🚀 go-pugleaf

In article <1992Apr12.140143.420@cmkrnl.com> jeh@cmkrnl.com writes:
>
>I agree with Mike.  In fact I think you can get a deadly shock from such a
>transformer even if you are standing on the semi-mythical dry wood on glass
>insulators (do you know anyone who actually works that way?), and even if you
>touch the "hot" terminal with only one hand.  It's true that under these
>conditions the current has "no place to go", ie no ground path, but there will
>still be a very brief current flow as your body "charges up" to the potential
>of the hot terminal. 
>
>I have no idea if this amount of current, for this brief time, would be lethal
>or not, but I'm not gonna test it!  This isn't a test you get to go back and do
>over again! 
>
>Bear in mind that the shock itself doesn't have to kill you to be dangerous. 
>The shock may kill or maim by doing nothing more exotic than causing your 
>muscles to convulse, throwing you against the wall or onto the floor with 
>extreme violence.  (This is a particular hazard when working around TV sets
>without discharging the CRT 2nd anode.  The shock itself might not be lethal
>but it might cause you to swing your hand into the neck of the CRT, and if your 
>hand is holding a tool, there's a good chance of breaking it... and the 
>resulting implosion won't be pretty.)
>
>	--- Jamie Hanrahan, Kernel Mode Consulting, San Diego CA
>Internet:  jeh@cmkrnl.com, hanrahan@eisner.decus.org, or jeh@crash.cts.com
>Uucp:  ...{crash,eisner,uunet}!cmkrnl!jeh

Let's see - under the conditions of standing on a "perfect insulator," the
current limit would be determined by the capacitive reactance to ground
at 60 Hz, which should be quite high, since the capacitance will be on the
order of pf...

BTW - I found out about all of this the hard way.  I was in the eight or
ninth grade, and messing around with a sign transformer in the basement.
I had the sense to use automotive ignition wire on the secondary, and
had observed a fine corona when I brought one  wire near the insulation
of the other secondary lead.  So I had the not-so-bright idea of holding
a screwdriver in one hand, grasping the insulation of one lead, and
attempting to draw a fine corona from the other *terminal* off the 
screwdriver point.  The result was a fat yellow arc about an inch long.
My arm snapped back, and the screwdriver stuck in the wall behind me.
My arm and legs hurt for several days.  I learned to be a *lot* more
careful very quickly :-)  One of the worst shocks I ever received.

Amazing some of us ever reach legal maturity, isn't it?

--joe pollock   pollock@u.washington.edu