Maker Pro
Maker Pro

Downed power lines

  • Thread starter Abstract Dissonance
  • Start date
D

David L. Jones

Jan 1, 1970
0
Abstract said:
It was a hypothetical... surely you could easily have picked up this if you
read the very first line?

Ok, so it's hypothetical, but that doesn't change the answer!
There are a dozen or more variables involed in such a scenario, any one
of which could kill you. Your question is just to general to give an
answer other than don't touch it. Even if you have a detailed
hypthetical scenario, one simple overlooked detail is enough to kill
you.

Hypthetically speaking, attempting to ground the wire is probably the
*worst* possible thing you could attempt to do. Even if you had the
"correct" equipment and the training, you'd still have to thoroughly
evaluate the given scenario before attempting to do anything. The
energy in a power line can be incredible, and as others have said,
there is a massive risk in attempting to ground something like this.

If I was in that hypthetical scenario and I just *had* get to across
those power lines, I would not even think about grounding them, or
moving them with a long wooden stick or whatever, I'd probably just
take a big running jump and attempt to clear them. After I have checked
there isn't a breaker down the street, another way around etc.

I know that you think there must be a "technical" answer to your
"hypothetical" question, but there just isn't, the scenario's are just
too complex. The best technical answer is simply "avoid at all costs".
Try to live with that.

Dave :)
 
A

Alan B

Jan 1, 1970
0
Seriously, approach cautiously, if it tingles too much, and your hair is
standing on end then back off and try a longer stick.

Better re-read what I said about step potential. It's got nothing to do
with the hair on your head. Hair on your balls, maybe, if you had any. It
comes in around thirteen.
 
D

David L. Jones

Jan 1, 1970
0
Abstract said:
Nope, What I was after if the general principle was right. Now, any
electrical engineer who actually learned something in school could easily
answer the question. He would also not hesitate go through powerlines if he
knew how to ground them.

That is where you are completely wrong.
Any electrical engineer worth their salt would not even think about
attempting to ground a high tension power line.

Sure, once the lines *are* grounded, it's potentially safe (no pun
intended). But how you ground those lines properly depends on the
individual scenario which simply cannot be throughly discussed here.
The real problem is that you get so easily confused if the context of the
problem is not to your liking. What you need to do is abstract it and
realize that it has nothing to do with power lines but its just a general
electricity question. If I would have said it in a more appropriate context
for you then the answer would be obvious.

It *cannot* be reduced to a simple "general electricity question", this
involves high voltage and high energy power lines where it is the
practical implementation details that matter! You cannot extract and
ignore the practical details with this sort of stuff.

Dave :)
 
A

Alan B

Jan 1, 1970
0
Also that the downed line would
only have a percentage of its nominal voltage that it had when it was up on
its insulated, far above ground, proper place.

You don't know squat about HV transmission lines. One can only hope that
no-one, not even yourself, ever takes your talk on the subject seriously.
 
D

Don Bruder

Jan 1, 1970
0
Alan B said:
That's a very bad assumption. The better assumption is that the ground is
already somewhat live just by being covered by a live line. "vic"'s
somewhat facetious comment about hopping on one foot covers the situation
aptly: one would be foolish to even walk near a downed line, for the
voltage gradient *on the ground* from one footstep to the next may very
well be sufficient to kill or maim. It's called "step potential."

I just recently saw another mention of this somewhere else for about the
4th-5th time - When, however insanely, you find yourself approaching a
downed line, either hop or shuffle small steps to minimize the effects
of field gradients between contact points. Don't *KNOW* if it's fact or
fiction, and am unlikely to find myself in a situation to test it, but
I've *HEARD* it a few times, and it DOES make a modicum of sense at
first glance.

It also pretty much fits with what I know from associating with a
lineman whose primary trade during his active years with Consumer's
Power of Michigan was "High Voltage Lineman" - He worked on the *BIG*
boys that *NEVER* go cold short of being cut. Working 500KVA lines with
them hot was his bread and butter. He told me many a tale, and a LOT of
practical info, and the advice to shuffle or hop meshes with his
teachings, common sense, and what I already knew of
electronics/electricity even before meeting him.

A 1V potential between contacts is no big deal - But what about a 500V?
Or higher? Methinks "Ouch" be de answer.
 
D

Don Bruder

Jan 1, 1970
0
BobG said:
My buddy Billy has 30 years at the power company. They show em a safety
film about how to deal with a live wire falling on the truck.... jump
out! Don't step out!

Ayep! Applies equally to teardown night at the carnival, with the rain
coming down in buckets: *DON'T TOUCH THE RIDES AND THE GROUND AT THE
SAME TIME!* You need to get onto a ride? Jump to it. *DO NOT* Climb
aboard it unless you want it to knock you on your ass. You need off a
ride? Jump. Failure to follow those simple rules was a guaranteed trip
to "DAMN! That one got me good!"-ville - Assuming you didn't v-fib.

