High Current Horror Stories
 

Hi all,

Anyone got any high-current/low-voltage horror stories they'd care to
share? You know; where your messin' about with a car battery or
something like that and forget to take your watch off or whatever.

p.
--

"What is now proved was once only imagin'd." - William Blake, 1793.

Hmmmmmmmmm......there was this time a few decades back a solder blob
caused a B-C short in the linear for my CB - Man, do the ceramic caps sure
fly off those MRF454's :-o

--
Gregg t3h g33k
"Ratings are for transistors....tubes have guidelines"
http://geek.scorpiorising.ca

My brother, circa 1965, was working on a six volt Chevrolet.

His ring got between the battery terminal and ground. (Don't ask me
how.)

He ended up with a destroyed ring and a finger with a very painful burn
around it.

No permanent damage but come to think about it he's a little weird even
today. Hmmm.... but isn't everybody weird but you and me and I sometimes
wonder about...

================

This is really not low voltage high current but an event that sticks in
my mind as potentially fatal.

I had a female student in one of my community college electronics class.
The electronic bench where she was working had a 8 foot strip of outlets
on one of the typical 1970s surface mount plug strips. She had plugged
in some instrument but in retrospect she hadn't pushed the plug in
completely, leaving a small amount of the metal of the plug exposed.

Around her waist she had a silver colored metal belt with a hanging end
with a washer shaped end on it. It looked to me like a dog collar.

She bent over the bench to adjust something and the metal end of her belt
went across the metal prongs of the plug.

RESULT = lots of sparks, a loud scream, a partially melted end to the
belt and a much wiser and more careful student. (And a very relieved
instructor, thankful that it hit BOTH prongs and not just one while she
was holding touching a grounded instrument case.

Yes, we then moved all the plug strips on the benches where they were
mounted to the bottom edge of the bench and removed them from other
benches where there were adequate outlets on the plug strip on the front
of the shelf along the back of the bench.

Paul Burridge wrote:

Hi all,

Anyone got any high-current/low-voltage horror stories they'd care to
share? You know; where your messin' about with a car battery or
something like that and forget to take your watch off or whatever.

p.
--

"What is now proved was once only imagin'd." - William Blake, 1793.

--
Address is NOT monitored due to SPAM volume from newsgroups. DO NOT
REPLY to post directly.

The place was Hong Kong.

It was around Xmas, 1945.

I was alone in the lab.

Working on a set of airborne radar equipment strewn around the workbench.

The scanner was not rotating, just pointing out of the open window, past a
Royal Navy cruiser moored in the harbour about a mile away and onwards to
Victoria City with the island's mountainous peaks in the background. All
displayed strong echos on the PPI on its 10-mile range.

As indicated on the PPI there was something intermittent.

I suspected a poor coaxial cable connection.

Familiarity breeds contempt.

Forgetting the equipment was still switched on I unscrewed one of the many
coaxial connectors and Pye plugs.

To clear out any foreign bodies I inserted the tip of by my right forefinger
into the vacant socket.

Now that particular socket was power output from the modulator unit on its
way to the transmitter unit. The transmitter was a 50 Kilowatt magnetron
which required unpteen thousand volts, pulsed at several hundred times
persecond with a one microsecond pulse width.

How long I lay on the floor I do not know. Probably only a few seconds.

I trembled all over which passed off after a few minutes. Apart from a white
burn on the afore-mentioned fingertip the after-effects were
sychological - it took several days to pluck up courage just to re-enter
the lab when I had difficulty looking in the direction of the offending plug
and socket.
---
Reg, G4FGQ

Paul Burridge wrote:
Hi all,

Anyone got any high-current/low-voltage horror stories they'd care to
share? You know; where your messin' about with a car battery or
something like that and forget to take your watch off or whatever.

p.
Well there was this guy changing batteries on a golf cart.
Had 6 very large 6 volt storage batteries wired in series.
He was using a ratchet wrench to remove the battery contact
clamps and while detaching the most postive end first (!)
the ratchet handle touched the frame of the golf cart.

