On Tue, 11 May 2004 08:33:47 -0700, Adam Russell wrote:

"bill" wrote in message
news:MPG.1b0a4f6d199ad699989713@localhost...

Your static charge is DC.

Disagree. DC means unchanging voltage. Static charge changes as soon as it
is 'used'. Otherwise I agree with what you say.

Disagree all you want, but he's right. It's a DC voltage that decreases
as it's discharged through a resistance (you), just like any other DC voltage.

The fences probably use a capactive discharge circuit.

This makes sense. Good jolt but relatively safe.

....which is also DC, just like a static charge or lightning, but
somewhat between the two.

"Adam Russell"
|
| Your static charge is DC.
|
| Disagree. DC means unchanging voltage. Static charge changes as soon as
it
| is 'used'. Otherwise I agree with what you say.
|
| The fences probably use a capactive discharge circuit.
|
| This makes sense. Good jolt but relatively safe.

As a retired EE : DC means only direct current (as compares to alternating
current) it does not mean unchanging. (an over simplified example: If you
car has a volt meter watch it when the motor is off and when the motor is
running.)

I grew up on a farm, and as kids we grabbed the fence tons of times when we
thought it was off. It hurt like hell, but it didn't kill us. Just sent us
crying to mom.

In fact, I can remember (vividly, no less) one dusk when we were playing tag
across the pasture, and I practically garrotted myself on a wire gate that I
thought was open. Caught the wire (between barbs, thankfully) right under
the chin, and both feet went out in front of me.. *wham* "I don't
want to play, anymore."

--Goedjn

you can die from as little as 50v. Even less if you got imaginative.
Voltage doen't kill you, current does. You get hit a lot of
voltage when zapped with static electricity, but very little
current.

Yes but they dont use static electricity in electric fences, do they?


The cattle fences that I grew up with sent very short pulses
about once a second, at several thousand volts, and some
really low amperage. And if you're getting zapped by
electricity, it's not static anymore...

On Tue, 11 May 2004 13:54:53 -0400, wrote:


I practically garrotted myself on a wire gate that I
thought was open. Caught the wire (between barbs, thankfully) right under
the chin, and both feet went out in front of me.. *wham* "I don't
want to play, anymore."

Heh. I did pretty much the same thing years ago when I was a brand-new,
shiny EMT. Responded to a car accident; the car had run off the road,
through a barbed wire fence, and overturned, scattering it's un-belted
occupants. Things were going really well in my getting to them, until
I encountered the part of the barbed wire fence which was still
intact. Nice scars, one on my upper arm, another on my chest. I didn't
mention it to anyone at the scene, or I would have got that year's award
at our annual party, for sure.

Fences, plus dark, plus more speed than visibility, are a bad combination.

Dave Hinz

In article ,
says...



Your static charge is DC.

Disagree. DC means unchanging voltage. Static charge changes as soon as it
is 'used'. Otherwise I agree with what you say.

The fences probably use a capactive discharge circuit.

This makes sense. Good jolt but relatively safe.




No, DC means Direct Current as in flowing only in one direction.
Under your definition, batteries aren't DC because eventually they
go dead.

Bill

"Adam Russell" wrote in message ...
"Snooze" wrote in message
. com...
Don't let your kids wear wool socks on a low humidity day...imagine what
would happen if they discovered they can shuffle around the house and zap
each other with a few thousand volts. A typical static electricity shock
is
about 2000 - 4000 volts.

Of course a amperage involved is so low, that aside from the surprise, no
damage is done. Ever taken a weak 9v battery and tapped it against your
tongue? A fresh battery hurts a little, but a weak one gives a little
tingling sensation.

A consumer grade electric fence is harmless, it will give a mild shock,
but
nothing dangerous. I couldn't find the specifications online, so
guestimating, if an electric fence transformer draws 120v A/C @ 1 amp, the
output would be 4000 v A/C at .03 amp.

That's just a mild shocker, pretty safe..if it was D/C on the otherhand is
a
different story.