One of the reasons we did our damnedest to avoid setups or teardowns in
the rain if we could possibly help it. It was a stone bite trying to
work on a hot ride after the cover and scenery came off, exposing all
the various electrical gizmos, all at 240 and above.
 
G

Guest

Jan 1, 1970
0
I smell a business opportunity here. I will take advantage of the terror
shown here by offering to deal with high voltage---for a price! An arm and a
leg maybe. And the power company guys will go along once they find out what
their service is worth to people who are to terrified to even allow
speculative discussion.
 
R

Rich Grise

Jan 1, 1970
0
I'm curious as to how one, say if they are forced to, approach downed power
lines.

It depends on who's forcing you. If you're better armed than they are,
then don't.

Good Luck!
Rich
 
R

Rich Grise

Jan 1, 1970
0
What gets me is that some of you guys are somewhat intelligent but can't
understand that I was asking a hypothetical. Its not like I'm going to
go try test out any responses.

What, are you upset that you've asked a "hypothetical" question, and got
real answers?

Hypothetically, you could levitate over it, or move it by telekinesis.

But I'm wondering, in this hypothetical universe of yours, what could
possibly possess any sane person to approach a downed power line, and what
kind of creature would hold you at gunpoint and force you to electrocute
yourself?

Thanks,
Rich
 
B

Bobo The Chimp

Jan 1, 1970
0
Nah, he can't find the '11' on his keypad.
 
R

Rich Grise

Jan 1, 1970
0
Jesus christ.. did you not read? IT WAS A FUCKING HYPOTHETICAL!!!


OK, here's the plain facts.

Hypothetically, you will die.
In real life, you will die.

Is that simple enough for you?

Thanks,
Rich
 
A

Alan B

Jan 1, 1970
0
I just recently saw another mention of this somewhere else for about the
4th-5th time - When, however insanely, you find yourself approaching a
downed line, either hop or shuffle small steps to minimize the effects
of field gradients between contact points. Don't *KNOW* if it's fact or
fiction, and am unlikely to find myself in a situation to test it, but
I've *HEARD* it a few times, and it DOES make a modicum of sense at
first glance.

Trust me, it's a fact. Voltage gradients and step potential are very real,
and potentially very dangerous. Here's an interesting presentation:

http://nwhydro.org/downloads/Heartbeat_2005.pdf

Or, just do a search on "soil resistivity" "step potential" and "fault
current," and see all the interesting reading available!
 
A

Alan B

Jan 1, 1970
0
I smell a business opportunity here. I will take advantage of the terror
shown here by offering to deal with high voltage---for a price!

You betcha. We could see how much my company would pay you (well, your
beneficiaries) to demonstrate the falsehood of step potential, after
they've spent untold millions educating their workers about its reality.
We could maybe get three, four, or even five camera angles. You'd be
famous! Heh. Well, maybe you could get away with that sort of spectacle
in a third world country. <sniff> Do you smell burned meat?
 
A

Abstract Dissonance

Jan 1, 1970
0
Don Bruder said:
I just recently saw another mention of this somewhere else for about the
4th-5th time - When, however insanely, you find yourself approaching a
downed line, either hop or shuffle small steps to minimize the effects
of field gradients between contact points. Don't *KNOW* if it's fact or
fiction, and am unlikely to find myself in a situation to test it, but
I've *HEARD* it a few times, and it DOES make a modicum of sense at
first glance.

It also pretty much fits with what I know from associating with a
lineman whose primary trade during his active years with Consumer's
Power of Michigan was "High Voltage Lineman" - He worked on the *BIG*
boys that *NEVER* go cold short of being cut. Working 500KVA lines with
them hot was his bread and butter. He told me many a tale, and a LOT of
practical info, and the advice to shuffle or hop meshes with his
teachings, common sense, and what I already knew of
electronics/electricity even before meeting him.

A 1V potential between contacts is no big deal - But what about a 500V?
Or higher? Methinks "Ouch" be de answer.

That is basically my point though. We learn about certain principles in
basicl electronic courses but I'm curious as if they still hold on higher
voltages. The breakdown voltage of air, I think, is 32kV/in... so if your
dealing with something at 500kV then thats more then a foot away that it
could "get" you.

What made me ask the question in the first place was I saw on tv some
reporters walking over a HV line that was downed. Now maybe there was no
power in it but I was curious as to why they did it when it was possible
they could have died.(and there surely wasn't any electricians around to
tell them it was ok to do so).

Now, some assholes here has to try and start a pathetic argument to get out
of answering the real question I asked... maybe because they don't know and
they just don't want to admitt it or not even post.

