Electrical Engineering - Playing with electricity :)

Author

Playing with electricity :)

Mark Conrad

2007-02-11, 5:25 pm

In my 2nd childhood now. This here lec-ertricity is the greatest thing
since sliced bread to jump-start my ailing 78-year old ticker.

Have one foot in the grave and the other foot on a slippery banana peel.

Heck, just to get going every morning I have to fall down a couple of
times, to get my juices flowing in the right direction.

Now don't lecture me about safety, I am entitled to play after a
lifetime of work.

Besides, I live in a rural location where if my house burns down it
would actually be a service to other residents, because this 50 year old
house of mine is an eyesore.

Only thing still holding my house together is the fact that all my
termites are holding hands.

My house wiring is totally shot, various arcing noises and the smell of
ozone coming from behind my walls.

Has a benefit though, all the mice keep getting electrocuted from the
bare wires, installed by my house builder because he was too cheap to
use conduits.

Back to playing with electricity -

DISCLAIMER - DO NOT try to do this yourself, any one of a number of
things could go wrong and you would wind up dead. I know what I am
doing, having worked around high voltages for 34 years

The agenda yesterday called for charging up my small compact car to
10,000 volts, as measured by my DC field-effect voltmeter. Got the car
to 11,000 volts, then let it bleed down to 10-kv for the "test".

Those field-effect voltmeters are fairly accurate, once you learn how to
use them. For example, I can measure the voltage of a 9 volt battery
plus or minus one volt, even though the voltmeter is designed for
measuring voltages up to 20,000vdc.

It is very tough to measure the voltage on small items. About a week
ago I charged up a small stainless steel pot to 9 vdc, then removed the
charging circuit.

My field effect voltmeter accurately measured that charge. The voltage
was not affected by the voltmeter, staying at a constant 9 volts,
despite repeated measurements.

Over time, of course, the charge on the pot slowly gets destroyed by
stray ions in the air. After about a half hour there was not much of
the original 9 volt charge still left on the pot.

Back to the fun 10,000 volt "test" -

Stood with my right foot in soggy ground, then took the full blast of
the 10,000 volts by grabbing the car door handle with my left hand.

WOW, that will curl your hair, Whatta jolt! Whee!

Lemme see, figure my body resistance was about 5,000 ohms from bare
right foot to clammy left hand.

What was the approximate current through my body -

10,000 volts, divided by 5,000 ohms = 2 amps.

That means I probably had about 2 amps going through my chest area for a
brief instant.

I figure the RC time constant was approx' two-and-a-half micro-seconds
to reach the 63% point of where the voltage drops down to 3,680 volts.

(estimating that the car's capacitance to earth ground was somewhere
around 500 pico-farads... I did not have the motivation to accurately
measure it)

Mark-

Rheilly Phoull

2007-02-11, 8:25 pm

MassiveProng

2007-02-11, 8:25 pm

On Sun, 11 Feb 2007 20:37:40 GMT, Mark Conrad
<noneof@urbusiness.invalid> Gave us:

