Determining if downed power lines are live?

We had a windstorm a while back that downed a number of power lines. This made quite a maze of roads that were and were not blocked.

But, I could imagine if the storm had been a bit worse, that it could be much more difficult to travel without crossing some downed lines.

Is there any safe way to determine if a downed line is live or not?

-john

What's the emergency that you would consider driving over downed power lines? Turn around and go back to an open area and park. If you're headed home, tell Honey you'll be late. If you're going to work, tell them you'll be late or you're sick. If you're bleeding heavily or your labor contractions are less than two minutes apart, you shouldn't be driving, anyway.

If you insist on driving over live power lines, your car is wearing studded tires, and you survive, be sure to post here and tell what happened to the tires. I've always wondered what would happen.

But this looks like some good advice:

"If you must drive, be watchful for downed power lines, tree limbs, and general blockages in the road. Never drive over a downed line with your car. If the car has made contact, your car could become energized. Stay in your car and roll your window down to call for help. You can also use a cell phone to dial 911.

"... If the car has made contact and catches on fire, you have two problems. Don’t panic! You must get out of the car in this instance. The way you exit the car will determine whether you live to tell about it. Open the car’s door and stand on the floorboard of the car. Jump away from the vehicle with both feet together as far as possible. Don’t hang on to any part of the car during the jump, including the door handle. If you do, you’ll likely become the path to ground from the energized car to the street below. Remember, your car has four rubber wheels and is essentially insulated from the ground. When you just step out out the vehicle while touching it, you have completed the circuit.

"De-energized Power Lines - Although you can see that the power lines are down and the power is out, don’t think that it is safe to move a downed line. These power lines could become re-energized at any time! Never assume anything when working around power lines. Instead, assume that they are live and that electrocution dangers exist."
From 'Downed Power Lines'

Sue

I agree with Susan, there is no way that I would ever assume they were not live. A couple winters back one went down on the rural road I live on right in front of my place, I called 911 as it was obviously live and the fire department blocked the road until a crew got out here from the power company. I would think if the power company had already been there the lines wouldn't be on the road. Those things are nothing to mess with.

Downed power lines? That's serious business.

If you could visualize the amount of energy in a power line as a fire, you wouldn't even think about driving through it.

A tree took out the 15kV lines to my parents' place a couple of years ago. Even though they were both lying in a trout pond (the perfect earth ground, and no dead/boiled fish in evidence), I was not inclined to get close.

There are ways to detect voltage without contact, but in this scenario you could easily become part of the circuit before you could do the measurement. You can't help someone in distress by adding to the casualty count.

EDIT: To be fair, if I knew the line in question with a high degree of certainty, and had reliable evidence that it was de-energized, I might cross it if I had no other choice. An interruption in the overhead supply line past my house, for example, would be pretty obvious; the neighbours' yard lights would all be off. But in many other places, the line does not feed local residences directly, or at all.

Generally, above 7.5 KV, the tires last about 30 seconds. The next step following to four loud " POP's " is dark black smoke from your tires and you corpse.


We once had a lineman make unintended contact with 30KVa. He lost track of the lines and hit one with the arm of his aerial lift truck. It was not enough of a short to ground to cause the circuit breakers in the substation to trip, so he rode the lightning until the local utility dropped the power.

By that time he and the truck had completely burned to ash.

Keep in mind, within 4 feet of typical electrical transmission lines, the power can and will jump to the best path to ground.

DO NOT SCREW WITH DOWNED LINES.

Knowing the downed lines might be live or become live at any time, it would take a rapidly approaching and imminent threat of death to force a conservative, survival type to choose a close encounter with them. But what if there was such threat of death? How then would you proceed?

If the Ground is Wet,Where the line/s have fallen,Stay Far away from it,Period!If someone is Stranded Between Powerlines,& Power co. or Help is 4hrs.Away or something like that,Lots of Dirt, Shoveled over a Line with Planks on Top,Would probably suffice, for a Rescue of The Stranded Person, But Only if it isn't raining/snowing!Note:There are Seperation Switchs to cut power on Power Lines,Usually Located on Power poles,& Usually 10-15' High,& Locked as well,But It could be done,If you cut the lock! This would work for an Imminent Threat Scenario! The Big Huge Metal Towers with The High Voltage Lines,I don't have a Clue,Short of a helo-lift!

