🚀 go-pugleaf

Shock, but true:

While I was working with industrial induction heating equipment, I experienced
the worst shock of my life.  We had a test setup for new inverters, and triple
'0' locomotive cables of 480V 3ph. hanging around.  Normally I was very careful
because not only was there a lot of juice (480V input, 750V DC bus, 1500V peaks
on the 3-10khz output), but they were water cooled and of course always leaked
onto the floor.  One day I turned on the wrong 500A breaker, walked behind a
big inverter cabinet, and promptly ran my head into a live locomotive cable
hanging from a 2x4 between boxes.  Ahhhhh!!  My head was a big balloon that was
being inflated much too far.  I was looking out through a green translucent
force field.  Sparks were flying.  Fortunately, when my head contacted the
cable it caused one of the other phases to short to a grounded cabinet and
trip the 500A breaker.  It was over in a moment and I was running.  A co-worker
said he heard the noise, saw a big flash, turned around and I was gone.
I know what Ted Bundy felt like.  I was wearing cowboy boots and standing on
the usual damp concrete floor.  It was only 277V to ground from a wye, of
course.  My boss came out and asked me if it was my "first big one".
We used to use a big tank of water with hanging aluminum plates for a test
load.  One fellow decided to pour more salt water in from a metal bucket
while the thing was running.  Ahhhh!  Worse than pissing on an electric fence!
A customer told me of getting his hand wrapped around the fat braid to one
of the DC input diodes.  277V and he couldn't let go.  So he brought his
other hand up to yank his arm away.  But it somehow grabbed the next diode
braid and the other phase!  Now he had 480 (more like 510V) across the
hands.  Luckily they were pressed together, so it probably didn't go through
his whole body.  He collapsed into the box, yanking his arms off the 3/4"
diode braids.  How he missed the 750V DC buss made of water cooled 1/2"
copper pipe, I don't know.  It was in the bottom of the box.
The RF units were the most dangerous.  10,000V at 5A made a big input xfrmr.
And with the Q of the giant tank circuit, lots of high voltage around.
I had heard horror stories of people just pointing at something from 6 inches
or more and getting fried to heaven.  On the site, customers would point
to something and I would yell "Don't do that!".
Other items too numerous to mention.  I did field service on induction
heaters for a couple of years and met lots of HV, explosions, sparks, etc.
Our biggest product was 1.2MW and I had to go the Niagara Falls to fix it.

Now its only 5V and not very scary.

WA7LDV


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