Big short circuit stories?
gorgon...@my-deja.com
LITTLE SPARKS WHEN YOU SCREW UP YOUR CAR STERO INSTALL- I MEAN BIG
HAIRY SPARKS AND JOLTS THAT SCARED THE CRAP OUT OF YOU!
STUFF LIKE:
POWER COMPANY 'FAULTS', MASSIVE BATTERY BANK SHORTS, 3RD RAIL
VIOLATIONS, POLE PIG FIRES, TOOLS ACROSS BUSBARS, TRANSMITTER
ARCING, TESLA PROJECTS GONE AWRY, MEGA-AMP MELTDOWNS,
PENNY-IN-THE-FUSEBOX ANTICS, MOTOR-GENERATOR MISHAPS, MISWIRED
MAINS, ELECTRIC MAYHEM, POWER LINES DOWN, BREAKERS THAT WON'T
TRIP, HIGH-VOLTAGE CRAZINESS, ETC.
LET'S HEAR SOME GOOD ONES AND THEN I'LL POST SOME TOO. WHO
HAS THE BEST TALES TO TELL? ANY YOU EX-MILITARY GUYS HAVE SOME
GOOD STUFF TO SHARE?
GORGONZOLA 57
OVER AND OUT.
Sent via Deja.com http://www.deja.com/
Before you buy.
CVI
the T over the Salt & Pepper Shaker bridge from Boston to Kendall Square in
Cambridge when I noticed that ALL the lights in Cambridge were slowly
dimming down to black and back up again to full bright! When I got back
to my dorm 15 minutes later they were still doing it and it probably took
another 1/2 hour to shut the power grid down. As time went on the cyclic
dimming got slower and slower as the faulty generator in Cambridge gradually
slowed down. The paper the next day said that the problem was caused by
come circuit breakers welding themself shut when the fault occured so that
the power company could not readily disconnect Cambridge from the rest of
the grit. MIT had its own power plant at the time and was able to
disconnect the school from the grid once their generator got up to speed and
restore normal power, but not before dozens of experiments that had been
running uninterupted for years were damaged.
Gerry
George P. Cotsonas
of mine told me a story of how some large light towers surrounding their
encampment went out in some heavy storm conditions. The power was shut
down, it was pitch black, and he was sent out in waist deep water to
investigate the supply cables.
Well, someone (though it was later well covered up, and the culprit
could not be identified) turned up the power while he was out there,
and, being well-immersed, he fried, almost to death. Curled my hair to
hear the story.
George the Greek
P.S.: liked the Cambridge brownout story in this thread.
gorgon...@my-deja.com wrote:
> IT WOULD BE NICE TO HEAR STORIES ABOUT BIG SHORT CIRCUITS. ... ANY
Not Me
>IT WOULD BE NICE TO HEAR STORIES ABOUT BIG SHORT CIRCUITS. NO, NOT
>LITTLE SPARKS WHEN YOU SCREW UP YOUR CAR STERO INSTALL- I MEAN BIG
>HAIRY SPARKS AND JOLTS THAT SCARED THE CRAP OUT OF YOU!
>
Managing to short out a backup power supply battery tray inside a
cabinet. 12 batteries, 72 volts, lots of amps - the backup was rated
for something like 8 hours. Most embarassing was explaining why we
needed to replace brand new batteries.
Second time was carefully disconnecting a 220 volt power cord from th
eback of a computer in order to shorten it. As I cut off the excess,
the shower of sparks and melting of the heavy duty cutters gave me a
hint that I had neglected to remove power from the cord. Oops!
Last one - watching an instrument tech at a chemical plant short out
and blow the breaker on a panel controlling one third of a major
process unit. Not too many sparks, but the alarms going off deafened
everyon. A mere 8 hours later the plant was back up.
Bill
several large (mini) computer systems.... A company I worked for decided to
open up the computer installation field to females. Well one of these
females was given the job of installing a new large computer system. There
was not a proper outlet for the computer in the computer room, so she
decided to change the plug on the computer to a plug that would work in one
of the existing outlets. (Rather than calling an electrician and having the
proper outlet installed as she should have done...) Anyway she miswired the
new plug and wired the ground wire to hot. She then plugged in the plug and
zapppppp! Smoke everywhere... Two other large computer systems had multiple
data lines with ground connecting to the new system. (Their grounds went to
ground.) All three large computer systems were fried beyond repair. I think
almost every circuit board in each computer had damage. I guess all those
chips did not like 120VAC too much.
Don Libby
>
> IT WOULD BE NICE TO HEAR STORIES ABOUT BIG SHORT CIRCUITS. NO, NOT
> LITTLE SPARKS WHEN YOU SCREW UP YOUR CAR STERO INSTALL- I MEAN BIG
> HAIRY SPARKS AND JOLTS THAT SCARED THE CRAP OUT OF YOU!
>
Inadequately grounded steel-framed building in a midwestern thunderstorm
-- six foot bolt of lightning arcing across the hallway from the left
side of the metal doorframe I'm standing in to the metal doorframe
across the hall. I love the smell of ozone in the morning.
-dl
--
*********************************************************
* Replace "never.spam" with "dlibby" to reply by e-mail *
*********************************************************
davefr
they have some of the best lightning storms around. Lightning is the
ultimate short circuit!
In article <906p6g$23$1...@nnrp1.deja.com>,
gorgon...@my-deja.com wrote:
> IT WOULD BE NICE TO HEAR STORIES ABOUT BIG SHORT CIRCUITS. NO, NOT
> LITTLE SPARKS WHEN YOU SCREW UP YOUR CAR STERO INSTALL- I MEAN BIG
> HAIRY SPARKS AND JOLTS THAT SCARED THE CRAP OUT OF YOU!
>
> STUFF LIKE:
>
> POWER COMPANY 'FAULTS', MASSIVE BATTERY BANK SHORTS, 3RD RAIL
> VIOLATIONS, POLE PIG FIRES, TOOLS ACROSS BUSBARS, TRANSMITTER
> ARCING, TESLA PROJECTS GONE AWRY, MEGA-AMP MELTDOWNS,
> PENNY-IN-THE-FUSEBOX ANTICS, MOTOR-GENERATOR MISHAPS, MISWIRED
> MAINS, ELECTRIC MAYHEM, POWER LINES DOWN, BREAKERS THAT WON'T
> TRIP, HIGH-VOLTAGE CRAZINESS, ETC.
>
> LET'S HEAR SOME GOOD ONES AND THEN I'LL POST SOME TOO. WHO
> HAS THE BEST TALES TO TELL? ANY YOU EX-MILITARY GUYS HAVE SOME
> GOOD STUFF TO SHARE?
>
> GORGONZOLA 57
Cm Heong
Heong
"George P. Cotsonas" wrote:
>
> Luckily I did not enjoy the pleasures of Vietnam, but a former colleague
> of mine told me a story of how some large light towers surrounding their
> encampment went out in some heavy storm conditions. The power was shut
> down, it was pitch black, and he was sent out in waist deep water to
> investigate the supply cables.
>
> Well, someone (though it was later well covered up, and the culprit
> could not be identified) turned up the power while he was out there,
> and, being well-immersed, he fried, almost to death. Curled my hair to
> hear the story.
>
> George the Greek
>
> P.S.: liked the Cambridge brownout story in this thread.
>
> gorgon...@my-deja.com wrote:
>
> > IT WOULD BE NICE TO HEAR STORIES ABOUT BIG SHORT CIRCUITS. ... ANY
Ben Franklin VI
manufacturing plant from downtown to the industrial park. A three phase, 240,
200A direct metered panel which was fed by the same bank of three, 500KVA
transformers.
My friend at the power company said -- when you are ready call and I will pull
the meter. I pulled it myself. Took out the panel.
Now why call bother Paul, I'll just put the meter back so no one can touch the
feeders.
The metal ring on the meter contacted the top lugs on the meter base.
Vaporized the ring and began an arc that continued until the transformer fuses
blew. Five megawatt furnace for about 10 seconds. I moved away fast and
instinct closed my eyes. Maybe half to one second near an electric fire ball
was to much.
Down town was powerless, I could not see, no electrical shock remembered --
burns, everywhere heat radiation could get to bare skin. I had one of my men
drop me at the hospital. I could see the shapes -- all in shades of dark red.
I told the nurse what I needed and laid down on the floor to pass out. She
said -- "We cannot admit you without your doctor being here". I got up and
went out the door toward Dr. Moore's office three blocks away. A crippled
fellow just getting into his car -- I said you must take me to Dr. Moore.
I laid on DR's. table -- Nurse Trudy looked in my eyes, turned white and
slumped. She thought my contacts were detached retinas. There were small
balls of copper on my eyelids and face. The wrists where you look for pulse
were fried as was the face and neck where the shirt was open. Doc used a roll
or two of gauze and I went back to work. No skin grafts. The chambray long
sleeved work shirt protected my arms and chest. The burns were heat and
radiation burns -- only on exposed, uncovered skin.
Paul said, Ben, you should have called! Next time I did.
Every man is a damn fool for at least five minutes every day. Wisdom consists
in not exceeding the limit. BENJAMIN FRANKLIN, Poor Richard's Almanack, 1755
THAT DAY in 1960 five minutes was to much!
Ben VI
>rom: gorgon...@my-deja.com
>Date: 11/30/00 5:51 PM
>
>IT WOULD BE NICE TO HEAR
None preaches better than the ant, and she says nothing. B. FRANKLIN, Poor
Richard's Almanack, 1736.
Quality is remembered long after price is forgotten. Ben VI
The bitterness of poor quality remains long
after the sweetness of low price fades.
John Wasser
In article <906p6g$23$1...@nnrp1.deja.com>, <gorgon...@my-deja.com>
wrote:
> IT WOULD BE NICE TO HEAR STORIES ABOUT BIG SHORT CIRCUITS.
Here's my favorite:
Date: Wed, 27 Sep 89 10:27 PDT
From: "Thomas L. Mc Mahon" <t...@riverside.scrc.symbolics.com>
Subject: Cuts and jumpers (on a different scale)
To: Hard...@riverside.scrc.symbolics.com
[Not quite the right mailing list but close. If you don't care about
megawatts, bus bars bigger than your wrist, things that cause ground
loops out to Hawaii, or big hairy construction projects hit D now.]
---
Several days ago a very large number of trucks and men from the Los
Angeles Department of Water and Power descended on my neighborhood.
They removed large sections of Pershing drive to a depth of 15 feet or
so over a stretch of about a city block. I assumed they had a problem
with a water main or something.
When they started building semi-permanent structures over the holes I
knew something really big was up. When the large trucks full of strange
power tools, mega-welding machines, breathing equipment, and racks of
test equipment came I started wondering. Driving by a couple nights ago
(11 PM), I noticed that the pace hadn't slowed - they were at it 24
hours a day.
My curiosity got the best of me yesterday when they brought in the giant
tanks full of liquid nitrogen. LN-2 for the DWP? I parked my car and
played the lookie loo.
It turns out they have a problem with an underground wire. Not just any
wire but a 230 KV, many-hundred-amp, 10 mile long coax cable. It
shorted out. (Lotta watts!) It feeds (fed) power from the Scattergood
Steam Plant in El Segundo to a distribution center near Bundy and S.M.
Blvd.
To complicate matters the cable consists of a copper center conductor
living inside a 16 inch diameter pipe filled with a pressurized oil
dielectric. Hundreds of thousands of gallons live in the entire length
of pipe. Finding the fault was hard enough. But having found it they
still have a serious problem. They can't afford to drain the whole
pipeline - the old oil (contaminated by temporary storage) would have to
be disposed of and replaced with new (pure) stuff which they claim takes
months to order (in that volume). The cost of oil replacement would be
gigantic given that it is special stuff. They also claimed the down
time is costing the costing LA $13,000 per hour. How to fix it and
fast?
That's where the LN-2 comes in. An elegant solution if you ask me.
They dig holes on both sides (20-30 feet each way) of the fault, wrap
the pipe with giant (asbestos-looking) blankets filled with all kind of
tubes and wires, feed LN-2 through the tubes, and *freeze* the oil.
Viola! Programmable plugs! The faulty section is drained, sliced, the
bad stuff removed, replaced, welded back together, topped off, and the
plugs are thawed. I was amazed.
------
The next day:
Last night the DWP held a curbside chat to allay the neighborhood's
fears that they were going to accidentally blow us all up. Apparently
all the vapor clouds from all the LN-2 blowoff had caused a great deal
of concern.
Interesting bits:
The feeder was laid 17 years ago and was designed to have an MTBF of 60
years. There are other similar feeders in use around California, in the
Pacific North West, and some on the east coast. This was the first
failure in the western US. No one out here had any idea how to fix it
so they brought in experts from the east. (NYC has had some faults.)