The main thing I'm after is how these people work around HV such as power
lines. Obviously the easiest answer is just to shut off the power... but
surely there would be a case where that might not be possible(its not hard
to imagine... unless maybe you are John Fields).

Anyways, I can see the dogs have taken over this thread so its become
useless but atleast some people like you are atleast offering some
reasoning. Maybe its just to hard for John Fields to think about
hypotheticals?
 
G

Guest

Jan 1, 1970
0
Sorry, I can't discuss valuable proprietary info, except to say tools and
techniques can be developed to deal with anything, (unless you naysay before
you try).
The power company already deals with downed power lines so don't tell me, or
anybody, that it can't be done.
The power company already deals with downed power lines so don't tell me, or
anybody, that it can't be done.
The power company already deals with downed power lines so don't tell me, or
anybody, that it can't be done.
Everybody except some of the people in this newsgroup knows that the power
company deals with downed power lines and IT CAN BE DONE.
 
D

David L. Jones

Jan 1, 1970
0
Abstract said:
That is basically my point though. We learn about certain principles in
basicl electronic courses but I'm curious as if they still hold on higher
voltages. The breakdown voltage of air, I think, is 32kV/in... so if your
dealing with something at 500kV then thats more then a foot away that it
could "get" you.

Take a look at the big 500KV power lines and take note of how they have
insulators that are a *lot* longer than a foot.
Notice also how the ceramic isulators aren't just straight, they are
bell shaped, that is designed to create an even longer path that the
voltage must break down over.

What makes power lines different is the *massive* amounts of power
available, power that can make metal and human bodies explode. Serious
stuff, and a lot different to lower voltage stuff. Your power point
mains is dangerous enough, if you accidently short it out it can easily
blow a hole in your screwdriver or cutters etc.

That is why your suggestion of trying to ground a live cable is just
shear madness, even hypothetically speaking.
What made me ask the question in the first place was I saw on tv some
reporters walking over a HV line that was downed. Now maybe there was no
power in it but I was curious as to why they did it when it was possible
they could have died.(and there surely wasn't any electricians around to
tell them it was ok to do so).

They did it because they are dumb-ass TV reporters, their IQ does not
reach triple digits.
Now, some assholes here has to try and start a pathetic argument to get out
of answering the real question I asked... maybe because they don't know and
they just don't want to admitt it or not even post.

We have answered your question. *Don't* attempt to ground the cable!
Keep away until they power can be safely shut off.
The main thing I'm after is how these people work around HV such as power
lines. Obviously the easiest answer is just to shut off the power... but
surely there would be a case where that might not be possible(its not hard
to imagine... unless maybe you are John Fields).

They not only isolate the power at multiple ends, they also *properly*
ground the cables *after* they have been shut off, just in case someone
gets through all the safeguards (multiple padlocks) and turns the power
back on, or another live cable falls on the one they are working on
etc.

Dave :)
 
Y

Yukio YANO

Jan 1, 1970
0
Abstract said:
was grounded properly and properly attached to the power lines but is theres
something I'm missing?

Thanks,
Jon

What are you missing !!!

You failed to account for the powerful Magnetic Fields generated by an
ARCING conductor !

I once witnessed a downed power line on a Main street in a big city.
It whipped like an angry snake every time it shorted to Ground.

If this wire was not grounded it would appear totally harmless, once it
completed a circuit, it would be to late to beat a hasty retreat.

I once attempted to Arc Weld using a CARBON rod and a 12 Volt battery
and was surprised by the reaction of the battery cables to the Current Flow.

Yukio YANO
 
Y

Yukio YANO

Jan 1, 1970
0
Abstract said:
Anyways, I also remember seeing osmethign on TV a few years ago where a
power line worker was in a helicopter and his job was to do something with
the lines. Somehow he got shocked when he was doing what he was doing(I
forgot)... normally it doesn't happen but I think it was cause of something
stupid.

Thanks,
Jon

He got Zapped by the STATIC ELECTRICAL Charge generated by the Rotor of the Helicopter, not from the power Line.

He failed to ground himself to the power line !!!

Yukio YANO
 
P

Puckdropper

Jan 1, 1970
0
Jesus christ.. did you not read? IT WAS A FUCKING HYPOTHETICAL!!!

If you don't know what that word means then look it up in the
dictionary.

The only idiots in here I see are the ones who can't understand what a
hypothetic is.

I guess you never watched MacGyver?

Hypotheticals can be tricky to answer and pose danger. It's possible
that some impressionable person reads the answers and comes across the
hypothetical situation you described and attempts to implement the
solution. How do you ground the wire? Well, first you pick it up...

Oh, and MacGyver would probably go under the conviently placed truck that
shelters him from the power lines, then he'd use the power as a voltage
source for some explosion with some conviently abandoned science lab
where they didn't take all the stuff. (At times, it got a little /too/
convient.)

Puckdropper
 
Top