>
>In my 2nd childhood now. This here lec-ertricity is the greatest thing
>since sliced bread to jump-start my ailing 78-year old ticker.
>
>Have one foot in the grave and the other foot on a slippery banana peel.
>
>Heck, just to get going every morning I have to fall down a couple of
>times, to get my juices flowing in the right direction.
>
>Now don't lecture me about safety, I am entitled to play after a
>lifetime of work.
>
>Besides, I live in a rural location where if my house burns down it
>would actually be a service to other residents, because this 50 year old
>house of mine is an eyesore.
>
>Only thing still holding my house together is the fact that all my
>termites are holding hands.
>
>My house wiring is totally shot, various arcing noises and the smell of
>ozone coming from behind my walls.
>
>Has a benefit though, all the mice keep getting electrocuted from the
>bare wires, installed by my house builder because he was too cheap to
>use conduits.
>
>
>
>Back to playing with electricity -
>
>DISCLAIMER - DO NOT try to do this yourself, any one of a number of
>things could go wrong and you would wind up dead. I know what I am
>doing, having worked around high voltages for 34 years
>
>The agenda yesterday called for charging up my small compact car to
>10,000 volts, as measured by my DC field-effect voltmeter. Got the car
>to 11,000 volts, then let it bleed down to 10-kv for the "test".
>
>Those field-effect voltmeters are fairly accurate, once you learn how to
>use them. For example, I can measure the voltage of a 9 volt battery
>plus or minus one volt, even though the voltmeter is designed for
>measuring voltages up to 20,000vdc.
>
>It is very tough to measure the voltage on small items. About a week
>ago I charged up a small stainless steel pot to 9 vdc, then removed the
>charging circuit.
>
>My field effect voltmeter accurately measured that charge. The voltage
>was not affected by the voltmeter, staying at a constant 9 volts,
>despite repeated measurements.
>
>Over time, of course, the charge on the pot slowly gets destroyed by
>stray ions in the air. After about a half hour there was not much of
>the original 9 volt charge still left on the pot.
>
>
>
>
>Back to the fun 10,000 volt "test" -
>
>Stood with my right foot in soggy ground, then took the full blast of
>the 10,000 volts by grabbing the car door handle with my left hand.
>
>WOW, that will curl your hair, Whatta jolt! Whee!
>
>Lemme see, figure my body resistance was about 5,000 ohms from bare
>right foot to clammy left hand.
>
>
>What was the approximate current through my body -
>
>10,000 volts, divided by 5,000 ohms = 2 amps.
>
>That means I probably had about 2 amps going through my chest area for a
>brief instant.
>
>I figure the RC time constant was approx' two-and-a-half micro-seconds
>to reach the 63% point of where the voltage drops down to 3,680 volts.
>
>(estimating that the car's capacitance to earth ground was somewhere
>around 500 pico-farads... I did not have the motivation to accurately
>measure it)
>
>Mark-

This post made my week. I love ungrounded charged elements! :-]

Mark Conrad

2007-02-12, 3:25 am

In article
<45cfb732$0$31839$5a62ac22@per-qv1-newsreader-01.iinet.net.au>,
"Rheilly Phoull" <rheilly@bigpong.com.au> wrote:

> Thanks for your efforts in cleaning up the gene pool :-)

Yep, the youngsters at my old salt mine feel especially grateful for my
present efforts to clean up the gene pool.

They got tired of hearing me preach about electrical safety, because
they already _know_ everything. ;-)

One youngster there very nearly became electrocuted when he failed to
discharge a forty pound power supply for the F14 aircraft, before he
attempted to carry it off.

That unit has filter capacitors which hold a very substantial 15,000
volt charge, more than enough to electrocute a careless technician.

He was very lucky, just got knocked on his keester with a very dazed
look on his face.

Mark-

--
....present member of EEEI, ACM, AAAI

Mark Conrad

2007-02-12, 3:25 am

In article <0khvs2tv3v0fj9rn67e1ufopkgh8q19el6@4ax.com>,
MassiveProng <MassiveProng@thebarattheendoftheuniverse.org> wrote:

> This post made my weak. I love ungrounded charged elements! :-]

Yes, I got the idea last month, which was very dry weather here in
northern California.

I got tired of getting zapped every time I stepped out of my car and
grabbed the door of the car to help myself exit the car.

Especially noticeable at night, when I could see the spark jumping from
my hand to the car.

Not being totally insane, I drove my small car up onto four of those
hard plastic stands to decrease its capacitance to earth ground, in
order to further minimize the "punch" when I contacted the charged-up
car during my "test".

I imagine a large low-slung car would give the driver a fairly big jolt
in dry weather.

Mark-

Mark Conrad

2007-02-12, 3:25 am

In article <noneof-14C728.21494411022007@news.west.earthlink.net>,
Mark Conrad <noneof@urbusiness.invalid> wrote:

> ...present member of EEEI, ACM, AAAI

Good Grief, embarrassing typo there, that should be IEEE

(for: Institute of Electrical and Electronics Engineers)

Worst part is, I make that same typo often, lately.