This link is a very critical part of the LA power grid. Last night the
city engineers verified the $13,000 per hour power cost figure quoted
the day before. (I guess that means they are being forced to buy power
off the grid somewhere else.)
There are actually three center conductors (they had a cross sectional
model to show us). Each is about 3" in diameter with a one inch solid
copper core. Each is wrapped with hundreds of layers of a special
paper. That, in turn, is sheathed with copper and then each one is
spiral-wrapped its entire segment-length with a 1/4 inch bronze "wire".
The three conductors are then twisted together during the pulling
process. The bronze spiral wraps form a kind of linear bushing with
minimal contact area with the inside of the pipe so it's "easy" to pull
each segment. Ha.
Each of the three legs in the feeder carrys 600-800 Amps (depending on
demand) of 230KV three phase power. The ground return is the Santa
Monica Bay. Down at the Scattergood Steam Plant and up in Santa Monica
they have a giant copper anchors out in the bay.
They lay these things in 2000 foot segments. 2000' is the longest
segment they can pull through the steel pipe. The pipe is laid first
and then the internal cable(s) are pulled through. Tensile forces must
be enormous. At each segment joint (splice) there is a very large and
expensive ($100K) underground vault. Future technology may allow them
to go 3000 feet, reducing the number of vaults needed per run, thereby
saving money.
After the feeder was originally built (and the cable pulled) it was
thoroughly evacuated to both leak test and remove any contaminants. It
was flushed with dry nitrogen and then reevacuated. Golden Bear High
Tension Oil was then slowly added while still maintaining a vacuum so as
to "pull" any residual gas contaminants out of the oil and the cables in
the pipe. The pipe, full of oil, is then pressurized to about 200 PSI
for some period of time before it gets powered up. 200 PSI is
maintained during operation to keep any bubbles from forming and to
drive insulating oil into the paper.
At both ends of the pipeline they have 6000 gallon tanks of Golden Bear
lightly pressurized under a blanket of dry nitrogen. There are pumps at
both ends. There is about 100K gallons in the entire pipeline, not
including the 6K gal tanks. Every six hours they reverse the pumps so
the oil oscillates back and forth in the pipe. The pumps only run at 3
gallons per minute but that is enough, over 6 hours, to get the oil in
each 2000 foot segment to go at least a segment or two length in either
direction. This eliminates hot spots in the copper conductors and
spreads the heat out over several thousand feet. A little competitive
pressure is always maintained between the pumps to get the 200 PSI.
They learned the hard way that you simply don't reverse the pumps lest
you get the Golden Bear equivalent of water hammer. The last hour of
every 6 hour cycle is spent slowly reducing the oil velocity down to
zero before you reverse it and then slowly ramp back up in the other
direction.
In between segments, in the vaults, are temperature sensors embedded in
the pipe. These monitor the oil temperature. These are wired to a
computer downtown. Because the oil oscillates, the DWP can track the
temperature gradient along the pipe and get an early indication of the
location of any hot spot problems. They have regularly spaced flow rate
and pressure monitors for the same purpose - detecting and isolating
faults.
Every vault also has a nipple which allows sampling of the pipe oil.
They said you withdraw the oil through a thick membrane with a syringe
(?). This happens monthly on all feeders in the LA area. The samples
are analyzed downtown by a staff of chemists who can relate the presence
of things like acetylene, butane, and benzene in the oil to arcing,
coronas, and so forth. Apparently the oil chemistry is a very good
indicator of the health of the segments.
One of their worst fears, after they open up the pipe, is having a
blowout of the freeze plugs. If they ever run out of nitrogen during
the repair process they'll lose one side of the pipe (or both). Right
now they've got the pipe on each side of the fault dropped down to 80
PSI. They are afraid that if they go any lower in oil pressure any gas
in the oil will come out of solution and cause an explosive expansion.
Not only that, but since there is so much oil embedded in the paper
insulation, any sort of gas bubbling (oil foaming) would shred the
insulation, rendering the entire feeder useless. They say it could take
months to safely let the pressure off to zero. (That is the other
reason ($13k/hr) they cannot afford to drain the whole pipe.)
Even at 80 PSI, if they lose a freeze plug they will have a really big
mess outside the pipeline. The holes they've dug cannot hold 100K
gallons and they're operating on a hill near the beach anyway... (Big
pollution threat for LA basin.) Potentially fatal for anyone around.
Right now they have LN-2 companies on call from San Diego to San
Francisco with contingency plans of all sorts in case there is a major
traffic problem with trucks getting in.
They say the repair could take weeks or more, depending on what they
find when they get inside. They believe the cause of the fault was the
inner conductors slipping downhill inside the pipe and shorting against
a metal flange. Even if that's true they wonder where it slipped to,
and hence, where it may be bunched up down hill.
Finding the fault was a problem in itself. Since this was all new to
them they really didn't know how to start. They tried time-domain
reflectometry equipment but got inconclusive information. They tried
ultrasound and radar but that didn't work. Then they got a thing called
a "thumper" shipped in which got them pretty close. The thumper sends
mondo-amp pulses into one end of the cable. The electromotive force
tends to cause physical displacement of the conductors which you can
hear from the street level. The place where the clicking stops is where
the problem usually is. This got them to the defective segment.
What pinpointed the problem in the end was a bunch of car batteries and
some millivoltmeters. (From one technology extreme to the other.) They
hooked up car batteries to both ends, tapped the cable at several points
(maybe there are taps in the vaults?) and, knowing the drops and
resistance of the cable, got within a few feet of the fault. (I used
to use the exact same technique on memory boards.)
Next came the X-Ray equipment. Sure enough, they can see the cable
shorting against the steel wall of the pipe.
Once all of the repair is done they still have to close it up. How do
you weld a steel pipe with paper insulation inside? Slowly. They have
special heliarc welding equipment and "certified operators" who take 8
hours to weld around one cross section of pipe. They are required to
keep their hand on the pipe no more than 3 inches from the tip of the
welder. If it is too hot for their hand they stop and let it cool.
After all, they can't afford another failure.
- ------
Oct 20, 1989 Update
I am getting all of these bits from a guy named Jim who is the project
manager. He looks kinda like a red neck RWK (Jesus in a hard hat with
a Harley belt buckle). [RWK is Bob Kerns, an ex-Symbolics person,
6'7" tall, skinny, bearded. -- DLW] He is a really great guy. Jim was
one of the splicers on the project 17 years ago when he was working
his way through school. He is a now professional electrical and
mechanical engineer. After having worked his way up through the ranks
at the DWP he is now The Big Boss. He claims to be having the time of
his life - back in the field with one of the biggest challenges of his
career. If we ever recruit a VP of engineering I would hope its
someone like him.
So, what went wrong? Varying load conditions in the three legs of the
3-phase circuit caused tremendously strong and dynamic magnetic field
changes. The electromagnetic forces between the three conductors and
the steel pipe (gack!) cause the conduit to wiggle around inside the
pipe. Over many years (and under the influence of gravity) the thing
slipped and wiggled every which way. Also, due to very slight
diametric temperature gradients, the differential thermal expansion of
a cable that big across causes bending and warping forces. Nobody
ever thought of any of this.
Wiggle alone may not have cause the problem, however. The spices
between cable segments are much larger in diameter than the cable
itself. The steel pipe at these points is much larger than the main
run. So the whole affair get fat and then shrinks down every 2000
feet or so. What really screwed them was failure to put any sort of
clamp at the splices to keep the fat splice from getting pulled into
the narrower main runs. This is what cause the fault.
Jim says the fault lasted 20 milliseconds before breakers tripped.
(The breakers for a wire like this are pretty amazing in their own
right. They use high pressure gas to blow out the arc as the circuit
begins to open. Anything that can cut off this number of megawatts in
20 ms gets my respect.) It blew carbonized oil about 3000 feet down
the pipe to either side of the fault. (Compute velocity...)
They will be removing a long length of cable from the faulted area for
analysis. The entire length will be dissected. Jim says the
insulation they have inspected at so far looks like shredded
cauliflower due to the explosion from the fault and the gas bubbling
in it. (BTW - The insulation consists of 118 layers of paper tape.)
Based on X ray imaging they are going to have to open up 14 of the 23
splices along the 10 mile run. They'll have to drain the pipe to do
so. It will take them 2 months to take the pipeline down
(depressurize and drain). (The oil will be recycled - see below.) At
each of the opened splices they are going to install special aluminum
(non magnetic) collars around the conductors to keep the splices from
getting pulled into the necked-down section of the pipe. These
collars are being specially fabricated now and will be ready in about
a month.
At each splice they have to build a semi clean room to keep dirt,
moisture, worker sweat, and any other contaminants out of the joint
before closing. After all, we're talking a quarter megavolt! They
have special air conditioning and filter units for the vaults. Each
joint will take two months of work. They will get some degree of
parallelism in the phase of the project.
After repairing and replacing the faulted section of cable,
stabilizing all of the splices, and buttoning it all up comes the job
of putting the oil back in. First the pipe is evacuated and then
back-filled with nitrogen etc as I described earlier. After extensive
filtering, the oil is heated to about 230 degrees farenheit. It gets
injected into a vacuum chamber at the temperature thorough hundreds of
spray nozzles. This gets the maximum possible surface area so all the
crap in it boils out into the chamber. The good stuff that's left is
collected and pumped immediately into one end of the pipeline.
Then they power it up and see if it works. If not, they start over
again. I'll keep you posted.
----
12/11/89
The pipeline is now completely drained and filled with nitrogen at
atmospheric pressure. They are still in the process of opening up many
of the splices to install the collars. They originally planned on doing
14 of them but now the number is 17.
The splice where the short happened, and the cable for about 40 feet to
either side of it, has been completely replaced. Engineering prototypes
of the aluminum collars are now installed there and the whole thing is
all welded back together. They built new vaults under the street where
the new splices are. The trucks, men, and their equipment are all gone
and the roadbed has been repaved. They consider the segment where the
short happened "fixed". We'll see...
Now that they verified the assembly of a splice with the new collars in
it (to make sure they had the details right) they are going ahead with
the fab run for the 17 other joints. They won't be done installing them
until mid April. Then they'll put the oil in as described above and
power it up slowly. I don't expect to have much to report until then
and I promise to send an update.
Assuming 8 month down time the cost of the electricity alone will
approach $75 million!
------
[after many queries of "So how did it all work out?"]
... I am sure that you will all get this final message in due time.
You see, I found out yesterday that even the Department of Water and
Power repair crew got copies! It rattled across electronic bulletin
boards around the country and eventually ended up in the hands of a DWP
manager who promptly showed it to the team. Small world. Every time
you turn over a rock you find that we are all connected.
So, here's the scoop:
They are back on line. The failure was attributed to "TMB", short for
Thermal Mechanical Bending. There have been several similar failures
on the east coast but this was the first out here. TMB causes the
cable to wiggle in place due to load surges. This eventually causes
insulation failure due to abrasion against the pipe and separation of
the many layers of paper tape. They repaired the short, put aluminum
collars in most of the joints to hold the splices in place, and have
added a load management scheme to reduce the current
peaks. They powered it up and the darned thing works. Amazing.
I'll impulse them again in a few months to see if there is any news.
Tony Miklos
me good. I was working on a cigarette machine, converting it to accept
dollar bills. It was turned off but I forgot to unplug it. Using the
handy connectors they provided, I grabbed the channel locks and
proceeded to splice the 120 vac wires. It was a tight squeeze and my
sweaty forehead was resting on a large piece of grounded metal. When I
squeezed the pliers, all I saw was a flash of light. It wasn't from a
spark, it was from the electric flowing through my head and out my
hands, passing my eyeballs on the way. It sure lit up those nerve
endings! This isn't to mention the numerous times I've felt 35,000 from
the high voltage in video monitors.
--
Tony
Branko Badrljica
Tony Miklos wrote:
I second that, since one of my experiences was almost exactly the same, only
voltage here is 220V and it wasn't
cigarette machine ;o)
Other occasion worth mentioning might be when as a kid I grabbed some metall
fence with my right arm and trying to reach metallic enclousure of outdoor
lamp with my left arm...
Well, enclosure was under 220V and when I touched it I had the pleasure of
knowing how my scope feels sinewave...
Trust me, it's small when flowing through the wire (in my case hand), then
suddenly it grows so you can see it and then shrinks in order to be able to
slip through other hand errm-wire ;o).
At the time I was certain that what I felt was pure sine and that square
wave or triangle would have different feel at 50 Hz...
Branko
> --
> Tony
Tony Miklos
That reminds me of the time I was standing in a creek (a teenager). A
thunderstorm came up real quick. We were at a slippery part of the
creek. The bottom was mostly clay. So while grabbing onto a fence,
pulling ourselves out of the creek, the lighting hit the fence. Luckily
it hit a half mile away. We did feel one hell of a zap though! No,
there was no sine wave;-) Only two kids running as fast as they could
for home!
