electric shock question

Thread Starter

maggie

Joined Aug 15, 2011
13
A power line came down on my street, and a neighbor went down and moved it out of the road. He believed it was safe, since the power was out in the houses up the line from the break. i don't know any more than he does, but my logic was, maybe there could still be enough voltage to kill a human, and maybe the transformer still has a charge, and it's just not a good idea to go near it. Now that he succeeded in moving it without a problem, he is even more convinced that he's right and I'm a big worry wart. This may be more an electrical issue than electronics, but maybe there's an EE out there willing to explain this to me.
 

MrChips

Joined Oct 2, 2009
19,911
If the power was out, there would be no residual electrical charge in the cable. However, if the power was being restored while he was in the process of moving the wire he probably would not see the light of day.

You were correct. It is best to leave power lines to the proper folks to handle, power out or not.
 

#12

Joined Nov 30, 2010
18,167
On a more technical note, transformers do not retain charge, but capacitors are often used for phase compensation, and one of them could remain charged, depending on exactly which connections were destroyed and in what order.

You were correct. There are people that do that kind of job safely, and it's not an average citizen. Even I would not touch a fallen power line, and I'm good at this!
 

hgmjr

Joined Jan 28, 2005
9,029
A power line came down on my street, and a neighbor went down and moved it out of the road. He believed it was safe, since the power was out in the houses up the line from the break. i don't know any more than he does, but my logic was, maybe there could still be enough voltage to kill a human, and maybe the transformer still has a charge, and it's just not a good idea to go near it. Now that he succeeded in moving it without a problem, he is even more convinced that he's right and I'm a big worry wart. This may be more an electrical issue than electronics, but maybe there's an EE out there willing to explain this to me.
Handling of high voltage power lines is not a wise activity. The only safe assumption is that the line is potentially lethal. The safest thing to do is report the downed power line to your local power provider and let them deal with it.

hgmjr
 

GetDeviceInfo

Joined Jun 7, 2009
1,661
That would have been extremely foolish. Often, local breakers are configured to try and automatically reset once or twice. Unless he knew without a doubt that the local switches were pulled, approaching the line would be foolish.
 

steveb

Joined Jul 3, 2008
2,436
This may be more an electrical issue than electronics, but maybe there's an EE out there willing to explain this to me.
There is not much to explain, other than the fact that your neighbor was stupid to touch the line. No EE in their right mind would have done that, no matter how good their understanding of electricity, and no matter what knowledge they had about the state of the voltage on the line.

The people that work on those lines are highly trained and have the right tools for the job. It's that simple.

Not too long ago I read about a high voltage line that went down. If i remember correctly, three people died. A father went out to look and was electrocuted even without touching the line. The son ran out to help him when he saw him fall and was also killed instantly. I believe one more person (maybe his wife) did the same and payed the ultimate price.
 

bluebrakes

Joined Oct 17, 2009
245
i've seen some nasty pictures of people being fried until all of their bodily fluid has been boiled out of their bodies due to their ignorance of the dangers of high voltage.

You were right, a really dumb thing to do. He's going purely on assumptions and very stupid indeed.
 

Adjuster

Joined Dec 26, 2010
2,148
The fact that there was a power outage in the area does not guarantee that a given broken cable was dead at the time, nor that it would stay dead. For instance, unless he had very definite knowledge of what constitutes upstream and downstream in the system, how could this fellow be sure that it was not the disconnection of that very cable which had caused the fault in the first place?

The point about fault restoration, automatic or otherwise, is a good one. Just thinking about it makes me feel uncomfortable.
 

Arius007

Joined Sep 2, 2011
14
As well as the risks already mentioned there is another system used on Medium/High Voltage lines called (in some places) auto-earthing - if it detects a line down it can connect that phase to earth. It can also reset itself if the conductor is removed from ground, so the line is at zero volts potential, you pick it up, the auto-earthing resets and you're left holding a HV cable.

Something else not mentioned yet is Step Voltage which is the voltage that you can pick up between your two feet while being close to the conductor - it's not necessary to touch it to get fried!

Bottom line is you don't touch it until you've solid confirmation that it's been properly isolated and you won't get this confirmation unless you're working for the company that owns the line.
 

t_n_k

Joined Mar 6, 2009
5,447
Something else not mentioned yet is Step Voltage which is the voltage that you can pick up between your two feet while being close to the conductor - it's not necessary to touch it to get fried!
I think that's what steveb was suggesting in his anecdote in post #6
 

Thread Starter

maggie

Joined Aug 15, 2011
13
Thanks to everyone who posted on this. You all gave me plenty of reasons I had not thought of. I think I discovered the difference between ignorance and stupidity. It's ignorant to do it the first time, but thinking that doing it once proves you know what you are doing, really shows lack of intelligence.
 

Thread Starter

maggie

Joined Aug 15, 2011
13
WoW! another not so bright idea. She might have lived but there was smoke coming out of her head! I'd like to know if there were any after effects. Maybe epileptic seizures, or crazy new math skills?
 
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