Mark-

MassiveProng

2007-02-12, 3:25 am

On Mon, 12 Feb 2007 05:48:32 GMT, Mark Conrad
<noneof@urbusiness.invalid> Gave us:

>In article <0khvs2tv3v0fj9rn67e1ufopkgh8q19el6@4ax.com>,
> MassiveProng <MassiveProng@thebarattheendoftheuniverse.org> wrote:
>
>
>Yes, I got the idea last month, which was very dry weather here in
>northern California.
>
>I got tired of getting zapped every time I stepped out of my car and
>grabbed the door of the car to help myself exit the car.
>
>Especially noticeable at night, when I could see the spark jumping from
>my hand to the car.
>
>
>
>Not being totally insane, I drove my small car up onto four of those
>hard plastic stands to decrease its capacitance to earth ground, in
>order to further minimize the "punch" when I contacted the charged-up
>car during my "test".
>
>
>I imagine a large low-slung car would give the driver a fairly big jolt
>in dry weather.
>

Drive it up onto a nice flat sheet of aluminum!

I noticed that baggies have more static accumulation faster when
they are new, as opposed to wrinkled (delibrately).

I think the flat surface let's the electrons lattice up or such. :-]

Anyway...

MassiveProng

2007-02-12, 3:25 am

On Mon, 12 Feb 2007 06:09:59 GMT, Mark Conrad
<noneof@urbusiness.invalid> Gave us:

>In article <noneof-14C728.21494411022007@news.west.earthlink.net>,
> Mark Conrad <noneof@urbusiness.invalid> wrote:
>
>
>Good Grief, embarrassing typo there, that should be IEEE
>
>(for: Institute of Electrical and Electronics Engineers)
>
>Worst part is, I make that same typo often, lately.
>
>Mark-

Hmmm... I wonder what we could come up with for EEEI.

I have fits of "mild dyslexia", as I call it in my old age as well.

Mark Conrad

2007-02-12, 5:25 pm

In article <ui10t2563b8vnsk92a51timrqncr6v3mqr@4ax.com>,
MassiveProng <MassiveProng@thebarattheendoftheuniverse.org> wrote:

>
> Hmmm... I wonder what we could come up with for EEEI.
>
> I have fits of "mild dyslexia", as I call it in my old age as well.

I find a great cure for my mild dyslexia is to start a 100% illegal
electrical project, sharpens one's senses & thought processes y'know,
trying to evade being hauled off to the pokey.

Last week I grabbed the two hot wires from my electric stove outlet.

Voltage here is a bit high, running about 249 vac.

Holding the two hot wires in my teeth, I ran them into my computer den,
40 feet away.

Most of my computer gear will run off of 220 vac, so I slapped the two
hot wires with their 249 vac directly onto the two input prongs of my
big Epson printer.

Printer ran okay even though it is rated for no more than 240 vac,
because there is usually a little leeway in those spec's.

Metal case of the printer measured half a volt to earth ground.

Naturally, after this "proof of concept" stuff, I will clean up the
installation, adding earth grounds, ground-fault circuit interrupters,
arcing detectors, ya-da, ya-da ya-da.

Had a heck of a hard time rounding up a step-down xfmr, to knock my
249vac down to 208 vac.

After many weeks of fruitless searching, I wound up having to get a
custom xfmr wound for $600. It is good for 3,000 VA, which is needed to
drive my 3,000 VA UPS battery backup for my big Mac computer setup.

The mice in the walls of my house are confused, they relied heavily on
the hot wires of my 115 vac wiring to keep them warm during the cold
winter months in these mountains, which is not happening being I
switched to using 249 vac from my stove outlet.

Saw a couple of disgruntled mice packing up and going down the road a
while back, moving to a warmer house.

Mark-

Mark Conrad

2007-02-12, 5:25 pm

In article <8b10t2l4rnvf2gddhe0kr9c2s7fsle38vt@4ax.com>,
MassiveProng <MassiveProng@thebarattheendoftheuniverse.org> wrote:

> I noticed that baggies have more static accumulation faster when
> they are new, as opposed to wrinkled (delibrately).