--
Tony
lectron...@my-deja.com
Railroad.
Diesel tractor unit in the shop for repairs.
Generator is 600V at 3000A.
Main drive motors disconnected and wires hanging down and shorted.
Mechanics testing the diesel motor at high rpms.
Screwdriver gets dropped and shorts the excitation generator field to
the battery supply.
Full excitation applied to main generator.
Dead short across main generator from the motor wires.
3000 HP diesel engine comes to halt in about two seconds.
People 200 feet away were seeing spots for hours.
--
When you shoot at the messenger you are admitting
that you have lost the argument.
David Milne
http://www.cs.auckland.ac.nz/~pgut001/misc/mercury.txt
It was reported that they said that "Sumeone had been fuddling wuth the swutch."
gorgon...@my-deja.com wrote:
> IT WOULD BE NICE TO HEAR STORIES ABOUT BIG SHORT CIRCUITS. NO, NOT
> LITTLE SPARKS WHEN YOU SCREW UP YOUR CAR STERO INSTALL- I MEAN BIG
> HAIRY SPARKS AND JOLTS THAT SCARED THE CRAP OUT OF YOU!
>
> STUFF LIKE:
>
> POWER COMPANY 'FAULTS', MASSIVE BATTERY BANK SHORTS, 3RD RAIL
> VIOLATIONS, POLE PIG FIRES, TOOLS ACROSS BUSBARS, TRANSMITTER
> ARCING, TESLA PROJECTS GONE AWRY, MEGA-AMP MELTDOWNS,
> PENNY-IN-THE-FUSEBOX ANTICS, MOTOR-GENERATOR MISHAPS, MISWIRED
> MAINS, ELECTRIC MAYHEM, POWER LINES DOWN, BREAKERS THAT WON'T
> TRIP, HIGH-VOLTAGE CRAZINESS, ETC.
>
--
Regards
David Milne
ICQ 37590068
John Popelish
Bill, you sound like you are enjoying the memory of this event just
because it happened to be a female who made this boo boo. You sort of
imply that men have never made stupid mistakes like this.
You are a worthwhile person, and, doggonit, people like you. ;-) No
need to prop up your male ego and belittle half of the population just
to tell a scary tale when you can belittle all of us with equal
justification.
--
John Popelish
Calvin Henry-Cotnam
>
>IT WOULD BE NICE TO HEAR STORIES ABOUT BIG SHORT CIRCUITS.
Short circuits can turn out to be a bit of a surprize for some
people -- thinking that since a circit is protected by a 15 A
fuse or circuit breaker, some think the current flow could not
possibly go any higher than that. Unfortunately, fuses and circuit
breakers are not clamping devices, but rather thermal devices that
require a period of time, albeit a short period, to break the
circuit. In the meantime, the generation capacity of a heck of a
lot of sources are on the supply side to push current through the
short.
Most switchgear and service equipment has peak current ratings
in the 100- to 400-thousand ampere range! The reasons for this
was demonstrated with a story by an electrical inspector running
a new-code seminar I attended a couple of years ago.
In the story, he told of an electrician who needed to measure
the size of a cartridge fuse in a panel. The fuse had been
removed and he was holding a rule up to measure the distance between
the fuse lugs.
Call it forgetfulness, or just simple stupidity, but this guy was
using a steel rule for this task.
As the inspector said, "as we were interviewing him from his hospital
bed..."
He did say they never found a trace of the rule.
I do have a second story. A few years back I was involved in the
installation of computer-controlled heating and A/C equipment for
some remote sites for the phone company. In a telephone central
office (CO), the phone equipment operates off of lead-acid batteries.
Not quite like your car battery, the CO battery consists of 24 two-volt
cells to give the 48 volts needed for the phone system. Each cell
is about two feet high and about a foot wide and deep.
A very thick copper bus carries the power from the cells to the
equipment frame. When doing work, one is supposed to place a tarp
over the cells and the power bus. Carrying around conduit, you
don't want to short that bus.
I was told of a story of a painter who did not tarp the equipment.
While painting the ceiling, he accidently placed his metal paint
tray across the bus. Fortunately for him, the thin metal tray
melted quickly, sort of like a fuse link. If it didn't, the only
significant resistance in the circuit would have been the cells'
internal resistance: meaning the fluid would get hot quickly and
begin to boil, causing an explosion.
--
Calvin Henry-Cotnam | "Nothing quite livens up a suburban
DAXaCK associates | neighbourhood like a driveway boasting
Richmond Hill, Ontario, Canada | plastic milk crates loaded with crap."
http://home.ica.net/~calvinhc | -- John Oakley, radio talk-show host
-------------------------------------------------------------------------
NOTE: if replying by email, remove the capital letters!
John Barry
Okay, time for a 440v - 3ph story. Our company built a large
surface-preparation machine for a big tool company in Arkansas, shipped the
machine in pieces for people in AK to assemble. Sent me out there for
startup.
Everything seemed in order, so we progressively fired up all the electrical
devices from the main panel. One big blower motor's starter/overload kept
tripping. Shortly we found flexible conduit with its feed wires pinched,
fixed that, and fired it up again.
Electrical panel was about 10' from machine axis, with its back to the
machine, to pass conveyor. I was behind panel. Local electrician then
started up various devices, with panel door open. On starting the blower
(above mentioned), scene was like something from "The Ten Commandments"-
awesome light and boom, like lightning. Ralph, the electrician, was dazed
for some time from the light and stray currents passing through his parts.
(He did not touch panel devices, either.) Part of the overload device had
gotten carbon-tracked earlier, and now went out in blaze of glory.
Truly a "more-than-one-beer" deal for Ralph, later.
Regards,
John
Terry Kennedy
> I do have a second story. A few years back I was involved in the
> installation of computer-controlled heating and A/C equipment for
> some remote sites for the phone company. In a telephone central
> office (CO), the phone equipment operates off of lead-acid batteries.
> Not quite like your car battery, the CO battery consists of 24 two-volt
> cells to give the 48 volts needed for the phone system. Each cell
> is about two feet high and about a foot wide and deep.
>
> A very thick copper bus carries the power from the cells to the
> equipment frame. When doing work, one is supposed to place a tarp
> over the cells and the power bus. Carrying around conduit, you
> don't want to short that bus.
Generally, all but the smallest strings use horizontal-terminal cells
these days. It's normal practice to install the factory-provided plastic
covers over the cell terminals, as you can see in this picture:
http://www.new-york.net/pics_nyc_pop/nyc_pop_022.jpg
> I was told of a story of a painter who did not tarp the equipment.
> While painting the ceiling, he accidently placed his metal paint
> tray across the bus. Fortunately for him, the thin metal tray
> melted quickly, sort of like a fuse link. If it didn't, the only
> significant resistance in the circuit would have been the cells'
> internal resistance: meaning the fluid would get hot quickly and
> begin to boil, causing an explosion.
There have been some rather spectacular incidents with telco battery
plants over the years. Some are silly mistakes like the one you relate,
while others come from people applying "red = positive" rules to telco
battery plants, and similar mistakes.
Terry Kennedy http://www.tmk.com
te...@tmk.com Jersey City, NJ USA
Donald Borowski
ago when we had a once-in-a-century ice storm. A whole day of freezing
rain brought down some power lines directly, and many others via falling
trees and limbs. I was at work that day, and watched some power lines
dance on the ground along side of a road. When I got home, I was without
power, and in the silence I could hear the hum of arcs from the power
lines going down. The night sky would occasionally light up like during
thunderstorms, except that the light would keep going for much longer.
The other distinct memory was the sound of what I though were shotguns
being fired in the distance. Turned out it was trees snapping and
falling over.
--
Donald Borowski
Agilent Technologies, Spokane PGU
Markus Imhof
learning as electrician in a large chemical plant. This plant then had
(and still has) its own steam generator, both for steam and electricity,
and in a size that could easily supply a medium city. Buying electricity
from the grid apparently is too expensive on this scale.
Well, one of the generators was taken off line for servicing, and had a
new control panel installed. On these control panels, there is a phase
indicator which shows the phase difference between the generator and the
grid. Installation was complete, the generator was fired up and
phase-adjusted so it could be switched to the grid. When pressing the
decisive button (not by my father, btw), the proverbial infinite force
(the generator) hit the immovable object (the grid) with a loud bang.
What had happened: in installing the phase indicator, two wires were
crossed, resulting in a 180 degrees phase difference between what should
be shown in thory and what actually was shown on the indicator.
Therefore, instead of connecting the generator in phase it was connected
180 degrees out of phase - with a few Megawatts on the turbine (and the
inertia of all that rotating stuff) pushing the generator in one
direction and a few Megawatts more from the grid pushing in the other
direction.
Bye
Markus
Beau Schwabe
and while taking a stroll through the salvage yard in back, I came
across a HUGE lead-acid battery rated in Joules instead of Volts or
AH. Rated at 30KJoules..... (after the smoke clears..... Hmmmm, I
wonder where I laid those pair of pliers ...grin)
Beau Schwabe (Mask Designer)
National Semiconductor Corporation (Network Products Division)
500 Pinnacle Court, Suite 525 Mail Stop GA1 Norcross, GA 30071
Dave Gower
<gorgon...@my-deja.com> wrote in message
news:906p6g$23$1...@nnrp1.deja.com...
> IT WOULD BE NICE TO HEAR STORIES ABOUT BIG SHORT CIRCUITS.
Looks like your CAPS LOCK BUTTON GOT STUCK. Hit it and it turns off. (I'm
serious. This is the Internet equivalent of shouting, and is just as
distracting).
My best (worst) experience was during the Great Canadian Ice Storm of
January 1998. I was upstairs in the computer room on the Internet. The
weather forecasters were warning of serious power failures (although no one
knew how serious they were going to be). It was early evening.
The power started to fluctuate, so I figured this is it. I got up and looked
out the window which faces north. And there coming up my country road was a
series of brilliant fireballs, getting closer and closer. They lit up the
sky. Then everything went dark for miles around (and was still dark a week
and a half later, by the way).
A couple of days later when the road had been cleared enough that I could
drive up it was evident what caused the fireballs. Over 30 wooden power
poles, brand new ones, had been snapped like toothpicks by the combination
of wind and ice buildup (which was over 4 inches thick). Many had been
broken in several places.
Bill
>
> Bill, you sound like you are enjoying the memory of this
> event just because it happened to be a female who made
> this boo boo. You sort of imply that men have never made
>
I thought I might get in trouble for that one! Sorry. I thought about
changing the story from "female" to "inexperienced technician", but then
thought I would tell it like it happened and take my lumps. By the way, I
have met some females that can run circles around most other people in the
computer field, but this particular person had no experience and should
never have been hired. They hired her just to be an "equal opportunity
employer". And you are correct that many men have made similar or worse boo
boos, and to be fair, there is the story of the *guy* that was digging a
hole with a backhoe and dug up and cut a main phone cable that serviced an
alarm company monitoring center. (Did not get underground cables marked
first.) Within 3 minutes there were cop cars everywhere. That guy was not
having a good day to say the least.
niko...@my-deja.com
test drive the newly introduced XJ6. The car was lined up with other
new Jags. The battery was dead, we sat in the car while the salesman
opened the hood and hooked up a huge charger/starter. He flipped the
switch and the battery exploded showering several new cars with hot
acid, molten lead and burning tar.
Despite the free fireworks we bought another Ford...
Stephen
In article <906p6g$23$1...@nnrp1.deja.com>,
gorgon...@my-deja.com wrote:
> IT WOULD BE NICE TO HEAR STORIES ABOUT BIG SHORT CIRCUITS. NO, NOT
> LITTLE SPARKS WHEN YOU SCREW UP YOUR CAR STERO INSTALL- I MEAN BIG
> HAIRY SPARKS AND JOLTS THAT SCARED THE CRAP OUT OF YOU!
>
> STUFF LIKE:
>
> POWER COMPANY 'FAULTS', MASSIVE BATTERY BANK SHORTS, 3RD RAIL
> VIOLATIONS, POLE PIG FIRES, TOOLS ACROSS BUSBARS, TRANSMITTER
> ARCING, TESLA PROJECTS GONE AWRY, MEGA-AMP MELTDOWNS,
> PENNY-IN-THE-FUSEBOX ANTICS, MOTOR-GENERATOR MISHAPS, MISWIRED
> MAINS, ELECTRIC MAYHEM, POWER LINES DOWN, BREAKERS THAT WON'T
> TRIP, HIGH-VOLTAGE CRAZINESS, ETC.
>
> LET'S HEAR SOME GOOD ONES AND THEN I'LL POST SOME TOO. WHO
> HAS THE BEST TALES TO TELL? ANY YOU EX-MILITARY GUYS HAVE SOME
> GOOD STUFF TO SHARE?