With all respect, I have major problems with this advice.

For 220V yard wiring, it would work. But with live wires in the kilovolt range, all sorts of materials that would normally be insulators become conductors. This includes dry wood and soil.

Dry wood/soil ARE Not Conductors for Any Voltage,However with The Mega-Amps Powering Kilovolt lines,They aren't much of an Insulator,In that regard,That's For Sure!You Excluded what I had to say,Below that!Also It's Not Advice,It's a Suggestion for A Haste Scenario,ie. What is Immediately at Hand to Help.Either you Help,or You stand there doing Nothing,Your Choice!

A couple of things. In an urban area with a lot of trees, you could become boxed in with downed lines.

In a serious region wide storm, I could imagine help could be several days away.

Second, there are induction testers for home voltages, I can't imagine it wouldn't be possible to detect without actually touching the line.

What are the procedures used by linemen? It seems to me the would double check lines before working on them -- and possible safety measures like grounding to earth.

What are the real working parameters for safety? Is there a possibility of arcing, or is avoiding direct contact adequite?

Are the lines insulated, or no?

-john

I didn't get many other pictures this day as I was too busy with what I was doing, but there were a LOT of downed trees and power lines this day. And, I think it easily could have been worse.

Urban + trees + wind = lots of downed power lines.


Dec. 15, 2006 wind storm, Bellevue, WA

If I really needed to know the answer, I'd get a limb or pole, get it real wet, stand it vertically where it would reach the line, and let the drop across the line. If no obvious power evident, then get a cat or some such to drop in the water puddle. Just kidding.

After witnessing a high voltage line on the ground, I can tell you for certain that you wouldn't want to be testing it with a home voltage tester. Much more juice than your home system.

When that line went down a couple of years ago on the road in front of my place it was frightening (loud pops and flames) as it kept arcing then it would die down and then arc again. They had two fire trucks down here and the firefighters were not about to get near it, they just sat with their emergency lights on and waited for the power company. When it wasn’t arcing one wouldn’t have been able to tell if it was live or not. Things like this are why we prepare to stay put in our homes or vehicles. I can't think of a scenario where I'd attempt to cross one.

Don't even go remotely near a downed power line. According to the source below, the voltage may be so high with a downed power line that a person can become a victim of electric shock without even coming into contact with the line. The source even recommends RUNNING away because by running you'll only make contact with the ground at one spot at a time, and so the current that is in the ground will (hopefully) not flow across your body via both legs.

http://www.allaboutcircuits.com/vol_1/chpt_3/7.html

I'd treat downed power lines like tornadoes and go the opposite way.

Seriously?!? It's a survival site here. So here's the surivival tip: don't freaking touch them. If someone's near them, oh well. Sorry charlie. Good luck. I'll collect your corpse later. No point adding to the body count. Yes, it's harsh. But rescuer safety is priority 1. If you're "boxed in" then either A) stay inside the box, or B) you'll be that guy I just wrote about.

I've always heard live power lines spark/snake across the ground.
All I know is every downed line I saw at work, we waited a couple poles away, called dispatch with the pole number (where we were, not the downed one!), and waited til the power/phone company came out and THEIR guy touched the lines to prove them safe.

But, to answer the OP's line, sure there's a way to tell if it's a live line. Have something living touch it. If that living object dies, it's a live wire.

Seriously?!? Nobody said anything about touching anything. Nobody said anything about taking risks for kicks.

I was hoping to gather some *information*, but... well...

-john

OK,Let's Make a Quick Scenario,Shall We? Your Pregnant Wife & 3yr.old Daughter are Trapped,Between Downed Powerlines,Professional Help is 4 hrs. away,The sky is Cloudy,& The air smells of Rain,coming soon,Will you still say"Sorry Charlie"? I Think Not!

Go the other way / don't try it is the only good / survivable approach for the untrained. On the other hand this is equipped to survive and equipment does exist to help properly trained people evaluate the hazard level and respond. Just keep in mind that even properly trained and equipped people can and do die in situations like this.