I use a solid slab of that rigid plastic packing material, then give it
a few swipes with a wool sock to charge it up.

Dang thing pegs my field-effect voltmeter when I hold the sensor
anywhere near the plastic slab. Top reading of the meter is 20 kv.

Estimated voltage on the plastic is about 40 kv.

Only way I can remove most of the charge is to wipe the surface of the
plastic slab with a grounded water-soaked rag, then let the residual
water film air-evaporate.

To charge up small metal objects like metal pots, I sit them directly
onto the charged plastic slab, then touch the pot with an earth ground
wire.

Next I wrap a plastic baggy around the pot handle, so I can remove the
pot from the plastic slab without discharging the pot.

Resulting charge on the pot is well over 10 kv.

Hamster

2007-02-12, 5:25 pm

"Mark Conrad" <noneof@urbusiness.invalid> wrote in message
news:noneof-659B6D.12385611022007@news.west.earthlink.net...
>
> In my 2nd childhood now. This here lec-ertricity is the greatest thing
> since sliced bread to jump-start my ailing 78-year old ticker.
>
> Have one foot in the grave and the other foot on a slippery banana peel.
>
> Heck, just to get going every morning I have to fall down a couple of
> times, to get my juices flowing in the right direction.
>
> Now don't lecture me about safety, I am entitled to play after a
> lifetime of work.
>
> Besides, I live in a rural location where if my house burns down it
> would actually be a service to other residents, because this 50 year old
> house of mine is an eyesore.
>
> Only thing still holding my house together is the fact that all my
> termites are holding hands.
>
> My house wiring is totally shot, various arcing noises and the smell of
> ozone coming from behind my walls.
>
> Has a benefit though, all the mice keep getting electrocuted from the
> bare wires, installed by my house builder because he was too cheap to
> use conduits.
>
>
>
> Back to playing with electricity -
>
> DISCLAIMER - DO NOT try to do this yourself, any one of a number of
> things could go wrong and you would wind up dead. I know what I am
> doing, having worked around high voltages for 34 years
>
> The agenda yesterday called for charging up my small compact car to
> 10,000 volts, as measured by my DC field-effect voltmeter. Got the car
> to 11,000 volts, then let it bleed down to 10-kv for the "test".
>
> Those field-effect voltmeters are fairly accurate, once you learn how to
> use them. For example, I can measure the voltage of a 9 volt battery
> plus or minus one volt, even though the voltmeter is designed for
> measuring voltages up to 20,000vdc.
>
> It is very tough to measure the voltage on small items. About a week
> ago I charged up a small stainless steel pot to 9 vdc, then removed the
> charging circuit.
>
> My field effect voltmeter accurately measured that charge. The voltage
> was not affected by the voltmeter, staying at a constant 9 volts,
> despite repeated measurements.
>
> Over time, of course, the charge on the pot slowly gets destroyed by
> stray ions in the air. After about a half hour there was not much of
> the original 9 volt charge still left on the pot.
>
>
>
>
> Back to the fun 10,000 volt "test" -
>
> Stood with my right foot in soggy ground, then took the full blast of
> the 10,000 volts by grabbing the car door handle with my left hand.
>
> WOW, that will curl your hair, Whatta jolt! Whee!
>
> Lemme see, figure my body resistance was about 5,000 ohms from bare
> right foot to clammy left hand.
>
>
> What was the approximate current through my body -
>
> 10,000 volts, divided by 5,000 ohms = 2 amps.
>
> That means I probably had about 2 amps going through my chest area for a
> brief instant.
>
> I figure the RC time constant was approx' two-and-a-half micro-seconds
> to reach the 63% point of where the voltage drops down to 3,680 volts.
>
> (estimating that the car's capacitance to earth ground was somewhere
> around 500 pico-farads... I did not have the motivation to accurately
> measure it)
>
> Mark-

You know- there's not enough people around like you. Your post probably
explains why ;-)

Keep experimenting. The spirit of Ben Franklin lives on (at least for the
time being)!