>
> GORGONZOLA 57
> OVER AND OUT.
Bernard Green
[1]
"In the days of power cut in the UK a company bought a large 3 phase
generator to power the machinery, They had a 50 Hz to 400Hz 440v 3 phase to
110v 3 phase convertor to drive the very high speed tools used for trimming
laminates and othe timber work. The convertor was a motor generator set of
about 5 Kw/
As a test of the new generator the motor of the converter was switched from
the mains to the already running generator. Unfortunately the phase rotation
was reversed. 400 Hz generator shaft ended at 45 degree to the shaft of the
motor. Messy.
[2]
The contact pads on contactors for a DC powered copying lathe were getting
worn so the new "electrician" was asked to find replacements and fit them.
He could only find pads about twice the diameter which would only fit if the
cooling spirals were removed. As the old pads never got hot this wouldn't be
a problem. Especially as the new pads had 4 times the area.
The lathe was started and the tool carrier was moved towards the chuck. At
the required place the operator stopped the carrier but it kept moving
jerkily. Hitting all stop made no difference. By the time the operator had
pulled the main supply breaker the tool carrier had hit the chuck.
The spirals were the electromagnetic arc snappers. Without them the
contactors would arc and the motors run on the arc current.
Short lived electricians job wise
Bernard
Victor P. Dura
>Dead short across main generator from the motor wires.
>3000 HP diesel engine comes to halt in about two seconds.
>People 200 feet away were seeing spots for hours.
Wow! That was exciting.
--
Visit the Shoals Symphony Orchestra Web site at
http://www.dreamwater.net/music/shoalssympho/
J Kelly
being present for one of these:
The UHF TV transmitter that I work on has a 25KV 20A power supply for
the Klystron beams. The Klystrons happen to be water cooled. I guess
when you get a leak inside the transmitter it is like having God snap
his fingers.. Indoor lightning!
I keep hoping I never have a water leak in there, but I know it's just
a matter of time..
Bernie Hunt
Bernie
John Barry <j...@zedak.com> wrote in message
news:mbPV5.85$xH5....@dca1-nnrp2.news.digex.net...
Not Me
In the early 80's I spent a lot of time at a large sewage treatment
plant doing an instrumentation startup. While I was there one
brilliant worker decided to wash down a 480 volt panel with a hose.
Made a hell of a mess in the panel, and got his attention. At the same
plant, another worker decided to test a ground fault interruptor on a
480 volt panel by using a piece of very large gauge copper ground wire
to short out one of the legs to ground (he apparently didn't realize
what the word 'test' on the interruptor meant). Needless to say, there
was a very bright flash and bang, and the worker was thrown across the
room. It did prove the interruptor worked, though.
Terry Miller
> LITTLE SPARKS WHEN YOU SCREW UP YOUR CAR STERO INSTALL- I MEAN BIG
> HAIRY SPARKS AND JOLTS THAT SCARED THE CRAP OUT OF YOU!
I have two.
First was while working as an Engineer on a sea-going tug. We had
just been released from dry dock where we had been on shore power.
That's when an electrician brings a big cable, carrying 480V, and
affixes it to the busses of the main power panel. As we had been at
sea for a week, it was time to swap generators so the one that was
running could be serviced. After synconizing them, I threw the
breaker to connect the "cold" generator to the "hot" generator, and
tremendous sparks blew out of the side of the panel. A little
unnerved, I threw the breaker to disconnect the "hot" generator from
the grid. Sparks flew again.
I reported all this to the Chief Engineer, who just nodded. Next
shift, I went into the engine room to find the Chief flat on his back
and out cold. He woke up pretty quick with smelling-salts...and just
started cussing, well, like a sailor. All he had done was touch the
power panel (which I NEVER did). Later we found that the electrician
had simply cut the shore cable and replaced the panel. He had left
enough of the cables to just contact the metal panel door
intermittently.
Next was at college, in preparation for a full-blown dorm party. We
had this "I know more than you" kid who volunteered to make a panel
board to run stereos, lights, etc. Basically, he had one lamp-sized
120V zipchord powering four 500 watt spots, several motors with
spinning color disks, and two 400 watt stereos turned up full blast.
All went well at first...only one stereo at a time, and never more
than two spots at a time...then he got ambitious. Both stereos were
tuned to the same station and run, and he got to playing the spots
like a keyboard. When he hit them all at the same time...out went the
lights, but not before the stereos blew and the room filled with
smoke. And that's not all.
Basically, he had run the plug so close to breaker-trip for so long,
that the in-wall wires were hot. When he goosed it, he melted a wire,
which fell across the other, creating 220V at the wall outlets on the
girls' side of the dorm. Clocks, stereos, hot plates, etc...anything
that was running...fried instantly. The few girls in their rooms at
the time just thought that "it broke," but the next morning, when the
lounge TV blew up, we ran that kid up a flagpole! The University paid
all damages, then assessed the kid $6500...and banned him from the
dorms.
Terry Miller, PE
Mark Fergerson
>
> [[ This message was both posted and mailed. ]]
>
> In article <906p6g$23$1...@nnrp1.deja.com>, <gorgon...@my-deja.com>
> wrote:
>
> > IT WOULD BE NICE TO HEAR STORIES ABOUT BIG SHORT CIRCUITS.
>
> Here's my favorite:
>
> Date: Wed, 27 Sep 89 10:27 PDT
> From: "Thomas L. Mc Mahon" <t...@riverside.scrc.symbolics.com>
> Subject: Cuts and jumpers (on a different scale)
> To: Hard...@riverside.scrc.symbolics.com
>
> [Not quite the right mailing list but close. If you don't care about
> megawatts, bus bars bigger than your wrist, things that cause ground
> loops out to Hawaii, or big hairy construction projects hit D now.]
Excellent story about the hazards of scaling; most things we want to
build are tried "tabletop" first and then done full-scale. It would
seem that there can be a few unforeseen difficulties, to put it
mildly.
I'm in the middle of the opposite process; scaling a standard Tesla
coil setup _down_ physically (which means higher frequency) and it's
expanding my education considerably.
Mark L. Fergerson
Ralph & Diane Barone
>IT WOULD BE NICE TO HEAR STORIES ABOUT BIG SHORT CIRCUITS. NO, NOT
>LITTLE SPARKS WHEN YOU SCREW UP YOUR CAR STERO INSTALL- I MEAN BIG
>HAIRY SPARKS AND JOLTS THAT SCARED THE CRAP OUT OF YOU!
>
>STUFF LIKE:
>
>POWER COMPANY 'FAULTS', MASSIVE BATTERY BANK SHORTS, 3RD RAIL
>VIOLATIONS, POLE PIG FIRES, TOOLS ACROSS BUSBARS, TRANSMITTER
>ARCING, TESLA PROJECTS GONE AWRY, MEGA-AMP MELTDOWNS,
>PENNY-IN-THE-FUSEBOX ANTICS, MOTOR-GENERATOR MISHAPS, MISWIRED
>MAINS, ELECTRIC MAYHEM, POWER LINES DOWN, BREAKERS THAT WON'T
>TRIP, HIGH-VOLTAGE CRAZINESS, ETC.
>
>LET'S HEAR SOME GOOD ONES AND THEN I'LL POST SOME TOO. WHO
>HAS THE BEST TALES TO TELL? ANY YOU EX-MILITARY GUYS HAVE SOME
>GOOD STUFF TO SHARE?
>
>GORGONZOLA 57
>OVER AND OUT.
>
>
>Sent via Deja.com http://www.deja.com/
>Before you buy.
OK, here's a few "Big Bang" stories. All names have been changed to
protect the innocent...
1) A disconnect switch that burned open on a circuit carrying 1200 A DC at
280 kV. After the incident, I noticed some aluminum on the ground that had
melted from the switch and fallen into the gravel. I grabbed at it with a
pair of pliers and pulled a lump of gravel and aluminum about 2 feet across
out of the ground.
2) A hydro plant about 40 - 60 years ago where the breaker generator was
tripped, but the water supply to the turbine wasn't shut off. The unit
went overspeed to the point where the rotor flew apart from centrifugal
force. The picture I have shows an enourmous hole blown through the outside
wall of the power plant. Inside the plant, it looked like a bomb had gone
off. I'm guess the pole pieces of the rotor were about 2 feet long, 1 foot
wide and 1 foot thick. Imagine what a chunk of iron that size does when it
finally lets loose from the shaft.
3) A synchronous condensor (essentially a synchronous motor without a load,
used to help regulate the voltage on the power system) that was
accidentally connected to the power system out of synchronism to the main
grid. The unit was rated at 50 MVA (that's million Volt-Amps) and the bus
it was connected to had a short circuit capacity of 80,000 A at 12,500 V.
I'm pretty sure all the capacity of that bus was used when the breaker was
closed. The condensor had differential protection, but what went into the
unit was also coming out the other side, so the protection didn't trip.
The unit finally tripped off line after part of the stator winding melted
and shorted to ground.
4) Another synchronous condensor had a unique startup mechanism. A large
variable speed drive (VSD) was used to spin the unit up (as a motor) past
synchronous speed, then it would be disconnected from the variable speed
drive and synchronized to the system as it slowed down. Unit speed was
sensed from a small permanent magnet generator (PMG) attached to the shaft.
One day, some of the rectifier diodes in the PMG went south and the PMG
only put out 1/2 or 2/3 the voltage it used to. On the next startup, the
VSD spun the unit up until it got the right voltage out of the PMG (150 or
200% of rated speed) and then tried to synchronize. The sync attempt
failed, so the VSD was again connected and the unit spun up again. On the
second or third startup attempt, the rotor decided it had had enough of
this and let go. The pole pieces on this particular machine weighed about
5 tons each, and when they came off of the shaft, they blew right through
the stator. The stator was built (like a transformer) of numerous thin
iron laminations. These laminations were broken apart by the force of the
impact and rained from the sky (like razor blades, an eyewitness said).
5) A technologist troubleshooting an exciter (essentially a very high
current DC source) for a turbine while the turbine was running. Something
happened and a capacitor blew up in the exciter. Unfortunately for the
tech, when the capacitor blew up, the can exploded and wrapped around the
fuse. The arcing continued inside the exciter
Duane Hague
> IT WOULD BE NICE TO HEAR STORIES ABOUT BIG SHORT CIRCUITS. NO, NOT
> LITTLE SPARKS WHEN YOU SCREW UP YOUR CAR STERO INSTALL- I MEAN BIG
> HAIRY SPARKS AND JOLTS THAT SCARED THE CRAP OUT OF YOU!
>
> STUFF LIKE:
>
> POWER COMPANY 'FAULTS', MASSIVE BATTERY BANK SHORTS, 3RD RAIL
> VIOLATIONS, POLE PIG FIRES, TOOLS ACROSS BUSBARS, TRANSMITTER
> ARCING, TESLA PROJECTS GONE AWRY, MEGA-AMP MELTDOWNS,
> PENNY-IN-THE-FUSEBOX ANTICS, MOTOR-GENERATOR MISHAPS, MISWIRED
> MAINS, ELECTRIC MAYHEM, POWER LINES DOWN, BREAKERS THAT WON'T
> TRIP, HIGH-VOLTAGE CRAZINESS, ETC.
>
> LET'S HEAR SOME GOOD ONES AND THEN I'LL POST SOME TOO. WHO
> HAS THE BEST TALES TO TELL? ANY YOU EX-MILITARY GUYS HAVE SOME
> GOOD STUFF TO SHARE?
>
> GORGONZOLA 57
> OVER AND OUT.
>
>
> Sent via Deja.com http://www.deja.com/
> Before you buy.
>
qualifies:
Back in pre-PC minicomputer days about 1979, a military lab had a
custom graphics display system made (1024x1024x16 resolution with 16:24
color mapping, hot stuff in those days). But the system has noise
problems. An older engineer assigned to solve the problems was an analog
guy who had re-treaded himself into digital. His basic approach was to
locate each noisy signal and put a ferrite core on each wire-wrap wire.
At one point, he decided that he needed to "Input AC Voltage Margin" the
system which was basically 120VAC, 3 phase Wye, & 60 Hertz standard at 20
amps per phase. However, he could only find a 400 Hertz Triac. He
cleverly figured out an analog ciruit to "rotate the impedance pole" and
went scrounging for parts. Here is where things started to go wrong. He
found a big electrolytic capacitor that was "twice the line voltage" and
forgot that he needed "twice the peak voltage". For a week, his circuit
worked. During this time management observed his exposed hot wires and
demanded that he make the setup "safe". This he did by putting a
cardboard box over the Triac which was ridiculus but may have saved his
eyes. Because the next day, that capacitor failed and the Triac
instantly reverted to "400 Hertz" mode while carrying 20 amps of 3-phase
60 Hertz. The resulting "BANG" was heard six rooms away and plunged most
of the building into darkness and popped every circuit breaker on a 200
amp 3-phase feedline back into the transformer vault. While the engineer
only needed a change of pants, the graphics display was unharmed.