Ever see a Sears ratchet glowing WHITE HOT?

Paul Burridge wrote:

Hi all,

Anyone got any high-current/low-voltage horror stories they'd care to
share? You know; where your messin' about with a car battery or
something like that and forget to take your watch off or whatever.

Though there is considerable voltage involved in the production of the
currents involved, it is the (forces of the magnetic field of the)
current that crushes the coins.
http://webpages.charter.net/tesla/crushed_coin.htm
--
John Popelish

On Sun, 15 Aug 2004 12:50:28 -0400, Ken Scharf hath writ:

Well there was this guy changing batteries on a golf cart.
Had 6 very large 6 volt storage batteries wired in series.
He was using a ratchet wrench to remove the battery contact
clamps and while detaching the most postive end first (!)
the ratchet handle touched the frame of the golf cart.

Ever see a Sears ratchet glowing WHITE HOT?

Ya, but... You can take it back and they'll replace it. HI!HI!

Jonesy
--
| Marvin L Jones | jonz | W3DHJ | linux
| Gunnison, Colorado | @ | Jonesy | OS/2 __
| 7,703' -- 2,345m | config.com | DM68mn SK

On 15 Aug 2004 18:17:32 GMT, Allodoxaphobia
wrote:

On Sun, 15 Aug 2004 12:50:28 -0400, Ken Scharf hath writ:

Well there was this guy changing batteries on a golf cart.
Had 6 very large 6 volt storage batteries wired in series.
He was using a ratchet wrench to remove the battery contact
clamps and while detaching the most postive end first (!)
the ratchet handle touched the frame of the golf cart.

Ever see a Sears ratchet glowing WHITE HOT?

Ya, but... You can take it back and they'll replace it. HI!HI!

Only if you don't melt the part that says "Craftsman".

Happy trails,
Gary (net.yogi.bear)
------------------------------------------------
at the 51st percentile of ursine intelligence

Gary D. Schwartz, Needham, MA, USA
Please reply to: garyDOTschwartzATpoboxDOTcom

On Sun, 15 Aug 2004 15:12:54 GMT, DO NOT REPLY to this ADDRESS hath writ:
My brother, circa 1965, was working on a six volt Chevrolet.

His ring got between the battery terminal and ground. (Don't ask me
how.)

He ended up with a destroyed ring and a finger with a very painful burn
around it.

No permanent damage but come to think about it he's a little weird even
today. Hmmm.... but isn't everybody weird but you and me and I sometimes
wonder about...

My dad (the first W3DHJ) told me an almost identical 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, too.
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 (Deputy) 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.

73
Jonesy
--
| Marvin L Jones | jonz | W3DHJ | linux
| Gunnison, Colorado | @ | Jonesy | OS/2 __
| 7,703' -- 2,345m | config.com | DM68mn SK

On Sun, 15 Aug 2004 12:01:14 +0100, Paul Burridge
wrote:

Anyone got any high-current/low-voltage horror stories they'd care to
share? You know; where your messin' about with a car battery or
something like that and forget to take your watch off or whatever.

I did once work with this sort of power, at a company which was making
superconductors. We had to test various samples at high current/low
voltage to determine some of the properties, while they were submerged
in various liquified gases.

One project involved setting up a two-module 1000 watt DC power
supply. I "wired" them together using copper bar stock 1" by 1/4",
bent to fit the terminals, and plated with silver for lower contact
resistance. The connection to the samples was with 2 ought welding
cable, which was about 1-1/8" in diameter with insulation.

I have also worked with high voltage RF up to 20 kV, but that is
another story.

The general rule is when you are working with KIL-o-amps, KIL-o-volts,
or KIL-o-watts, is to make sure you don't get KILL-ed.

Happy trails,
Gary (net.yogi.bear)
------------------------------------------------
at the 51st percentile of ursine intelligence

Gary D. Schwartz, Needham, MA, USA
Please reply to: garyDOTschwartzATpoboxDOTcom