S

MassiveProng

2007-02-12, 8:25 pm

On Mon, 12 Feb 2007 20:04:20 GMT, Mark Conrad
<noneof@urbusiness.invalid> Gave us:

>
>I find a great cure for my mild dyslexia is to start a 100% illegal
>electrical project, sharpens one's senses & thought processes y'know,
>trying to evade being hauled off to the pokey.

I start a 100% falsely illegal bong load. ;-]

That places my entire being in a state where the mild dyslexia never
occurs. I find it happens when I am trying to do to much too fast.

MassiveProng

2007-02-12, 8:25 pm

On Mon, 12 Feb 2007 20:04:20 GMT, Mark Conrad
<noneof@urbusiness.invalid> Gave us:

>In article <ui10t2563b8vnsk92a51timrqncr6v3mqr@4ax.com>,
> MassiveProng <MassiveProng@thebarattheendoftheuniverse.org> wrote:
>
>
>
>I find a great cure for my mild dyslexia is to start a 100% illegal
>electrical project, sharpens one's senses & thought processes y'know,
>trying to evade being hauled off to the pokey.
>
>Last week I grabbed the two hot wires from my electric stove outlet.
>
>Voltage here is a bit high, running about 249 vac.
>
>Holding the two hot wires in my teeth, I ran them into my computer den,
>40 feet away.
>
>Most of my computer gear will run off of 220 vac, so I slapped the two
>hot wires with their 249 vac directly onto the two input prongs of my
>big Epson printer.
>
>Printer ran okay even though it is rated for no more than 240 vac,
>because there is usually a little leeway in those spec's.
>
>Metal case of the printer measured half a volt to earth ground.
>
>
>
>Naturally, after this "proof of concept" stuff, I will clean up the
>installation, adding earth grounds, ground-fault circuit interrupters,
>arcing detectors, ya-da, ya-da ya-da.
>
>
>Had a heck of a hard time rounding up a step-down xfmr, to knock my
>249vac down to 208 vac.
>
>After many weeks of fruitless searching, I wound up having to get a
>custom xfmr wound for $600. It is good for 3,000 VA, which is needed to
>drive my 3,000 VA UPS battery backup for my big Mac computer setup.
>
>
>
>The mice in the walls of my house are confused, they relied heavily on
>the hot wires of my 115 vac wiring to keep them warm during the cold
>winter months in these mountains, which is not happening being I
>switched to using 249 vac from my stove outlet.
>
>Saw a couple of disgruntled mice packing up and going down the road a
>while back, moving to a warmer house.
>
>Mark-

Hehehehehe... yer so full of shit... :-]

Toasty mice, indeed.

You could write a book

"Of Mice And A Side of Fires"

Kinda like BlueGill...

MassiveProng

2007-02-12, 8:25 pm

On Mon, 12 Feb 2007 20:04:22 GMT, Mark Conrad
<noneof@urbusiness.invalid> Gave us:

>
>Only way I can remove most of the charge is to wipe the surface of the
>plastic slab with a grounded water-soaked rag, then let the residual
>water film air-evaporate.

Directly laminate, without ANY air gaps, a sheet of AL to one side
of it with a small creepage margin in from the edge. Deburr the sheet
edges so they appear as a rounded edge.

You will find that any charge you apply now (with the sheet up
ungrounded), can be removed pretty darn fast as you have effectively
"wiped" the entire face with the conductor.

I think it is cool that a charged insulator has a bunch of electrons
sitting on one of its faces and the can only be dragged off by a
conductor. Cool stuff.

Maybe you need a toy like this guy has, or a house in Fla that can
give you events like this one (see attachments in ABSE)

Mark Conrad

2007-02-13, 3:25 am

In article <eo32t21ged6o82n9c868mob24q52hofi1j@4ax.com>,
MassiveProng <MassiveProng@thebarattheendoftheuniverse.org> wrote:

> Hehehehehe... yer so full of shit... :-]

Thank you, heavens knows I try to be full of it.

Here is some random stuff I picked up from safety literature:

> 40,000 fires are attributed to home electrical wiring each year.