However, we found that we had acquired an empty Triac frame and a copper-
plated cardboard box!
Tom Miller
> | IT WOULD BE NICE TO HEAR STORIES ABOUT BIG SHORT CIRCUITS.
It's around 5:30 PM and I'm just getting home from work. It's dark out
already (it's almost mid-November in 1965). I open the door to my
apartment in New York City, reach for the light switch by the door,
and flick it on. The hall light comes on for a second, flickers a few
times, and then goes off. I'm thinking, do I know where the heck the
fuse box is? Do I have any spare bulbs? I look across the dark
apartment and through the window on the other side of the room and
watch the lights outside go out everywhere. I later find out that 30
million of us are in the dark, from Ontario to New Jersey. For a
brief second I think I am somehow responsible for this.
----------------------------------------------------
"Trudy is Beauth, Beauth, Trudy"©
[To send me an email, remove xx from my address]
Mark Fergerson
Tesla coil; I won't tell any Tesla spark stories because you _expect_
to get zapped by them.
However...
At age 7 I went into our garage and reached, without looking, for
the light switch (the garage had been built before electrification and
was apparently subsequently wired [by a plumber, I'd guess] for 220).
The switch was one of those ancient rotary ceramic-bodied jobs with
exposed contacts, no box. I woke up about 15 min. later, half-sitting
up on the garage door 10 ft. away, vision full of pretty purple
whirlies. I decided not to tell anyone for fear of a whuppin. No big
deal, but I was young yet.
At age 14 a kindly neighbor decided to "Elmer" me in the fine arts
of radio and general electricity, since I'd told him about the switch
incident and he was impressed that I hadn't died of fright. Among
other things, he showed me the (then safe, remember grounded chassis?)
trick of putting your _right_ elbow on the chassis of a TV set and
gauging the 2nd anode voltage by drawing a spark with the extended
fingertip. Later, while showing my sister this trick, I sneezed. I
woke up across the room a few seconds later with more pretty purple
whirlies, my sister screaming fit to wake the dead. Luckily, my folks
weren't home. The TV was unharmed, BTW.
In Air Force Tech School, I went to disconnect a generator set from
the load bank, one sweaty hand on the load bank enclosure, the other
on the "donkey dick". Gen set was gas-turbine-powered unit putting
around 14,000 KW into the load bank. I forgot to hit the unload switch
first. I think I remember the blue flash and the bang, but I could be
fabulating that because I was told it happened. I woke up about 20
feet away a few seconds later (yes, pretty purple etc. present and
accounted for) with the rest of the class about equally divided
between laughing hysterically and staring in shock. Fortunately for me
the instructor was in the can at the time. No equipment damage then,
either. That Mil Spec stuff used to be built truly idiot-proof.
Then there was the time I needed to relieve myself in my uncle's cow
pasture. It was getting dark, and nobody'd thought to warn the city
boy about electric fences. I don't think I lost consciousness
technically speaking, because the next thing I recall is standing
about thirty feet away with my cousin laughing so hard he couldn't
breathe, asking between gasps if I was related to Superman. He hadn't
known I could fly...
If I keep this up I expect I'll eventually copper-plate my glasses,
too.
Mark L. Fergerson
Ben Franklin VI
"First liar has no chance."
<G>
story =
Webster: an incredible tale told as true
First appeared in 1795
=
=
=
=
=
=
=
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=
=
=
preceeded by cock and bull <G>
Big short circuit stories?
Are the stories Big/little or Short/long?
Ben
Subject: Big short circuit stories?
From: gorgon...@my-deja.com
Date: 11/30/00 5:51 PM Central Standard Time
Message-id: <906p6g$23$1...@nnrp1.deja.com>
<IT WOULD BE NICE TO HEAR
<GORGONZOLA 57
<OVER AND OUT.
None preaches better than the ant, and she says nothing. B FRANKLIN, Poor
Richard's Almanack, 1736.
Quality is remembered long after price is forgotten. Ben VI
The bitterness of poor quality remains long
after the sweetness of low price fades.
Ben Franklin VI
Victor P. Dura
wrote:
>It's around 5:30 PM and I'm just getting home from work. It's dark out
>already (it's almost mid-November in 1965). I open the door to my
>apartment in New York City, reach for the light switch by the door,
>and flick it on. The hall light comes on for a second, flickers a few
>times, and then goes off. I'm thinking, do I know where the heck the
>fuse box is? Do I have any spare bulbs? I look across the dark
>apartment and through the window on the other side of the room and
>watch the lights outside go out everywhere. I later find out that 30
>million of us are in the dark, from Ontario to New Jersey. For a
>brief second I think I am somehow responsible for this.
You $^&#%%&@$% bum!! So you're the quy who did that!!! I was on my
way home from work stuck in traffic in Queens when all the traffic
lights (and everything else) went out. It took me 3-hours to complete
what should have been a 15-minute drive.
I'm going to turn you in to Con Ed. I'll bet you owe them big time for
that one. Wha't your mailing address so they can send you the bill?
Next time turn on that light switch *very very* slowly.
Owen Lawrence
>up on the garage door 10 ft. away, vision full
>woke up across the room a few seconds later with
>fabulating that because I was told it happened. I woke up about 20
>feet away a few seconds later (yes, pretty
>technically speaking, because the next thing I recall is standing
>about thirty feet away with my cousin laughing
Forget about short circuits. I'm interested in all of these teleportation
experiments you've been doing!
- Owen -
RaY
subway.She got down on her knees to give me head.As she unziped my jeans
and pulled by shorts down,My brass balls swung down,hitting the third
rail,and frying her lips to my cock.
George H. Patrick, III
> IT WOULD BE NICE TO HEAR STORIES ABOUT BIG SHORT CIRCUITS. NO, NOT
> LITTLE SPARKS WHEN YOU SCREW UP YOUR CAR STERO INSTALL- I MEAN BIG
> HAIRY SPARKS AND JOLTS THAT SCARED THE CRAP OUT OF YOU!
>
When I was in the Navy 20+ years ago, I was stationed at a shore
communications station overseas, where the power supplied to the base
was very unreliable. The station had three 440V, 400KW emergency
generators, driven by LARGE diesel engines (about 6 ft tall and 10 ft
long, not including the generator itself.)
We had a power flop one night, and as the junior guy I had to stay in
the generator room to make sure the generators didn't catch on fire,
run out of fuel, or get stolen (well, they called it "fire and
security watch"). The local power came back and the watch chief came
down to sync the generators and switch back to the local power, an
automated process thet usually worked quite well.
Everything went well until time came to switch out the last generator
and shut it down. At the point where the generator was synced and thw
power was supposed to switch over, the switch failed to disconnect the
generator from the outside power bus. The generator control system
didn't care, it started to shut the diesel down anyway. That whole
generator started to literally bounce on it's base as it got further
off frequency, until the switch (rated at 1000A) failed and shot
sparks and molten metal across the room.
Luckily, nobody was hurt but I still don't know what was worse, the
chief cussing or the arcs 'n sparks (8^D
--
+--------------------------------+----------------------------------+
| George H. Patrick, III | Resources for PCB Designers on |
| gpat...@aracnet.com | the Web - The Designer's Den |
| George.H...@tektronix.com | http://www.aracnet.com/~gpatrick |
+--------------------------------+----------------------------------+
| Take what you like and leave the rest... My opinion ONLY. |
+-------------------------------------------------------------------+
RaY
Ralph & Diane Barone
bar...@mdi.ca (Ralph & Diane Barone) wrote:
>In article <906p6g$23$1...@nnrp1.deja.com>,
>gorgon...@my-deja.com wrote:
>
>>IT WOULD BE NICE TO HEAR STORIES ABOUT BIG SHORT CIRCUITS. NO, NOT
>>LITTLE SPARKS WHEN YOU SCREW UP YOUR CAR STERO INSTALL- I MEAN BIG
>>HAIRY SPARKS AND JOLTS THAT SCARED THE CRAP OUT OF YOU!
>>
>>STUFF LIKE:
>>
>>POWER COMPANY 'FAULTS', MASSIVE BATTERY BANK SHORTS, 3RD RAIL
>>VIOLATIONS, POLE PIG FIRES, TOOLS ACROSS BUSBARS, TRANSMITTER
>>ARCING, TESLA PROJECTS GONE AWRY, MEGA-AMP MELTDOWNS,
>>PENNY-IN-THE-FUSEBOX ANTICS, MOTOR-GENERATOR MISHAPS, MISWIRED
>>MAINS, ELECTRIC MAYHEM, POWER LINES DOWN, BREAKERS THAT WON'T
>>TRIP, HIGH-VOLTAGE CRAZINESS, ETC.
>>
>>LET'S HEAR SOME GOOD ONES AND THEN I'LL POST SOME TOO. WHO
>>HAS THE BEST TALES TO TELL? ANY YOU EX-MILITARY GUYS HAVE SOME
>>GOOD STUFF TO SHARE?
>>
>>GORGONZOLA 57
>>OVER AND OUT.
>>
>>
>>Sent via Deja.com http://www.deja.com/
>>Before you buy.
>
**** Oops, posted early by mistake. Continuing... ***
, since there was nothing to interrupt the current. As the arc spread,
more and more circuitry got "involved", until the entire exciter was
engulfed. At this point, the tech decided to leave the scene QUICKLY.
Unfortunately, the only way out was PAST the exciter. As he put his arm
over his eyes and ran past the exciter, he realized he could see the bones
in his arm. Finally, the exciter transformer breaker tripped to clear the
fault. Returning to the scene, he discovered that the entire cabinet was
empty. All the circuitry had vaporised and the cooling fans had blown the
vaporized components through the exhaust vent and out of the building.
Mark Fergerson
>
> >exposed contacts, no box. I woke up about 15 min. later, half-sitting
> >up on the garage door 10 ft. away, vision full
> >woke up across the room a few seconds later with
> >fabulating that because I was told it happened. I woke up about 20
> >feet away a few seconds later (yes, pretty
> >technically speaking, because the next thing I recall is standing
> >about thirty feet away with my cousin laughing
>
> experiments you've been doing!
Discontinued due to insurmountable targeting difficulties (the
purple whirlies make it impossible to see where you're going to
land)... ;>)
Mark L. Fergerson
Paul Hovnanian Ž
From time to time we had to take substation transformers out of service
for maintenance. To do so, we connected a portable transformer
(mounted on a trailer) to supply the local distribution.
These portable transformers are rated at 10 or more MVA and can
be jumpered for multiple input/output voltages. They are also
equiped with primary and secondary side disconnects, lighning
attesters, etc. We ordered one to be connected for 66kV primary
12.5kV secondary and proceeded to connect it to the local 66kV
line. The lighning arresters consisted of 3 stacks of 3 20kV
arresters in series. Although the transformer primary had been
properly jumpered for 66kV, the arresters had been jumpered
for previous use on a lower voltage circuit by jumpering two of the
three units on each phase to ground. Nobody noticed (they were
inside a caged enclosure).
When the primary switch was closed, all three 20kV arresters
failed rather spectacularly, kicking a fireball a few hundred feet
into the air and throwing smoking porcelain everywhere. I was
standing about 50 feet away (soon to be a lot farther). Within a
second or so, the transmission station breaker (about 20 miles
away) tripped open. After the fault cleared and the maintenance
crew stopped running, we stood and stared at the mess. For about 10
seconds. Then the transmission line breaker re-closed and we got
a second fireball.
--
Paul Hovnanian | (here) mailto:hovn...@bcstec.ca.boeing.com
Software Conflagration | (there) mailto:Pa...@Hovnanian.com
Control | (spam) mailto:postm...@mouse-potato.com
-----------------------+---------------------------------------------
Power corrupts. And atomic power corrupts atomically.
Charles Edmondson
Several year ago, I worked in the Palm Desert, CA. central office. I came in
at 3:30 one day, and my boss walks over, hands me a box of fuses, and says to
go out to the 1000 palms office. I go, get my tools, find the keys to the
truck, and then my boss walks by and asks me what I am doing still being
there! So I get under way.
When I arrive, a third level manager RUNS out to my truck, and gets the
fuses! Wondering what in the world could get this guy moving beyond a
leisurly saunter, I decide to go in and see what is happening...
Seems a contractor had been instructed to tighten the bolts on the buss bars
over the batteries, and didn't have the sense to wrap his socket wrench with
electrical tape. It slipped from his hands, and landed across the main 49VDC
buss below him. (Fortunately for him, it was below him. Otherwise, there
would have been an ambulance there first!) He had taken out every fuse in
the power supplies for the batteries and brought the entire office down.