Any active power line (in the USA) will be carrying 60Hz power and generating a detectable electrical field. There are sensors that can detect these fields from a relatively safe distance. This isn't the little $50 AC detector you get from your favorite HW store but purpose build devices for EMS and Electrical workers. Typical prices are in the $300 and up range and the sizes are not really good for EDC.

The biggest problem with these detectors is that they cannot tell you when the circuit will re-energize and if you are too close when that happens survival is highly unlikely.

- Eric

Depending on the voltages involved any direct action on your part is unlikely to help and is very likely to cause them significant distress. Without the right tools, training and a correct understanding of the voltages involved waiting is probably the best approach. Hard call to make, but adding to the list of victims (and going first) isn't helping anyone.

When working with high voltages there is no such thing as an "insulator", there are just various quality levels of conductors. Electricity is lazy and will follow the path of least resistance. You never want to be in that path and distance is the best way to stay safe. Proper equipment and and training lets you work in areas with higher gradients (closer to the source).

Keeping this in mind, look at how high the poles are and how far apart they are. Ideally any thing you would do to "help" would need to be done from a distance of at least twice the pole height or separation distance from the downed lines. Around here that would mean you need to stay at least 60 to 90 feet away from the problem and you should be much further for higher voltage lines. What can you do from this distance? Best choice - call 911 and or/the power company.

After that there are no good choices. For the scenario you describe and assuming wooden power poles (single pole), I might try killing the power lines around my family by taking down some of the poles feeding the downed lines. This isn't a great idea but desperate people do silly things. Not sure how I'd accomplish this before help arrived without a great chainsaw and lots of spare chains (creosote kills chains very quickly). If the "poles" are metal or three legged I think I'd spend my time between phone calls consulting a much higher power and trying to keep my loved ones calm.

Sometimes there really are no win scenarios.

- Eric

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

OK,Once Again! My Choice for this Matter,Would be to Secure the Cut End of the cable with Timbers or 4x4's or 2x4's or Plywood,but Definitely Not particleboard as,It has metal Fibers.Then Shovel Dirt onto the cable,Behind the Secured end,When I feel there is enough Dirt on said cable,I will Jump over it,& Guide Whoever is Trapped,Back to the Secured Point,& Have them Jump/Leap over to Safety,Jump back over Myself,& Secure/Tape/Rope off the Area!The Main Point is to Secure the Cut end of the Cable,to Keep It/Them, from Whipping Around!This Is Something,I,Would Choose To Do,IF...Professional Expertise,Were Not Available! Intestinal Fortitude is Required for Much Greater Purposes,Than The above! That said,Some have it,& Some Don't!

This isn't about intestinal fortitude, it is simple physics and the unforgiving nature of high energy systems of any type.

The things you don't and can't know (how much moisture is in the wood/soil, how many volts is the line, are there any holes in my shoes/gloves, or when will the power come back on) are what will kill you. Even highly trained professionals die when working with high power levels.

Assuming you decide intestinal fortitude is the answer, I hope you know what voltage level the line is at before you start throwing wood and dirt around.

For a local (i.e. low voltage) distribution line you might be ok if you can find a nice dry 2x4 or 4x4 (at least 8' long) and the ground conditions are also nice and dry. I'd still give it a good toss from a fair distance away just to be sure.

For higher power lines I hope you feel up to tossing around some pretty hefty hunks of wood and moving a whole lot of dirt. In dry conditions, using nice kiln dried lumber (no preservatives or glues of any kind), you would want to be at least 15-20 feet away from where the line is "grounding out" if it is in the 115KV range. That sucker is also probably snapping and jumping like a mad thing, either from arcing or the wind that brought it down.

None of the above lumber is in my BOB, EDC or backpack. Usually not in my SUV or home either. I don't often carry a full size shovel along either, much less a backhoe. Going with what I can find/cut, dig up with what is on me, I suspect the pro's will be at it before I can accomplish anything short of killing my self and making a very bad situation even worse for those who get to watch my untimely demise.

With all of that out of the way there are a couple of scenarios where I would be willing to give it a go, but I'd be going in to it knowing full well that I would probably die trying. It would be risky, stupid, and absolutely the wrong thing to do but what can I say - parents aren't very rationale when the kids are in danger.