> Lowest voltage necessary to electrocute someone is 0.2 volts
> (electrode placed directly on heart muscle)

> Worst case resistance across human torso is 100 ohms

> Best case resistance of a manual laborer with palms
> thickened by work and dry hands is 2,000,000 ohms

Way back in my junior high school days, we had an electrical shop
instructor who would grab one wire from 115 vac in his right hand, and
the return wire in his left hand, then stand there smiling at his class.

That guy had very thick calluses on both hands.

'nuff of this nonsense, I gotta go back to work on my anti-matter
propulsion system for spacecraft.

Actually, it is not all that difficult to generate positrons, which are
just positive electrons, on a small scale.

Trick is to do it on a massive scale, suitable for a spacecraft engine.

When a positron collides with an electron, both of them get annihilated,
pure changing of matter directly into energy, none of this inefficient
nuclear fusion crap to propel our spacecraft.

Not all that far fetched. Way back in the 1960s, people at my salt mine
were working on plasma spacecraft engines. (Hughes Research Labs)

Now we have them of course, having been used on the "Deep Space One"
spacecraft.

Eventually they will get anti-matter engines cooking, then the fun will
start, because it could become feasible to mount a project to actually
visit the Alpha Centuri star system, over 4 light years away.

Bound to be an Earth-like planet somewhere in that 3-star system.

We could send 3 spacecraft just for redundancy.

The Nina, Pinta, and Santa Maria.

It would take the better part of 50 years to cover that distance, even
at an average speed of one-tenth the speed of light, powered by an
anti-matter engine.

(66,960,000 miles per hour average speed)

What is the longest time someone has stayed on the Space Station so far,
only a couple of months I believe.

Far cry from actually living on a spacecraft for 50 years.

Then too, we would have those nasty love triangles popping up, like that
astronaut gal recently in the news.

Mark-

Mark Conrad

2007-02-13, 3:25 am

In article <ej32t25rmacp8ver3pg5bhir7vv7kt0eeg@4ax.com>,
MassiveProng <MassiveProng@thebarattheendoftheuniverse.org> wrote:

> I start a 100% falsely illegal bong load. ;-]

Lotsa that going on around here, I have fun running the bonged up
hippies off the road with my Ford 350, watching their bong bouncing up
and down in their mouth as they fight their steering wheels, wheee!

They get back at me later, tho' - - - when I go into the mountains
around here to harvest wild blackberries, they come roaring up in their
pickup trucks with their dogs and rifles hung in the back windows of
their trucks, thinking that I am John Law come to bust their pot farm.

Once they recognize me, then come the friendly greetings:

"Oh, it's just you, you redneck s***head"

Nice to be loved.

After all, farming here is serious business. Half the income in this
state comes from illegal pot farms, not to mention all those additional
jobs created for our very healthy law enforcement agencies.

Let's get serious about Lec-er-tricity.

Didja ever pee on an electric fence? I did once.

Mark-

--
summarizing Underwriters
Laboratories safety criteria for electric fences,
indicated that acceptable output current decreases
with increasing exposure duration. For 5 ms
exposure duration, currents up to 77 mA were
considered safe; whereas for 200 ms exposure,
currents up to only 7 mA were considered safe.
Gettman (1985) considered a current interruption of
750 ms sufficient to allow individuals to break
contact with an energized wire.

Now ya know why I did not get fried by my recent
exposure to 10,000 volts from my charged-up car.

The exposure time was just too brief, even though
about 2,000 mA was flowing through my body.

Takes a while to properly cook an old duffer like me.

John Gilmer

2007-02-13, 9:25 am

>
> That unit has filter capacitors which hold a very substantial 15,000
> volt charge, more than enough to electrocute a careless technician.
>
> He was very lucky, just got knocked on his keester with a very dazed
> look on his face.
>

Years ago in Carnegie Tech (now CMU) "they" had a "bunch" of good sized caps
setting in one of the "machinery" labs. Even then most students didn't
sturdy electric machines anymore.

Anyway, there were "plug" boards for connecting stuff that would not get by
OSHA today. A grad student had set up some kind of "experiment" that
included some "charge" caps.