While they have spare fuses, they don't have that many fuses, therefore their
rush in getting more from our office!
They were sweeping up ball bearings for weeks!
Charlie
Edmondson Engineering
Unique Solutions for Unusual Problems
Chris Lewis
motor-generator set to produce 250V at 50 HZ (to test some equipment
destined for overseas). The MG was essentially a 25HP 600V 3-phase
motor driving a 250V 50Hz generator.
The panel was at 480 volts, so they ordered a 480->550V 3 phase
step-up transformer.
Electrician puts 60A fuses in the panel, pushes the button, and the fuses
pop.
Must be startup surge he thinks. So he puts in 100A fuses.
When he pushed the button, the fuses exploded. The resulting flash
melted his coffee cup about 6 feet away, and scared him out of a few
decades of growth.
The busbars arced over thru the flash, and slagged several sections
of distribution panel, blew two 2000A mains fuses, and started a fire on
the pole pig and in the vault. So much smoke that all the alarms went off,
and only a quick-thinking operator managed to stop the Halon dumping in
the computer room.
We later diagnosed it probably as a combination of poor connection in
the panel, and the transformer saturating (acting like a dead short)
trying to start up the MG.
Took almost a week to bring the building back up completely. Had to
rent the fuses until new ones could arrive.
Weeks later they tried the MG again, and it was fine.
My personal worst when I was (stupidly) routing a bare 14ga ground deep
inside a live fuse panel. The bare ground contacted both busbars behind
the fuse blocks, and vaporized under my fingertips. Leaped off the
ladder and bowled my father and grandfather over. Not even a scorch
mark to show for it.
--
Chris Lewis, 8M50-I
For more information on spam, see http://spam.abuse.net/spam
It's not just anyone who gets a Starship Cruiser class named after them.
Paul Burke
A friend was in a team commissioning a new London tube train control
system back in the 70's, the first ones to have solid- state motor
controls. They were getting problems, and fuses kept blowing- very
expensive big fuses. Someone came up with the idea of using stripboard
as a cheaper alternative, whcih worked fine as long as it was kept in a
bin full of water. They positioned an apprentice to watch the setup, and
the testing continued. The only problem was that, whenever a fuse blew,
a fountain shot up, soaking the lad. He looked round and found a lid to
cover the bin. Next time the fuse blew, the fountain shot up, so did the
lid. It came down, sideways on, and landed across the terminals on the
stripboard. Naturally, it was a metal lid. The resulting conflagration
completely destroyed the thyristor stacks, and everything else in the
vicinity.
Paul Burke
David Stephens
received a bill from a customer for a garage roof, one can of paint, and
a ball cap. Of course this had to be investigated. What we found at the
scene was a garage that was too close to the power line easement with an
unusual color scheme. It seems that the owner was painting the eves of
his garage by laying on the roof and leaning over the edge holding a can
of paint. He said he didn't notice his ball cap pushing on the secondary
wire strung between the poles and managed to push one leg into another
causing a spectacular short. His hat was damaged by the sparks thus the
ball cap part of the bill. In the excitement, he flung the can of paint
across the roof thus spilling it and ruining the roof.
David S.
hoor...@my-deja.com
I was sanding an oak floor for a friend with one of thoes huge power,
drum sanders when a fuse blew. I went down into the basement to find
the fuse box. Locating It I grabed a spare fuse and replaced the
failed one. I imediatly heard the sander start and take off across the
floor above. In a panic, instead of doing the obvious and pullling the
fuse, I ran off all the way around the house and up the front stairs.
When I finly caught up with the sander, it had run up against a wall
and was diging its way to China. Duh.
David Stephens
> The adult reader of this wants to know if the power company paid- not
> interested in the slapstick comedy. In this state, the power company has
> taken some pretty big hits on that attractive nuisance theory for minors.
> How big? Well there was a recent $28M judgment awarded for a kid that went
> under the fence of a transformer farm, and then deliberately touched an HV
> terminal on a dare. He lived but suffered massive third degree burns which
> will require a multitude of expensive skin graft operations throughout a
> substantial number of formative years. A second case involves a minor who
> drowned when he slipped into the water of a pond containing a fairly massive
> unchecked ground fault leak from a power company pump. This was deemed a
> wrongful death, and the power company shelled out the cash.
I never found out. My assumption was that they did not pay as the garage was
built overhanging the easement. I was back in school before it was resolved and
my story is over two decades old. Other incidents involve hawks capturing snakes
and flying up to the nearest wire with their prey dangling down to the next
wire. 24 kV leaves only feathers to mark the spot. On a more serious note: While
returning to the dorm from student hangouts, I passed a frat house putting up a
spectacular house decoration for homecoming. I commented to my friends at the
time that I wouldn't get near it because of the proximity of a scaffold to a
power line. This was seen as rather odd from a person who cooked hot dogs by
sticking wires in the ends and plugging them in. Shortly after both the city and
university deemed the structure safe, several students were killed and nearly
incinerated by contact with the power line. I, along with several thousand other
students, saw the students going up in sparks and flame. The line was a feeder
with large breakers so their contact did not trip the line.
I have dealt with several cases more recently as I was involved in the
manufacture and certification of a high voltage detection device to protect
outside plant workers. Part of the reason I was involved in this was because of
my experience of witnessing the school tragedy. The cases usually involved such
things as buried power cables in new subdivisions that became shallow when the
earth grade was changed. Telephone workers assumed the cables were the more
shallow telephone cables and started cutting with their handy cable sheath
knife. The worker was fine but the knife was a total loss.
One case I was asked to study and comment on involved a telephone worker killed
by AC from a telephone wire pair. During the preceding weekend, a truck had
caught and broken the neutral of a power line feeding a gravel plant. Normally
the return current would be shunted to ground but rocky soil such as this does
not conduct well and the entire facility became charged enough to arc backwards
through the lightning protectors of the telephone lines and fuse them shut. This
blew the protectors at the central office open. The neutral was promptly fixed
but voltage drop along it, without a better ground, left the facility at 180
volts. Since the lightening protectors were fused solid, this voltage became
apparent along the telephone lines away from the local ground of the facility.
The telephone worker opened a pedestal to access the lines some distance away
and had his knees on the wet grass when he stripped the small wires with his
scissors.
Another case involved a gang stealing telephone cable for copper in rural areas
by cutting it down from the poles. In one span, there was an open neutral and
return current was through the telephone cable sheath, that was until they cut
it. The two bodies, still holding the cutters, were found some time later by
repairmen.
One product I tried to get authorization to design was a current detector for
cable sheath and ground currents that become lethal voltage when opened. My
former employer didn't have the same sense of need that I did.
David S.
TinMan1332
>drum sanders when a fuse blew. I went down into the basement to find
>the fuse box. Locating It I grabed a spare fuse and replaced the
>failed one. I imediatly heard the sander start and take off across the
>floor above. In a panic, instead of doing the obvious and pullling the
>fuse, I ran off all the way around the house and up the front stairs.
>When I finly caught up with the sander, it had run up against a wall
>and was diging its way to China. Duh.
As my father would have said: "Boy, I don't think I woulda told that story
<G>."
BobH
microwave, came into contact with 13KV survived. The
stench was awful and his shoes had to be surgically
removed. Came back to carefully assigned work.
Douglas W. Jones,201H MLH,3193350740,3193382879
by "BobH" <Bob...@REMOVEemail.com>:
> A technician, who has previously burnt his cornea with
> microwave, came into contact with 13KV survived. The
> stench was awful and ...
I can attest to the stench. I've only done 5KV, and it was from a
current limited 3mA supply. The problem is, 5KV at 3mA is 15 watts,
and most of this was dissapated in two places. One was my knee,
where it rested gently against the steel frame of the lab bench, and
the other was my little finger, where it accidentally dragged over
the an exposed 5KV trace in the circuitry I was testing.
Something under 2 cubic millimeters of skin exploded, leaving a crater
at each contact point. The stench was awful, and after sensation
returned (I was stunned for a few seconds) the wounds began to hurt
like the dickens, and they took forever to heal.
That was in the spring of 1973.
Doug Jones
jo...@cs.uiowa.edu
John Woodgate
MLH,3193350740,3193382879 <jo...@cs.uiowa.edu> inimitably wrote:
>The stench was awful,
(Callous comment.) I quite like the smell of fried bacon, and I can see
why the name 'long pig' was appropriate in bygone days. (;-)
--
Regards, John Woodgate, OOO - Own Opinions Only. Phone +44 (0)1268 747839
Fax +44 (0)1268 777124. http://www.jmwa.demon.co.uk I wanted to make a fully-
automated nuclear-powered trawler,but it went into spontaneous fishing.
PLEASE do not mail copies of newsgroup posts to me.
Tom MacIntyre
I always liked that "Roast Pig" story...Charles Lamb?
Tom
Terry Sanford
> .... we found at the scene was a garage that was too close to the power
> line easement ....
How come it got built there in the first place? Maybe it should be moved?
Dangerous too!
But seems to happen all over!
In many neighbourhoods people prefer either underground services or for pole
lines to be to the rear of their lots
Frequently and particularly when services are provided from the rear of the
properties, many homeowners don't seem to realize that there are easements
and right of ways either on 'their' property or adjacent to it, on which
they must not, but do, build fences, sheds, sand boxes, play equipment etc.
Then when there is a major power outage or storm or other emergency, the
various line crews have a devil of a time trying to get in to repair the
services.
Heard of one instance where a utility company was, during an emergency,
authorized to put a bull dozer down the back of some properties to clear
away all kinds of construction, by successive homeowners within the
easement/right of way. Was the only way to get in and replace snapped off
poles and restore power to a large residential area! The poles were for a
fairly high voltage line, were large and too heavy to carry in, manually
from the street through peoples front and back gardens, along with
attachments and fittings for each new pole.
Some people had even attached fences to the wooden utility poles! In others
there was not even the mandatory minimum clearance to allow a firemen to get
in with a fire hose.
Urge all homeowners to read and be familiar with the deeds, purchase
agreements or land grants entered into by the 'ORIGINAL' owners of your land
or dwelling, particularly in regard to any rights of way or easements. Also
to be familiar with any other 'permissions' that have been given by or which
limit the previous owners.
We had a case recently where the driveway of number 21 had to be torn up in
order to fix the water supply valve for number 23. The present (fourth)
owner of number 21 had no knowledge of the presence of the water valve!
Fortunately, in this case, goodwill and good sense co-operated and there
was no delay.
Just a comment.
PaulMmn
bank of a local creek. I was moving carefully along the bank, and
slipped. I reached out and grabbed the nearby fence for support.
It was an electric fence (designed to keep the cows in). I couldn't
move as all that electricity zapped from the fence, through me, to
ground.
Fortunately, these fences are pulsed (ie 2-3 second cycle square
wave), or I'd -still- be hanging on!
--Paul E Musselman
Pau...@ix.netcom.nospam.com
On Fri, 01 Dec 2000 01:39:02 -0500, Tony Miklos
<tmi...@netcarrier.com> wrote:
>That reminds me of the time I was standing in a creek (a teenager). A
>thunderstorm came up real quick. We were at a slippery part of the
>creek. The bottom was mostly clay. So while grabbing onto a fence,
>pulling ourselves out of the creek, the lighting hit the fence. Luckily
>it hit a half mile away. We did feel one hell of a zap though! No,
>there was no sine wave;-) Only two kids running as fast as they could
>for home!
PaulMmn
had its own local breaker panel, and we wanted to add an additional
outlet. Having no access to the upstream panel, we (engineering
students all) took the cover off of our panel, and looked carefully at
the situation. We all agreed that it would be simple to guide the
wire -there-, and tighten -that- screw.
I was carefully working and had just started to tighten the screw,
when a friend walked in and asked what I was up to. I turned my head,
and avoided seeing the sparks! My screwdriver had an 1/8" notch
burned in it; my glasses had metal flecks embedded in the lenses.
Thank heavens for astigmatism!
I quickly wrapped the screwdriver in question with electrical tape,
and successfully (albeit stupidly) continued with the installation.
And my screwdrivers -still- have electrical tape on the shafts!
--Paul E Musselman
Pau...@ix.netcom.nospam.com
On 4 Dec 2000 22:54:50 GMT, cle...@nortelnetworks.com (Chris Lewis)
wrote (in part):
PaulMmn
find the charge of the electron (!). It involved 2 metal plates about
a quarter inch apart. You use a telescope to peer between the plates,
spray some oil into the gap, and use 500v DC (reversable) between the
plates to make a droplet of oil rise and fall. Timing the movement
was supposed to figure out the charge of an electron.