-Eric

Parents aren't very Rational,when the kid's are in danger!It is EXACTLY,Intestinal Fortitude,For a Very Short amount of Time!Was There ANYTHING that I wrote that tipped you off,that I would Do this For The heck of It?I'm Not the Type of person that is going to Stand there & Do Nothing! Rational or Irrational,Something MUST be Done,when All other Recourse,has been Exhausted!Of Course I Know What Voltage is in the Line,Don't You?

Sometimes the best thing to do, is nothing. Having a second victim does not help the primary victim and will only complicate the situation for rescuers who do have the knowledge and tools to reduce the risk of rescue. Even rescuers make the fatal mistake having the “intestinal fortitude” or what is more appropriately called tunnel vision or lack of situational awareness and feel they have to do something. Most of these rescuers become victims; it is common occurrence in confined space and trench collapse rescues. The first arriving individuals/units feel helpless, enter the hot zone and become secondary victims, unfortunately often with fatal results. Sometimes it takes real intestinal fortitude to do nothing, until the risk(s) can be mitigated.

Pete

If it isn't obvious from previous posts, I fully agree with paramedicpete. By my definition, Intestinal Fortitude is doing the right thing, no matter how hard it is. With power lines (or any other situation you are not prepared / trained for) that often means waiting for those who do have the right training and tools. Good intentions mean squat if you make things worse by adding to the body count.

I am also self aware enough to know that my kids are my weak point and I am not sure I would have the courage to wait despite my theoretical understanding of the dangers involved.

- Eric

First rule of First aid:- prevent yourself becoming a casualty, or words to that effect.

Having just had a friend of mine used as a path to ground after he went to climb on a crane that had wrapped itself up in an overhead line at night and seen the hole it left, you wont find me going anywhere near downed or cut lines.

In short, NO. Not without specialized gear and training. ALL down lines are to be considered deadly until the power utility confirms otherwise. End of story.

One other thing - Step Potential.

You don't even have to step ON the line - just NEAR it and your salty body becomes a better path - through your forward foot, and back through your trailing foot.

Boom.

All you need to see:
http://www.youtube.com/watch?v=eYUmdqQ94Ao

Here are a few more videos of high power in action:

http://www.youtube.com/watch?v=BtQtRGI0F2Q&feature=related
http://www.youtube.com/watch?v=PXiOQCRiSp0&feature=related
http://www.youtube.com/watch?v=-Q7qATVBEW8&feature=related
http://www.youtube.com/watch?v=q1wsAd9q_4w&feature=related

Is there a way to give the electricity another path to ground that could create some kind of safe zone? [And, yes, I have no real idea what I am talking about.]

Guns are always loaded, downed lines are always live.

This isn't knife-in-a-toaster voltage that you have to touch to get shocked. High voltage is 'controlled lightning' that will jump a surprising distance to get to you.

Stay away!

No one wants to encounter a downed power line. Because it is a real world possibility, exploring options for dealing with the situation fits with a survival forum. Creativity in questioning currently accepted wisdom is one possible path to a better understanding of the world and better surviving in it.

Maybe there will never, in the history of the world, a better strategy for civilians dealing with downed power lines than "stay away." But, one, you never know until you ask, and two, given the history of scientific progress, I doubt it.

Actually other than the line to my house from the pole the answer is no I don't know and unless you work for the local power company (or maybe EMS) you probably won't know either.

From the pole to my old house (most houses in the US actually) was 220VAC with some really high current limit (like way way north of 200 Amps). If that one comes down (or if several in your neighborhood come down) tension tends to pull it back to the pole and getting boxed/trapped is unlikely (and yes sometimes luck just plain runs out).

I am pretty sure my old neighborhood had 440ish VAC lines feeding the on the pole transformers (old neighborhood) but I think the underground line feeding my current neighborhood is around 600V but I don't know for certain in either case.

Most of the above ground lines around here are either local distribution (something around 600VAC) or transmission lines (more than 1 KVAC, usually over 100KVA). Getting these two lines mixed up is a sure way to cook yourself even if you equipped and prepared to deal with the lower voltage.