For some reason, he decided to "pull the plug" going to the cap bank. Had
he just help the single conductor plug the insulation there would have been
no problem. But NO....

He had developed the habit of pushing the panel with his thumb and
forefinger with holding the plug with the remaining fingers and his palm.
When the plug was half way out his thumb can in contact with the conductors.

He eventually recovered, but for a time there were rumors that his thumb had
completely burned off!

Anyway, back to the OP. His "experiments" are no more dangerous (IMO) that
someone rubbing one's feet on the carpet on a cold, dry day.

Mark Conrad

2007-02-13, 1:25 pm

In article <45d19917$0$15576@dingus.crosslink.net>,
"John Gilmer" <gilmer@crosslink.net> wrote:

> Anyway, back to the OP. His "experiments" are no more dangerous (IMO) that
> someone rubbing one's feet on the carpet on a cold, dry day.

Of course my experiments are not dangerous, which is why I have fun
doing them.

Problem is, not all who read these posts have a background in hands-on
electrical work, so they might try a variation of my "fun" experiments,
and manage to get themselves electrocuted.

Such a deadly variation could be a very large metal object sitting on
plastic blocks or rubber tires, on a dry day.

Kinda makes me wonder if airlines take any overt action to discharge
residual electricity before passengers enter/leave the aircraft?

Also keep in mind that electricians as a group have a not-so-good safety
record, due mainly because they work around dangerous stuff constantly.

....but also due to them sometimes getting a wee bit careless. :-/

I myself have a healthy respect for electrical safety, because I worked
for 34 years around it. (not as an electrician, though)

I have seen copper cables 2" in diameter, the copper itself 2 inches,
banging around the rafters of our building like snakes gone wild, when
large industrial generators shorted out.

Umm, did I ever tell ya about the time I wired up a small aircraft for a
friend of mine?

I was having trouble installing the earth ground, but fortunately the
pilot told me he was going to use his airplane exclusively over lakes.

....so I rigged up his airplane with a 1,000 foot long ground wire for
him to drag in the water of those lakes, problem solved.

Gotta run and take my med's now, as I am starting to twitch.

Mark-

John Gilmer

2007-02-13, 1:25 pm

> Such a deadly variation could be a very large metal object sitting on
> plastic blocks or rubber tires, on a dry day.

Nah.

The important "metric" is the area of object that "faced" the ground divided
by the distance of the object from the ground.

I suspect that that ratio is higher with a typical CRT than with any
"reasonable" object and "reasonable" insulators.

Discharging a CRT via one's finger tip definitely get's one's attention but
doesn't kill (yet.)

>
>
> Kinda makes me wonder if airlines take any overt action to discharge
> residual electricity before passengers enter/leave the aircraft?

I suspect (but don't know) that the tyres have enough carbon black to
dischange the aircraft.

>
> Also keep in mind that electricians as a group have a not-so-good safety
> record, due mainly because they work around dangerous stuff constantly.

I know a guy who just doesn't have ANY problem changing a service panel
without pulling the meter. (Hint: he uses a LOT of electrical tape.)
>
> ...but also due to them sometimes getting a wee bit careless. :-/

This guy I know does have his "war stories" (including real war stories from
his service with the USMC in VN.)
>
>
>
> I myself have a healthy respect for electrical safety, because I worked
> for 34 years around it. (not as an electrician, though)
>
> I have seen copper cables 2" in diameter, the copper itself 2 inches,
> banging around the rafters of our building like snakes gone wild, when
> large industrial generators shorted out.

That would be "fun to watch" from a distance.

>
>
>
>
> Umm, did I ever tell ya about the time I wired up a small aircraft for a
> friend of mine?
>
> I was having trouble installing the earth ground, but fortunately the
> pilot told me he was going to use his airplane exclusively over lakes.

OK.

>
> ...so I rigged up his airplane with a 1,000 foot long ground wire for
> him to drag in the water of those lakes, problem solved.

What about the extension cord so he would re-start the engin while flying
with a dead battery?

>
> Gotta run and take my med's now, as I am starting to twitch.
>
> Mark-

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