Dave Platt wrote:
In article ,
Ken Scharf wrote:
snip
HV isn't the only thing that can get you. High current can give you
a nasty surprise. Like the guy replacing some batteries on a golf cart.
He was using a ratchet wrench to tighten the battery clamps and he
ended on the most positive battery terminal. The handle of the wrench
hit the chassis of the golf cart putting it between 36 volts and ground
of some VERY HEAVY DUTY batteries. Ever see a Sears ratchet wrench
glow WHITE HOT? (and melt?)


Haven't seen that myself, but I've heard of people who have had
screwdrivers, etc. literally vaporized under such circumstances.

My brother came home from a business trip once with a scar on his wrist
5/8 inches wide and all the way around -- the truck was having
electrical problems & he shorted his metal watch band through the 12V
battery (there was a wrench involved in there somehow, of course).

I felt for him, but I was very glad that _he_ was the one to learn this
first hand, rather than me...

--
-------------------------------------------
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

On Thu, 14 Jul 2005 11:32:47 -0700, Tim Wescott wrote:
Dave Platt wrote:
In article ,
Ken Scharf wrote:
snip
HV isn't the only thing that can get you. High current can give you
a nasty surprise. Like the guy replacing some batteries on a golf cart.
He was using a ratchet wrench to tighten the battery clamps and he
ended on the most positive battery terminal. The handle of the wrench
hit the chassis of the golf cart putting it between 36 volts and ground
of some VERY HEAVY DUTY batteries. Ever see a Sears ratchet wrench
glow WHITE HOT? (and melt?)


Haven't seen that myself, but I've heard of people who have had
screwdrivers, etc. literally vaporized under such circumstances.

My brother came home from a business trip once with a scar on his wrist
5/8 inches wide and all the way around -- the truck was having
electrical problems & he shorted his metal watch band through the 12V
battery (there was a wrench involved in there somehow, of course).

I felt for him, but I was very glad that _he_ was the one to learn this
first hand, rather than me...

My dad (the first W3DHJ) told me a similar story.

It was in the late 20's. He was working on _his_ dad's Ford utility
truck. (Grandpa owned a dairy in Big Bear, Calif.) Six volts here.
The truck was parked in the driveway -- just outside the garage.
When my dad caught his ring between the positive terminal and the truck
frame, my Grandpa picked him up bodily -- ran him over to the rain barrel
at the corner of the garage -- and stuffed my dad's entire left arm (and
much of his upper torso) into the barrel.

( *The worst* thing you could do in a situation like that is try to _pull_
the ring off.)

My dad was a 90-day wonder in WW II. He then spent 25+ years in the
U.S. Army Corps of Engineers (we traveled the planet....) Most of his
duty assignments were as Post Engineer -- with the added responsibity
as Post Safety Officer. I always knew him to be evangelically anal
about safety. I'm sure that incident with the old Ford truck had a
wee bit to do with it.

Jonesy
--
Marvin L Jones | jonz | W3DHJ | linux
Pueblo, Colorado | @ | Jonesy | OS/2 __
38.24N 104.55W | config.com | DM78rf | SK

On Thu, 14 Jul 2005, Tim Wescott wrote:

Date: Thu, 14 Jul 2005 11:32:47 -0700
From: Tim Wescott
Newsgroups: rec.radio.amateur.homebrew
Subject: QUESTION: Fun with Svetlanas or Staying alive with kV power
supplies

Dave Platt wrote:
In article ,
Ken Scharf wrote:
snip
HV isn't the only thing that can get you. High current can give you
a nasty surprise. Like the guy replacing some batteries on a golf cart.
He was using a ratchet wrench to tighten the battery clamps and he
ended on the most positive battery terminal. The handle of the wrench hit
the chassis of the golf cart putting it between 36 volts and ground
of some VERY HEAVY DUTY batteries. Ever see a Sears ratchet wrench
glow WHITE HOT? (and melt?)


Haven't seen that myself, but I've heard of people who have had
screwdrivers, etc. literally vaporized under such circumstances.

My brother came home from a business trip once with a scar on his wrist 5/8
inches wide and all the way around -- the truck was having electrical
problems & he shorted his metal watch band through the 12V battery (there was
a wrench involved in there somehow, of course).

I felt for him, but I was very glad that _he_ was the one to learn this first
hand, rather than me...

I've got a related story to tell: I saw many years ago two guys try to
jump start another guy in the winter time. I only saw a few seconds and
surmised the following. These guys must have used the jumper cables to
connect the two twelve volt batteries in series, not parallel. Why? The
jumper cables were, themselves, literally smoking and not just a little
bit. Figure 24 volt power at, what, something like 500 amps(?) split
between heating up the interior of the two batteries and those jumper
cables (that are usually like #4 or #6 gauge?). How many seconds would it
take for on the order of 5000 watts to cause jumper cables to get up to
200-300+ degrees Farenheit? Those guys scrambled to tear those cables off
the batteries and I could tell by how they were handling the cable that it
had to be hot. They could have warped the lead plates.


--
-------------------------------------------
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com