Well, all was going well, the droplet was moving up and down, and a
friend (yet another one) asked about the setup. I was happy to show
off, and pointed at the metal plates and explained the 500v DC. Then
I explained the neat hole drilled through my fingertip!
--Paul E Musselman
Pau...@ix.netcom.nospam.com
On 8 Dec 2000 15:31:38 GMT, jo...@cs.uiowa.edu (Douglas W. Jones,201H
Gordon Reeder
the armed services. He was doing KP duty directly
after breakfast. All of the sudden the Coffee pot
starts sparking and smoking. This is no ordinary
coffee pot. It could brew 8 pots simultaniously.
So they called in an electrician who took a look
at the sub panal, cursed loudly, and took off at
a dead run. This is not good. He came back with
his supervising officer who had a simular reaction.
It turns out that somone had wired up the coffee
pot directly to the input bus of the panal. THere
was no breaker to turn the pot off. In order to
disconnect the coffee maker they had to secure
opperations on 1/3 of the carrier and the flight
deck.
Pau...@ix.netcom.nospam.com (PaulMmn) wrote in
<5tab3t0h79h45haq4...@4ax.com>:
>I've only done 500v DC... It was in a physics lab. We were trying to
>find the charge of the electron (!). It involved 2 metal plates about
>a quarter inch apart. You use a telescope to peer between the plates,
>spray some oil into the gap, and use 500v DC (reversable) between the
>plates to make a droplet of oil rise and fall. Timing the movement
>was supposed to figure out the charge of an electron.
>
>Well, all was going well, the droplet was moving up and down, and a
>friend (yet another one) asked about the setup. I was happy to show
>off, and pointed at the metal plates and explained the 500v DC. Then
>I explained the neat hole drilled through my fingertip!
>
>--Paul E Musselman
>Pau...@ix.netcom.nospam.com
>
>
>
>
--
Just my $0.02 worth. Hope it helps
Gordon Reeder
greeder
at: myself.com
Terry Kennedy
> It was an electric fence (designed to keep the cows in). I couldn't
> move as all that electricity zapped from the fence, through me, to
> ground.
I wonder if the cows notice it much... Years ago, I put up a community
antenna TV system (yes, the original CATV acronym) way out in the boonies.
We negotiated with a farmer for the use of a 10 x 10 plot in the middle of
one of his pastures, and put up a 150' mast and antenna. The guy wires were
anchored into concrete pads in concentric squares outside the fenced-in 10x
10 plot. We had a tube-based headend preamp we scrounged from a "real" cable
system, which consisted of a small module at the top of the mast and the meat
of the amp in a shed at the base.
We got reports of fade and heavy static every evening around dusk. Putting
a scope on the base showed the signal was indeed fading from the antenna and
preamp up at the top of the mast. So I climbed up the mast (yep, all 150' -
I was a bit crazy in those days) and just as I got to the top, the mast began
*swaying* like mad!
The explanation was that the farmer was moving the cows into this field at
dusk, and they liked to rub against the guy wires, causing the antenna to
sway and move off-axis.
We had to negotiate with the farmer to be able put up additional fenced-
in areas around the guy wire anchor points.
Terry Kennedy http://www.tmk.com
te...@tmk.com Jersey City, NJ USA
Richard Bell
Terry Kennedy <te...@gate.tmk.com> wrote:
>In alt.home.repair PaulMmn <Pau...@ix.netcom.nospam.com> wrote:
>> It was an electric fence (designed to keep the cows in). I couldn't
>> move as all that electricity zapped from the fence, through me, to
>> ground.
>
> I wonder if the cows notice it much...
Cows are actually quite sensitive to electicity (They are amazingly well
grounded) and a depressingly small current (still much larger than the fence
puts out) will kill them. Once a cow has learned that bruching against the
fence shocks them, the only reason that the farmer needs to keep the current
flowing is that cows are mean, and high status ones will occassionally force
low status ones into the fence (they are also stupid and may not notice the
fence in time to avoid it). A stray ground current that elevates the water to
3 volts will prevent them from aproachng it.
Rich Grise
lame, though. At the age of about 4 I got missed by a lightning
stroke, and since it was 45 years ago there's nobody still alive
who can corroborate it. That same year or so, I learned to keep
my thumb out from between the prongs when plugging in a lamp.
At the age of about 12 or so, I was playing with a train
transformer and car coil, burning nifty patterns in a piece of
wood. Got across the (estimated) 1900 volts. Zap! It was
actually kind of fun. During that same time frame, (the late
50's, early 60's), there was a thing at the penny arcade where
you could put in your nickel or whatever, and it had two
chrome knobs that you held in your hands. One of them would
rotate, and there was some kind of indicator, and the farther
you rotated it, the more intense of a shock you got. I think
I won. That's probably why I'm so brain damaged today.
Actually, I can think of a couple of occasions where we did
that sort of thing to each other, but I'm not proud of them.
Cheers!
Rich
kblac...@hotmail.com
John Popelish <jpop...@rica.net> wrote:
> Bill wrote:
> >
> > This is a little thing that caused thousands of dollars worth of
damage to
> > several large (mini) computer systems.... A company I worked for
decided to
> > open up the computer installation field to females. >
> Bill, you sound like you are enjoying the memory of this event just
> because it happened to be a female who made this boo boo. You sort of
> imply that men have never made stupid mistakes like this.
>
> John Popelish
>
John, I was gonna say!
Bill, lots of people trying to prove themselves make mistakes like
this. I hope your first wife still loves you ;->
David Combs
I was part of the "support" for a play being put on.
We had to dim the lights, somehow.
No dimmer.
So the counselor working with us got me a
large tin-can from the kitchen.
Attached a stick to the top (now separated)
and filled the can with mixture of water and
copper-sulfate.
One side of circuit to bottom of can (via insulated
wire going down in water to bottom, maybe to 2nd "top"
resting at bottom?), other side to
top, and I would raise and lower the (wooden!) stick
and top into the mixture.
And lived to tell the story, since, amazingly,
nothing went awry.
David
PS: Sorry if this story disturbs your sleep while
YOUR kids are off at summer camp!
Dave Balderstone
Pau...@ix.netcom.nospam.com wrote:
> A similar event happened to me: I was fishing with a friend along the
> bank of a local creek. I was moving carefully along the bank, and
> slipped. I reached out and grabbed the nearby fence for support.
>
> It was an electric fence (designed to keep the cows in). I couldn't
> move as all that electricity zapped from the fence, through me, to
> ground.
>
> Fortunately, these fences are pulsed (ie 2-3 second cycle square
> wave), or I'd -still- be hanging on!
Here's an absolutely true electric fence story.
When I was in my early 20's we had a small hobby farm. We decided to buy
6 weaner piglets and raise them for meat. The advice we had was to use
an electric fence, so we bought the charger unit, and a bunch of wire,
posts and insulators, and set up a nice pen in a muddy, but densely
overgrown pasture that had been laying fallow for a couple of years.
Perfect for pigs.
My brother Brian and I built a crate in the back of his pick-me-up truck
(brother Sean had wrecked his leg in a motorcycle accident, brother Gord
is disabled, sister Suzanne was only about 5, and we didn't like to let
our mom near tools <g>), and headed for the Cloverdale auction, where we
managed to get a half dozen little porkers at a good price. Then it was
back to the farm, and with little ado we managed to get them into the
pen.
Now, pigs are very intelligent animals, and the little piglets quickly
learned to stay away from the fence. This particular fence sent a pulse
of electricity through the wires every 1.5 seconds, not enough to
injure, but a good jolt for a little piggy standing on the wet ground of
British Columbia's Fraser Valley.
Pigs are *so* intelligent, in fact, that we soon realized we could save
power by turning the fence *off* after they had learned that if they
touched it, they got zapped. Only thing is...
Pigs are *so* intelligent, in fact, that we soon realized we had to make
sure we turned the fence *on* again every few days, because if one of
them accidentally touched it and *didn't* get a zap, the fact was
quickly communicated to it's piggy siblings.
Of course, one day, we left it a day too long and *all* the pigs escaped.
It was a sunny morning, and I was hoeing the corn, dressed only in a
pair of gumboots and a pair of cutoffs, with my (then) long hair tied
back in a ponytail, when I heard a yell from Brian, "Oh SHIT! The pigs
are out!" I dashed out of the corn, and jumped the wooden fence into the
pasture. Brian yelled for Mom to turn the electric fence back on, and
the chase was on, Brian and I in the wet pasture, and Mom, Sean, Gord
and Suzanne leaning on the fence and watching in a mix of concern and
amusement.
Brian and I quickly developed a strategy of picking a single piglet,
herding it toward the pen, and then leaping at it, grabbing the back
legs, and quickly lifting and depositing it back inside the pen, where
it quickly learned that the power was back on.
We were down to two pigs left, and I was hot on the trail of mine. I saw
Brian catch his last one, flip it gently into the pen, and then turn to
try to head mine off.
The pig and I were racing down the long side of the pen, and I was
preparing for my leap. By this time I was covered in wet mud, and
sweating rather profusely. As we near the end of the pen, the pig made a
quick turn, right at the corner, along the short side.
I tried to do the same.
I failed.
My feet went out from under me and I landed on my side, in the mud, with
three wires under me. One just above my hip, one at the bottom of my rib
cage, and one under my arm.
Now, recall two things:
1- The fence was set to deliver a pulse of electricity every 1.5 seconds.
2- The fence was now turned on.
Time slowed to a near standstill as I realized that:
1- The fence was now turned on;
2- I had less than 1.5 seconds to get to my feet; and,
3- There was no way in hell I was going to make it.
ZAP!
While I suffered no injury, except to my pride (I was the only one
present who *wasn't howling with laughter), I discovered just how
effective a farm electric fence can be in aiding a young man to his
feet, quickly. When the jolt hit me, I was propelled nearly upright, and
then fell backwards, to land in a sitting position in the mud.
Fortunately, Brian had indeed managed to catch the last of the piglets,
and that part of the ordeal was over except for the laughter from my
family, which continues to this day.
Later that year, the pork was somehow even tastier than I had imagined.
--
Remove *** from email address to reply
Greg Beaulieu
Mine is pretty tame by comparison, but it did amaze me. New Year's Eve
about 5-6 years ago. I was girlfriend-free at the time and so was at home,
alone, around midnight. Had a pretty good time actually -- ordered in some
take-out, had watched a couple of movies and had a few drinks, and was
preparing to watch Dick Clark on ABC. I was living in an apartment on the
21st floor with a spectacular view of downtown and points beyond.
Sitting on the sofa I see bright flashes of light thru the windows.
Fireworks, I assume. I look out to see no fireworks, but huge arcs
originating in the power company transformer farm down on the waterfront
about a half-mile away. It looked like an old Boris Karloff movie. I kept
waiting for my lights to go out, but they didn't even flicker. The arcs
kept up for 5-10 minutes, and I'm thinking that *someone* at the power
company must know about this, and that they'll throw the switches soon
enough. But they keep going, and going, and I see that sections of town
beyond the transformers are now in darkness. You can see whole city blocks
go out in sequence when you're up that high -- very cool. I watched as
portion after portion of the city grid tripped out.
Finally I realized that maybe the power company really didn't know about
it. Maybe everyone was off for New Year's. I called, and eventually got
thru to a lady who must have been one of a handful of people actually
working there that night. I told her what I was watching thru the window.
I couldn't believe her response: "Oh, so *that's* where it's coming from!
Thanks!!!".
A few minutes later the arcing stopped. Dunno how long it took them to put
the power back on. Mine stayed on OK, I watched the ball fall in Times
Square, and went to bed. :)
--
Greg Beaulieu ab...@chebucto.ns.ca Dartmouth, Nova Scotia, Canada
My Homepage: http://sites.netscape.net/ab348/homepage
Dave
http://www.drmegavolt.com
Bob
out what an electric fence would do, so he caught a convenient kitty, and
holding it, touched the kitty's nose to the fence. He said the next thing he
knew, he was 8 feet back on the ground.
Bob
Aki
swung a leg over their bike, fired it to life, looked at me and
belched:
...hmmm...sounds like he may have exaggerated a little. My
grandparents had a farm in Nebraska that I used to spend the summers
on and they and the surrounding farmers also had electric fences.
The "shock" of one of those fences, although very uncomfortable,
wasn't anything that would blow someone back 8 feet. However, if what
you friend is talking about is a SECURITY electric fence, that might
be another story!
cheers,
-aki
01 FXDWG
85 700 Magna
AMA Lifemember...
DoD#0628...
HOG,MANS,
yada,yada
Philip Lewis
That reminds me of a story told to me by one of my good friends Eoghan
Macdubhshithe. (MacFee)
In his youth, he lived on a farm near Wheeling WV. They had pigs.
