will ensue. What is interesting is that the one-handed > shock can occur when the body is (again, to my understanding) ungrounded and > potentially speaking, floating. The last time I got shocked I was doing > something very similar to Mr. McInturff. Having for the third time bought a > new (for me) home in Alabama, I was going through the ritual of rotating the > electrical outlets. For some reason older homes in Alabama have the outlets > installed with the safety ground jack up instead of down. Sometimes that is > inconvenient, so I rotate them. Like Mr. McInturff, I didn't want to throw > the breaker and was trying to be careful. > > I was sitting on the floor. The floor is covered with wall-to-wall carpet, > which is likely man-made, say nylon or rayon, a pretty good insulator. > Underneath the carpet is the pad, again insulator. Underneath the pad is > the concrete slab. Probably a conductor at a high enough potential, but I > would expect a pretty good insulator at 120 Vac. > > Well, I pulled a McInturff and got a good buzz. I don't know if it was > surprise or muscular contraction, but my leg shot out and I almost broke > something. > > I think 1 mA is supposed to elicit a "surprise" reaction. Someone on the > list please correct me if I'm wrong. If 1 mA was coursing though my body, > that means that the line-to-ground resistance total was only 120 kOhms. I > can't account for that. > > Comments? > > Ken Javor > > ---------------------------------------------------------------- > This message is from the IEEE Product Safety Engineering Society > emc-pstc discussion list. Website: http://www.ieee-pses.org/ > > To post a message to the list, send your e-mail to [email protected] > > Instructions: http://listserv.ieee.org/listserv/request/user-guide.html > > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > > Ron Pickard: [email protected] > Scott Douglas [email protected] > > For policy questions, send mail to: > > Richard Nute: [email protected] > Jim Bacher: [email protected] > > All emc-pstc postings are archived and searchable on the web at: > > http://www.ieeecommunities.org/emc-pstc > > > This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Ron Pickard: [email protected] Scott Douglas [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