You dont know much about electricity it appears. Static electricity is
completely different from transformer electricity. When you get a shock
from static electricity it is 2-4k for only an extreme fraction of a second.
I dont remember how short exactly (1ms comes to mind), but it is the brevity
that saves you. As it swiftly runs out of electrons the voltage falls to
zero.

Somehow I doubt it's the brevity that makes static electricity
harmless. I've played around with battery-powered circuits that work
by delivering pulses of electricity to the subject when the current
through a circuit containing an inductor is interrupted (for example,
the gag lighters that shock people work this way). Whatever current
is flowing through the inductor gets sent through the subject for a
short period of time. It's relatively safe because the peak amperage
is controlled. If you hook up a resistor in series with the subject,
the maximum current doesn't change, but the pulses get shorter. When
you do this, the pain falls off, but the response from your muscles
doesn't change as much. Eventually, especially if the contact area
between the electrodes and the skin is large, you can produce
involuntary muscle contractions with little or no pain.

Given that the heart is a muscle, I would think that a few seconds of
current would be better than a few milliseconds if the goal was to
produce pain without rendering any permanent harm. I could be wrong,
but if I had to guess, I'd say the reason static electricity isn't
harmful is because most of the voltage is across the air gap, not
across your body. Also, the charge is entirely on your skin, and most
is probably very close to the spot where you're about to touch
something, so practically no current is going through your heart.

Power out of your wall does not fall off. At all. That 120v will
deliver 1mA or 15A depending on the resistance of what you are powering and
only limited by your circuit breaker or fuse. If you were to put a penny in
the fusebox it could deliver 1000's of amps with no problem except that the
wires would get hot. So putting it through a transformer will not reduce
the amperage available to any safe amount. 4000v will kill you, and it
matters not whether it is DC or AC.

Surely it couldn't be very difficult to have a device of some sort in
the circuit to control the maximum current. At the very least,
couldn't he just put an appropriate fuse in the circuit, if there
wasn't one already?

Now as to the matter of electric fences, when I was a child my grandpa told
me to stay away from the electric fence surrounding the cow field. He said
it would kick me like a sledgehammer. He could have been pulling my leg,
but I imagine that anything meant to coerce a cow would hurt a human. OTOH,
a raccoon is not a cow. The question is open whether you could make a fence
with enough jolt to keep out racoons but not enough to hurt 3 year olds. I
personally doubt it.

There's almost one order of magnitude between the current needed to
cause pain and the current that's large enough to be dangerous. The
fact that the area of contact with the wire is small, and a three-year
old is larger than a racoon, ought to make the range of safety even
broader.

Jim Black wrote:


Somehow I doubt it's the brevity that makes static electricity
harmless.

Who said static electricity is harmless? Lightning is static
electricity, but I don't see many people standing outside in a thunderstorm.

But what do I tell customer service if the cocktail holder breaks!?!?


"Doug Kanter" pontificated wisely that:

"rot13 (Kevin Miller)" wrote in message
...


I would not use an electric fence with a 3 year old kid in the house.

Given that the racoons are nocturnal you would only need to turn the
fence on at night when presumably your 3yr old would be inside.

You have just won a virtual cocktail for noticing something nobody else did.
Place glass in CD-ROM drawer and hit:
CTRL-M (for real beer - Molson)
CTRL-B (for water - i.e.: Budweiser)
CTRL-J (for Jack Daniels)



Kevin Miller
(rot13)
http://www.net1plus.com/users/miller9

Ignoramus27199 pontificated wisely
that:

In article , rot13 wrote:

Given that the racoons are nocturnal you would only need to turn the
fence on at night when presumably your 3yr old would be inside.


I can second the recommendation for Premier. Their customer reps are
very helpful and knowledgable. I called when I was setting up fencing
for our goats planning on getting a fancy combination of electric twine,
HT wire, fiberglass line posts, metal corner t-posts and a solar-battery
energizer. After asking what I wanted the fencing for their rep
suggested electric netting, some plastic corner posts and an energizer
with 9v alkaline battery. Saved me a bunch of money and I've been very
happy with the system.