Now some people don't realize just how mean some pigs can be. they
*are* extremely intelligent and have varying personalities. Now there
was this one pig who was a biter. It particularly liked to bite my
friend.
On occasion it became necessary to enter the pen with this
particular animal, and so out of self defense, my friend made a
portable electric fence. it was an insulated poll with a wire which
was attached to the fence. he'd grab the poll and herd the pigs to
move them about as needed.
one day the mean one snuck up and got a nip in, which didn't please my
friend none too much. Eoghan took his poll and zapped the pig a few
times. The pig didn't turn away, but was gradually backed into the
opposite side of the pen, where there was in fact more electric fence.
Did i mention this was a male pig, and that he was backing up?
A particularly sensitive part of this pigs anatomy came into contact
with the fence first. The pig started and took off in a run towards
the other side of the pen. Now I've never known pigs to be
particularly good jumpers, but when he reached the other side with the
momentum granted to him by such a tender encounter, he jumped and
actually cleared the fence and kept running until he disappeared into
the woods.
After my friend got over his amusement he realized that he now had to
go and fetch the pig, which he did.... (not that Eoghan minded
tromping about in the woods, but the thought that he *had* to go and
find the pig took the enjoyment from the task)
In the weeks that followed, the pig managed to dissappear from the pen
a little more often than was usual. Eoghan was stuck with the task of
finding him each time. They couldn't figure out how the pig was
getting out. it never did anything when people were around.. Remember
when i mentioned that pigs are smart? Well, Eoghan, being just
slightly smarter than the pig and motivated by not wanting to go and
chase the bugger again, decided he'd figure how the pig escaped. He
(Eoghan, not the pig) sat on a barn roof a good ways away from the pen.
Not much happened for several hours but eventually the pig seemed to
look around, then slowly start backing up. He approached the wire,
and ZAP! off he went across the pen running at full charge (no pun
intended) and jumped over the other side.
REVELATION! Eoghan realized that he taught a pig to fly. Knowing now
that the effort of fetching the pig was going to be futile, Eoghan
"didn't find the pig" this time... um ... there must have been a
"hunting accident" of some sort.
TimothyBil
Back in the olden days when I was growing up, a test of manhood was to p*ss on
the wire. The only problem was that that was when the transition was being
made from the old electromechanical units to the totally electronic ones that
put out a much hotter spark! The older guys had succusfullly passed the test
on the old systems, and were now egging the younger guys on, usually on fences
that had the new systems but they didn't know that. A couple of guys with burn
marks at the end of their you-know-wheres pretty much put a stop to that
particular manhood test. :-)
Chris Lewis
> Sitting on the sofa I see bright flashes of light thru the windows.
Speaking of which...
When the ice storm of '98 hit, the ice loading bent and broke off power
poles, transmission lines and large steel towers. At times made you
think of a war zone - trees/branches snapping off almost like machine
gun fire, and you could see huge flashes lighting up half the sky as
lines sagged and went down. Even tho normal visibility was only a hundred
yards or so, we saw these flashes from 4 or more miles away.
Flashes appeared to be rapidly expanding and contracting domes of intense
white (or sometimes blue) light - you didn't see the arc itself because
all the moisture in the air diffused it.
Just like footage of A-bomb ground tests. Without the mushroom cloud.
We were lucky. Our power was only out for 36 hours. Some people were
over a month.
--
Chris Lewis,
For more information on spam, see http://spam.abuse.net/spam
It's not just anyone who gets a Starship Cruiser class named after them.
David Combs
David Combs <dkc...@panix.com> wrote:
>Aeons ago, when I was in summer camp as a kid,
>I was part of the "support" for a play being put on.
>
Actually, as I now recall, it was a glass wide-top
bottle, with one can-lid (wired) at the bottom,
and the other at the end of the stick.
The can was only the source of the top and
bottom pieces, each attached to one side
of the 110.
David
John Miles
>
> <snip>
Fascinating stuff. I knew there was a reason I saved this thread to
read on Friday....
-- jm
------------------------------------------------------
http://www.qsl.net/ke5fx
Note: My E-mail address has been altered to avoid spam
------------------------------------------------------
Turnkey
Reminds me of the the first huge blackout in the Northeast in the
60's. I was fixing dinner in my dorm at Syracuse U. That was on a hill
high over the city. Dark out and I'm leaning on the railing waiting
for water to boil when, with no warning, the entire city disappeared.
Only light visible was some sort of plant about 15 miles away with
their own power. It was just a great big black hole.
Harry K
Rich Grise
>
> Here's a guy that make a living toying with huge tesla coils.
> http://www.drmegavolt.com
Interestingly, I've seen that sequence of the guy getting zapped
on the power pole, and they said he lived.
Incidentally, I've heard on the local news that the reporter
who got zapped so badly a few months ago when they raised the
antenna into a 2300V line has gone home, and will be basically
OK. Well, at least, she's still alive. Got a couple of fingers
missing, but apparently she can still talk and stuff.
Be Safe!
Rich
Dave
ron butchart
been available that would have prevented the accident!!
"Rich Grise" <rich...@vel.net> wrote in message
news:3A3C54...@vel.net...
Germanating Thought
The electric company who advertises constantly that you "should leave power
lines alone"?
The TV Station for not advising her of the dangers of antennas?
Herself, for excessive stupidity! She might be able to win millions from
herself.
:->
I once tried to fix an electric hot water heater. After each attempt I would
wait awhile and see if the water was getting warmer, getting my hands wet in
the process. I was using a Swiss army knife to adjust the electrical leads.
Even though I had been trained repeatedly on the importance of
Tagout/Lockouts when dealing with electrical equipment. I discovered that
220 is very exciting with wet hands and swiss army knife. I didn't find the
swiss army knife for a while. I don't mess with energized electrical
equipment anymore. (I only suffered from the humbling nature of my
stupidity)
ron butchart
Reporter Sues Companies Over Accident in News Van
By LOUIS SAHAGUN, Times Staff Writer
The accident that critically injured KABC-TV reporter Adrienne Alpert
could have been avoided if the microwave transmission gear her crew was
using had standard safety devices, according to a lawsuit filed Wednesday in
Los Angeles Superior Court.
The suit charges several manufacturers of the equipment with failure to
use technology designed to prevent roof-mounted masts from hitting power
lines, Alpert lawyer Bruce Broillet said in a statement.
On May 22, a station photographer accidentally raised her broadcast
van's 42-foot microwave mast into a 19,900-volt line in Hollywood, burning
Alpert, who was in the vehicle. A power surge of 34,500 volts shot through
the van and Alpert's body.
The reporter has undergone amputation of her lower right leg, left
forearm, part of her left foot and several fingers on her right hand.
KABC-TV Channel 7 officials were unavailable for comment.
Broillet said, "This equipment involves highly sophisticated microwave
technology, yet its safety equipment is so archaic it might as well have
come over on the Mayflower."
In October, state officials cited KABC-TV for safety violations that
could cost the station close to $30,000 in fines for the accident.
Since 1985 at least 20 injuries or deaths have been reported nationwide
in connection with similar television microwave-electrical power line
accidents, Broillet said.
In the meantime, he said, "Adrienne is focusing on her recovery, but
she is gravely concerned about her colleagues. She hopes [that] by holding
manufacturers accountable to a high standard of responsibility, the entire
news reporting profession will benefit."
Copyright 2000 Los Angeles Times
"Germanating Thought" <the...@tznet.com> wrote in message
news:B6625D6A.3338%the...@tznet.com...
Bruce Potter
Excuse me, but just what <Technology> can stop 19,900 volts at many
kiloamps from travelling to ground through a metal antenna with metal
wires running all the way down the pole, with a steel-bodied vehicle
attatched to it?
If you're going to raise your antenna MAKE SURE YOU"RE NOT
PARKED UNDER ANY POWER LINES for christs sake!
These things raise straight up, it's not that hard to look out the window
and see!
She doesn't get any sympathy from me.
If she's going to sue anyone, she should sue the photographer who
<accidentally> raised the thing in the first place.
Just my opinion, and I base it only on the facts presented in the previous
article (so it probably doesn't mean much!)
Bruce
Tom MacIntyre
wrote:
If it was not her own misdeed that caused her injuries, she gets
sympathy from me.
Tom
Germanating Thought
must be someone else's fault. I am all for improving the safety of devices,
but it doesn't solve the more basic problem of human arrogance. We don't
like to think that it might be our fault that we were injured.
Technology can help, but the operator has to be the one who ultimately
responsible for the use of a product. I don't know if the instruction for
the microwave antenna clearly indicted the need to clear the overhead before
raising, but all the devices I have seen that can extend into a power line,
have had warnings.
One of the dangers of technology is the dumbing down of the operator. This
accident was the fault of the photographer who raised the antenna. Every
news agency in the world should be having a safety session with their
employees regarding raising conductors into power lines, or overpasses, or
covered garages.
Please add any other location where it might be dangerous to extend a
mechanical boom.
When a person drops a cinder block on the bare foot, I don't go out and
create a new technology to protect the bare foot, I tell the employee to
where the appropriate foot attire.
The manufacturer may have some liability. The real liability is with the
news agency. They obviously had not stressed safety enough. If that is not
true, then the photographer should be looking for another job.
Tony Miklos
>
> Once again we fail to realize that we are responsible for our actions. It
> must be someone else's fault. I am all for improving the safety of devices,
> but it doesn't solve the more basic problem of human arrogance. We don't
> like to think that it might be our fault that we were injured.
That made me think of a quote of Thomas Edison's in this months Popular
Science "75 years ago" section. When they asked him what inventions the
world needs most? He replied "We don't need more inventions until
intelligence has increased so we can operate what we have."
--
Tony
Steve
Actually she lost a leg, an arm, fingers on her remaining hand, and had
burns all over. That's NOT "Ok".
-Steve
--
-Steve Walz rst...@armory.com ftp://ftp.armory.com/pub/user/rstevew
-Electronics Site!! 1000 Files/50 Dirs!! http://www.armory.com/~rstevew
Europe Naples, Italy: ftp://ftp.unina.it/pub/electronics/ftp.armory.com
Richard Bell
ron butchart <no_one...@hotmail.com> wrote:
>She is, however, suing someone on the grounds that "technology" should have
>been available that would have prevented the accident!!
>
to excercise the due caution of looking for wires. If she raised it herself,
and failed to look for power lines, she has unfortunately gotten what she
deserved; unless, she was given the equipment without proper trainging. You
can bet the farm that the owners' manual for the deploying mast has, in BIG
BOLD LETTERS, do not raise the antenna near power lines, as a complement to
all of the bright yellow stickers emblazoned with the same warning scattered
liberally ove the entire truck. So, if everyone has excersised due care,
except the individual that raised the antenna, who ever she sues probably does
not have a lot of money.
While the technology does exist to warn the drivers of construction equipment
about approaching power lines, there may be some difficulties of providing
the same equipment to antennas (which are high voltage sources, themselves).
Spehro Pefhany
>>
> She can only sue the person that raised the antenna, as that individual failed
> to excercise the due caution of looking for wires.
Nonsense. She can sue anyone she pleases, if there is no reasonable
connection with the incident it should be thrown out fairly quickly.
Examples: The equipment manufacturer (why wasn't it insulated? were there
no warning labels? ), the employer (why didn't they train the operator
properly?, why were they too cheap to have a second operator on there to
be sure the first one didn't screw up) , the power company (why didn't
they have a fence around the wire or insulation on it or warnings on the
wires themselves). In practice, anyone with deep pockets and some
connection with the incident can expect to be included.
Best regards,
--
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Spehro Pefhany --"it's the network..." "The Journey is the reward"
sp...@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
Contributions invited->The AVR-gcc FAQ is at: http://www.BlueCollarLinux.com
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
dod...@my-deja.com
(pre-Christmas silence it seems).
My own stories, like others, are tame compared to stories of vaporising
bus bars, exploding breakers etc. but I thought I'd post them anyway.
I used to do the occasional bit of gardening for neighbours to earn
some money when I was at university. One of these neighbours asked me
to trim their hedge with pair of garden shears (the ones like big
scissors, not electric ones). I was quite happily hacking away at this
hedge when something distracted me, but I continued cutting whilst
looking elsewhere. My attention was rapidly refocussed by a loud bang
and a blue flash from the hedge. The house owners had run the
unprotected power cable for their greenhouse through the hedge, about
four feet from the ground! Just the right height for the, thankfully,
rubber handled shears to cut through.
I'm lucky to have made it into my teens, let alone my thirties, as I
seemed to have had a fascination for connecting myself to live
circuits. Not only have I done the common (well it seems so from this
thread) kid's trick of putting my fingers on the pins of a partially
inserted plug, but I did once try to heat up a darning needle by trying
to hold it against the element of an electric toaster. Neither the
needle or the toaster survived that, but I did.
Have fun!
Graeme