I would think that their double check would be to double check that the circuit (line) in question is actually switched off, and that there would be strict protocolls for that double and triple check.



Have a look at the insulators, those thingies that keep the lines off the poles. They're quite big and with lots of dishes that serves the purpose of increasing the distance along the surface (highly relevant when they're wet). That should give you some idea about what you're dealing with.

Insulation on the wire itself would hardly matter for a line in the kilovolt range.

With live kilovolt wires on the ground there essentially are no safety parameters to speak of. Too many variables, too high voltage.

Arching is not nescessary for killing you. No arching does not in any way imply that the area is safe - just that there is no "bzzzt" sound to warn you.

I want to add to Susan's post about evacuating a burning vehicle around downed power lines - definitely a very last resort, since the odds of making ground contact in the wrong way are very high, and you will be electrocuted. If you land on your two feet and manage not to be electrocuted, Puget Sound Energy recommends shuffling away from the scene - do not lift either foot off the ground. I understand that breaks the possible circuit and the electric charge will end somewhere in your body, probably your heart. In fact PSE recommends shuffling away from any downed power line you may have approached on foot - don't take any chances, you might have come close enough to get power running through your body, or the electric field may have shifted on you. It only takes a hair dryer in a bathtub to give you a hard enough shock to kill you, don't mess around with downed wires.

Every time there's a question involving electricity I regret not paying better attention in physics, or in auto shop. All I know is to stay away, alert help, and keep others safely away too. In almost any scenario that works for folks, especially here in the PNW after our windstorms.

As for the other obscure and hypothetical scenario offered by someone else (wife pregnant, child in car, help more than 4 hours away) - stay in your car, call 911. If you wife goes into labor, deliver the baby. If your car catches fire, do your best to put it out. If it continues to burn and you with it, you must all leap and take your chances, just like in Susan's scenario. Prepare to watch at least one of your loved ones electrocuted if you let them leap first. You are safer for the next four hours in a burning car with a woman in labor than you are leaving the car before help arrives to deal with the downed power lines and rescue you.

I have an electrical engineering degree, paid attention in class, and got good grades. My thoughts are that every electrical problem has its own unique characteristics. Also, our lab experiments were a humbling experience. Electricity is many times unpredictable. You can fully understand the theory of electronics. Then, you step into the lab and realize that your theory is more like a general guideline of how electricity will behave.

In this situation, there are general guidelines to be safe. However, the consequence of being wrong is not receiving a "C" on a lab assignment. The consequence of being wrong is killing somebody. Accordingly, the best answer by far is to advise somebody to stay away and how to do stay away safely. The next best answer is to advise the person to get a job with the local electric company and learn the trade of dealing with downed power lines. I would NOT put my name on any other answers if you knew me in real life.

Hey another EE!! Power transmission wasn't my focus in school but I did well in the class and did focus on EM fields (and also did quite well). Those classes were a long, long time ago but they did a good job of making me very very aware of why only trained professionals should deal with downed power lines.

High Power electrical fields are tricky beasts and mistakes are often fatal. The theory is pretty straight forward but practical application depends on a lot of variables. Without the right equipment and training the only real answer is stay away and call for help.

Just to add a further note of caution. For a 115KV line shorted to ground the voltage drop from 1 foot away from the ground point to 4 feet away (one step) can be nearly 700V differential, depending on soil conditions. That is why PGE and others suggest shuffling away if you find yourself near downed lines. Similarly the voltage drop from 10 feet to 13 feet will be in the 130V range. That means you really want to be at least 60 feet away from any downed lines since you won't know the voltage level or the ground conditions.

-Eric

OK, I'm game.
I wouldn't call her Charlie, I'd call her by her name. And I don't have a kid. But, really, why are they stuck and I'm not?

Easy answer: call the power company. they can kill power to that area (ideally you have the pole number, but if not, hopefully they can figure out the road). And, oh yeah, 911 will help too, since the fire engine's typically carry lineman's gloves. Don't think they'll just mosey over and pick up the line, though! AFAIK, you don't need a lineman to turn the power off, you need a lineman to repair the line.

If I can't get to them, power can't be turned off, then yes, I'm sorry, but you'll have to ride it out.

To the OP - that WAS good advice. Stay the heck away from power lines.

Edit: Actually, it'd be interesting to get DR's input on this. Or a professional lineman.

Thanks for the information in the third paragraph of your post, Eric.

-john

Yeah, that was actually good info.

Yes there is a way....THEY ARE ALL LIVE!!!!! Don't risk it.

The consensus answer seems to be there is no safe way for non-experts to determine if a downed power line is live or not.

So, assuming we should treat all downed power lines as live, if we must encounter them to survive, how do we do it?

Stay way, way, way far away from them!! Seriously, distance is your friend and more is better, much better.

If that isn't really possible then you need to be very well insulated and not become part of the shortest electrical route to ground. Rubber is a very good insulator (assuming it isn't "contaminated" by a conductor or have any teensy tiny little holes in it.). In this case thicker (to a point) is better. If you have a choice dry is always better than wet. Voltage drops can be amazingly high even over short distances so keep feet close together (i.e. shuffle) and don't touch anything with your hands etc.

For local transmission lines (relatively low voltages say < 600V) a long length of dry rope (nonconductive) or dry wood (kiln dried preferred) along with some good rubber gloves and boots might let you move a line and live to tell the tale but I generally wouldn't have anything I would trust my life to in my home, much less in the car or in my backpack. Above that voltage level it really becomes a matter of needing the correct gear.

Realistically, I wouldn't trust anything I could buy at the local hardware store, lumberyard or super do-it-yourself store. There are places that sell certified inspected gear to linesmen (and I assume lineswomen). If you want or need to plan for this scenario you should find high quality (read that as professional/certified) gear specific to your needs and take the time to learn the appropriate/applicable standards along with the risks and techniques.

Personally I have decided the risk/reward and probability equation makes this something I won't ever plan for. Kind of like trying to figure out which wire to cut on the tamper resistant bomb some one left on my doorstep. I'll go down swinging but figure it won't matter which wire I cut, it will either work or I'll never know.

Please, please be careful around downed power lines.

- Eric