-Eric

Here's the only strategy that I know of.

1. Get trained as a linesman for a power utility.
2. Obtain, and maintain, the needed equipment at all times. This includes things like a 30' "hot stick" a bucket truck with an insulated boom, rubber gloves and bibs, remote voltage sensors and breaker manipulating tools.
3. Be ready and able to use these tools at any time.

Look, I know there's all sorts of Walter Mitty adventures we go through in our heads, and I know "run away" isn't always a strategy anyone wants to hear, but in real life that's often the best thing to do.

Let me put this to you another way.

Look at this video:

http://www.youtube.com/watch?v=qAHRWeQhz3c

The line is likely STILL LIVE after the boom! You saw what it can do...those folks were a little too close, but at least they stay back.

Graphic: http://www.youtube.com/watch?v=26Y-axZqMAI

This thread makes me grumpy. As before, I get the whole "stay away" and the high risk aspect.

And I never said anything about manipulating or touching the lines.

So far, about the only useful thing I've seen in this thread is Eric's comments about voltage differential, and "the shuffle" (although it would be interesting if someone could post some insight into at what point the path between leg#1 and leg#2 becomes a more desirable path than the ground, etc.)

My original inquiry was about detecting if lines were live or not, not because I was going to run out and attempt to stick my tongue on them to show how wily I am, but rather because I've seen first hand when you mix trees and wind and urban areas, that you can find yourself in a maze of downed lines and you never know what is going to happen that might cause you to need to leave the area.

Clearly the best option is to avoid or wait. But, as Dweste points out a couple of posts above, it seems like a reasonable topic of discussion.

I cannot believe it is not possible to detect the voltages remotely or semi-remotely. I'm sure linesmen must do this, I can't imagine they don't double check before they approach a line. So what and how do they use? [Yes, I get that they could be re-energized w/o warning.]

Information about the types and methods of lines and how to identify them would be useful. I really doubt the lines on a residential street are 115KV for example.

Basically, can we stow the condescending attitude and share some information and logical discussion?

If I ever turn up dead, killed by a power line, I promise I won't hold you accountable. At least for any information you *did* provide. :-)

-john

and you don't even have to mix them up. Just because its supposed to be lower voltage, doesn't mean it will remain lower voltage when its broken; resistors fail, lines get crossed, sewer pipes get electrified ...

Lets see, on the one hand, becoming a lineman
http://www.lineman.edu/assets/content/docs/enrollment-CA-2010.pdf
* four concurrent months (15 weeks) of full-time enrollment
* TOTAL FEES & TuiTiON .... $10,100.00
* CLImBING & HANd TOOLS .... $2,218.00
* TOTAL COSTS .............. $12,382.00
* state certification exam...
* four year apprenticeship before you're qualified to be in charge (always work in teams)


on the other hand, running away is free , and you're instantly qualified

Thanks. Avoiding them didn't occur to me.

-john

I Believe I, Owe You an Apology! It was on Your Thread,That I started the hyperbole,By Answering a Question from Someone other, than Yourself! Kinda' funny though,It sure did stir up a Big pot of Emotional Paranoia,with a few slices of Uboob,thrown in the pot!One thing for Certain,We Now Know who would have NOT, Have Been good Friends of Benjamin Franklins,LOL!

No worries, I guess this thread was destined to go this direction no matter what.

BTW, good tip about the cut off switch. I'll have to keep an eye out or them.

Thanks,

-john

John,

I don't think anyone is intentionally being difficult on this topic, just advocating the surest strategy and tactics for dealing with a very high risk scenario. High energy systems of any type should be approached with utmost paranoia. High pressure steam, high energy turbines, even lightning are things to be very very careful around.

Tools and techniques do exist for working with live high voltage power systems. As pointed out in another post the training is expensive, extensive and I'll add not a guarantee that you will survive the job. The tools are also expensive and require regular inspection/certification to be "trusted". Several sensors are available for EMS and trained Line workers. Try looking up "lineman tools" or "Hot Sticks" or "non contact voltage detector" in your favorite search engine. I think that name brands and certification to applicable standards would be critical things to consider. Keep in mind, these are tools for trained experts, not a DIY project.