You see, my spouse would never agree to it no matter what physics
based explanations I offer.

I hear ya, but things do sometimes change. My wife would never agree to
any kind of gun around, until she chased a fox away from her hen house.
Then I discovered that our state laws were such that an air rifle was
the only practical solution.
Kevin Miller
(rot13)
http://www.net1plus.com/users/miller9

In article , Advanced Priority
wrote:

Jim Black wrote:


Somehow I doubt it's the brevity that makes static electricity
harmless.

Who said static electricity is harmless? Lightning is static
electricity, but I don't see many people standing outside in a thunderstorm.

How well I remember shuffling across the carpet & pointing my finger at my
sister's head, giggling until -- FLASH! -- both of us fell into fits of
tears. And that's why to this day I have but nine fingers & my sister went
blind & became bald for life.

-paghat the ratgirl

--
"Of what are you afraid, my child?" inquired the kindly teacher.
"Oh, sir! The flowers, they are wild," replied the timid creature.
-from Peter Newell's "Wild Flowers"
See the Garden of Paghat the Ratgirl: http://www.paghat.com/

Advanced Priority wrote in message ...
Jim Black wrote:


Somehow I doubt it's the brevity that makes static electricity
harmless.

Who said static electricity is harmless? Lightning is static
electricity, but I don't see many people standing outside in a thunderstorm.

Oops ... but you know what I meant -- static electricity at around
2000 - 4000 volts, as was being discussed. Practically everything is
lethal if you get enough of it.

"Adam Russell" wrote in message
...
You dont know much about electricity it appears. Static electricity is
completely different from transformer electricity. When you get a shock
from static electricity it is 2-4k for only an extreme fraction of a
second.
I dont remember how short exactly (1ms comes to mind), but it is the
brevity
that saves you. As it swiftly runs out of electrons the voltage falls to
zero. Power out of your wall does not fall off. At all. That 120v will
deliver 1mA or 15A depending on the resistance of what you are powering
and
only limited by your circuit breaker or fuse. If you were to put a penny
in
the fusebox it could deliver 1000's of amps with no problem except that
the
wires would get hot. So putting it through a transformer will not reduce
the amperage available to any safe amount. 4000v will kill you, and it
matters not whether it is DC or AC.

Now as to the matter of electric fences, when I was a child my grandpa
told
me to stay away from the electric fence surrounding the cow field. He
said
it would kick me like a sledgehammer. He could have been pulling my leg,
but I imagine that anything meant to coerce a cow would hurt a human.
OTOH,
a raccoon is not a cow. The question is open whether you could make a
fence
with enough jolt to keep out racoons but not enough to hurt 3 year olds.
I
personally doubt it.

Most fence chargers work on pulses. You get zapped, but that's all it
is...a zap. You have plenty of time to let go before it sends another
pulse...and you tend to let go in a hurry.

A 3 year old would be fine with the fence...just like the cows...one zap and
they develop a healthy respect for it.

jena

"JMartin" wrote in message Most fence chargers work on pulses. You get
zapped, but that's all it
is...a zap. You have plenty of time to let go before it sends another
pulse...and you tend to let go in a hurry.


Very true unless you're like me. A number of years ago I kept a horse at a
neighboring property, the field surrounded by an electric fence about two
feet off the ground. In a small area with a lump in the ground, I would
step over the fence to take a shortcut to the barn. Once, in shorts my
inner thigh caught the fence. As I danced back and forth, getting each leg,
I finally jumped high enough to clear it. It hurt but more of a
slap/surprise kind of hurt. I must have looked so silly dancing over that
fence grin
Sue
Northern Wisconsin

paghat wrote:


How well I remember shuffling across the carpet & pointing my finger at my
sister's head, giggling until -- FLASH! -- both of us fell into fits of
tears. And that's why to this day I have but nine fingers & my sister went
blind & became bald for life.

-paghat the ratgirl

Did your sister become a lesbian, too?