My understanding (limited) is that there are relatively reliable non-contact voltage detectors that can be used by electrical workers. The challenges with these are that they are subject to interference from various sources (including automotive ignition systems) and while they are non-contact they need to be in relatively close (within a few inches or feet) to the voltage source. This is usually closer than you would want to approach a downed line. For professionals this is less of a problem because they have the other tools/equipment/procedures for getting the sensor in close without undue risk. These sensors are also usually considered backup systems, not primary.

With most high power systems (electrical, RF, mechanical) the best safety assurances for those involved is iron clad processes and procedures, including two person checks on everything. In the scenario being discussed that is not an option so nearly all of the safety "margin" has been eliminated. At this point most trained lineworkers will stay away unless they are part of a team working together to manage the problem.

The step voltage differential that both Martin and I mention is one of many things to be aware of and I brought it up to make a point. I'll emphasize the point here - If you have on "typical" footwear near a distribution line that is shorting to ground your foot/shoe could be the best path to ground (or at least a lower potential level). In the example I provided the surface voltage difference from your toes to your heel would be over 300VAC and essentially unlimited Amps. At that potential level, arcs through your foot are not just possible but likely. The example also assumed a solid grounding into soil (not an arcing, jumping line) so other parts of you may become part of the circuit (via air/plasma arcs) if the line is not actually grounded into the soil. Shuffling only really helps at lower potential gradients (i.e. farther away from the ground contact point or a lower voltage source).

I will keep trying to answer / research questions that are brought up in this discussion but I sincerely hope the information I provide brings anyone reading this thread to the recognition that Stay Away is the only survivable alternative for those of us who do not have the proper training.

For reference I have a degree in Electrical Engineering and I do not work in the electrical power industry.

If I did offend (and I hope i didn't) then I am sorry. Please remember that when some of us answer we are also answering it with the thoughts that SOMEONE out there (usually a nonregistered guest just 'peeking' at things) will take what we say as ABSOLUTE FACT even if we clearly state it is our OPINION! Please remember that as is in this case....I am CERTAIN there are ways to check the line.... BUT I know I don't know specifically so I will advocate the SAFEST way to approach the situation (don't even think of checking) so that the most causual observer will think---I'd be insane for even thinking it! Personally I do think it is an excellent topic. I am interested in the answers. Don't know if I'd try any unless I had ABSOLUTELY NO OTHER WAY....I've seen the damage done by them first hand.

Aside from all the problems of determining if the lines are powered now, there is the fact that they may become powered in an instant with no notice.

Scenario: you need to cross the downed line. You check and are sure the line is dead. You take a couple of steps and are near the line when somewhere someone throws a switch or something else happens and the lines are now instantly powered and deadly.

Please, treat all downed lines as live at all times just like you treat all guns as loaded.

There are lots of self resetting circuit breakers out there for critical circuits, where the line can go dead and come back on after a set delay.

You can buy the testing tools at any electrical supply house if you really want to. I've seen them in use, just point the stick toward the line in question and it lights up if its powered (inductive amplifier). Those tools are not cheap since a false readng will carry a high price so they are quality made and the companies making them have high insurance.

<sarcasm>I suppose that means we shouldn't learn anything about firearms, either.</sarcasm>

-john

To answer the original question of "How can I tell?". The answer is, you can't, and that is precisely why everyone tells everyone to treat them as live, and to stay back.

See this video: http://www.youtube.com/watch?v=kVXi_0H_ZzM

This video shows a tree being blown into power lines, and it illustrates a couple of things:

1. The lines remain energized long enough to burn the tree. A current is being applied between two points, and no effect on power transmission. This is probably happening between the two sets of power lines (the high and medium ones shown in the video). In other words: The system does not detect the problem.

2. Once the line shorts (about the 4:00 mark), automatic breakers trip shutting off power. This is what you would expect, right? Then, what you would not expect (but has been mentioned here) is the additional shorting. That is the system attempting to clear the obstruction and returning the system to normal. Useful for clearing squirrels and other small animals. This is an AUTOMATED response to the transient power issue and is NOT initiated by a human.

Rules of thumb (yes, already mentioned):
- Treat all WIRES as live (regardless if they are telephone, cable, or insulated)
- Stay back at least 3 poles away from a downed pole. Tension in the lines could cause a cascading failure of the poles down from the broken pole.

Please watch the following electrical system safety video: http://www.youtube.com/watch?v=7VXEb3_apOc ( ~20 minutes long - geared towards construction workers below supervisor level. Does contain good information on emergency info.)

This video shows the conductive nature of a steel-belted radial tire:

http://www.youtube.com/watch?v=UqcK2t6eWrs

The design of modern electrical systems and liability issues, no one will tell you how to really tell a line is dead. Pretty much comes down to a human telling another human "I shut off the power to that line by a physical mean".

I have a feeling that the people who keep trying to figure out how to get close to live power lines are not looking at the videos. Please see the explosion at 4:01. Then, imagine the tree is you. That's what happens if you get electrocuted with that amount current.

So, here's another answer to the original question. From a safe distance, find some macho dude in the area who knows everything and has a need to impress people. Inform him that he absolutely should NOT go near the downed power lines because they're a great risk to his life. Being the type of guy he is, he'll figure out somehow if the line is live or not...

OMG! My head is hurting. It looks like we're going to be planning a couple of memorials, gang.

Nope, quite the opposite.

Treating all guns as loaded should be common sense since the gun in question (per the quote) is in your control and you are responsible for the potentially destructive results. This means you should be very familiar with this tool that you control.

The downed power line is every bit as potentially destructive but the power is not in your control and is probably under some automatic control that includes cycled resets. With downed power lines all you control is your actions.

Maybe it would help to think of the downed power line as an firearm that someone is pointing at you ? At that point I am going to assume it is loaded no matter what the ill considered person on the other end says.

- Eric

Sorry, I figured the sarcasm would be self evident.

Despite considering all firearms loaded, we still can talk about how they work, and by understanding the danger and how they function allows us to deal with them if we come across them.

Despite having a firearm pointed at you there is plenty of reasonable discussion of doing something other than just complying (probably the closest analogy to waiting it out).

In any case, I regret starting this thread. Sesh.

-john (the obviously stupid and careless, walking casualty)

Don't be discouraged, your thread was useful and interesting. Riling some folks up should not stop creative thinking and questioning - indeed it just demonstrates the need for more intellectual tolerance and reasoned debate.

So, post on!

Sorry about missing the sarcasm. Odd that, I tend toward excessive sarcasm most of the time. Similarly, I am sorry to add to your frustrations.

I have been trying to provide information for consideration and discussion, while also including what I thought were appropriate cautionary statements. Personally I find the need for the cautionary statements a royal pain since most of the people visiting this forum are what I would consider reasonable people. Unfortunately it only takes one "unreasonable" person to ruin a good thing so on this particular topic I have probably been erring on the side of paranoia and excessive CYA verbiage.

-Eric

PS - I never said I would comply if someone was waving around a gun, just that I would assume it was loaded. But that is completely off this topic

After reading all this again, I had a scary thought:

If power lines fall on your car, catch the car on fire, and its icy out, you're pretty much screwed ( I think... ).

Not exactly sure how you will be able to jump away from the car and land safely and then hop.

Any ideas?

I was thinking of this thread when I read of a tragedy killing three people when a power line came down in their backyard. Victim #1 approached the line, tried to step over it - Zap. Victim #2 came to his aid - Zap. Victim #3 also came to render assistance - ZAP.

I cannot find the URL for the life of me or I would post it...

To get to your question, I might try to extinguish the fire first, although that could easily not work. Otherwise, choose a location where you can achieve maximum distance. I believe it is best if you can land on one foot. Wear rubber soled foot gear-it will help a little.

http://www.redlandsdailyfacts.com/news/ci_17153942

Here's another link, along with a different incident where three people were electrocuted:

http://latimesblogs.latimes.com/lanow/2011/01/3-electrocuted-in-backyard-of-san-bernardino-home.html

http://www.livevideo.com/video/093FDF0DDD964E229220F22930B4B10E/three-people-on-a-pole-get-ele.aspx

That second link is really startling and very impressive ( I almost said electrifying, but I decided not to).