Van vs Downed Power Lines

[rdale]

June 7th in Delta Township, I went out with some family to look at post-wind storm damage. When we got to Grand Ledge, I started down M-100 but stopped and turned back because it didn't look as bad.

Just after getting back to Saginaw Hwy, GL had a call for a van on fire from driving over power lines. We went back down and since I was already getting storm damage video, I kept the camera rolling. I've never heard of a car catching fire from rolling over lines...

http://rdale.bholcomb.com/carfire/carfire.html

Couple of good explosions, especially around 1:25 into the video.

- Rob

 

[Bill Schintler]

RE: Vehicles and downed lines

While chasing, we occasionally encounter areas with storm damage. I've said it before in another thread, and I'll repeat here: Never drive over downed lines - they usually are not live, but you can never assume so. Never drive under damaged lines. If your vehicle rooftop antenna comes into contact with a line carrying 15,000 volts or more, the results could be very bad for your health (not to mention any equipment on board). Lastly, if your vehicle does come into contact with a line, NEVER exit the vehicle.
- bill

 

[David Drummond]

I've driven over lines across the pavement hundreds of times with nothing happening. Assuming they are laying FLAT on the pavement. If those lines are still live, I guarantee you will know it if they are touching the ground because they put on one hell of a fireworks show. I wouldn't get out and touch them, but I don't mind driving over flat lines with rubber tires. Of course that's just one or two lines. I guess if there was a whole bunch of them I probably wouldn't.

On the other hand I am very careful about getting under anything I think the antennas would touch, because if they are up in the air, they probably are still live and haven't tripped the line breakers like the one's on the ground will eventually and the fireworks stop.

BTW, this is what they look like when they are still live: http://www.youtube.com/watch?v=xLlOjWmFaS4&feature=related
Every live line touching the ground I ever saw does that, and creates some cool glass beads in the dirt.
Never saw a dead one do anything but lay there.

 

[rdale]

This guy didn't mind driving over them either - and it turned out bad... Not sure why. Looks like he was pulling into his driveway, they must have been laying off the side of the road.

 

[David Drummond]

Are you sure your information on the story is good Rob? Maybe they were hanging and still live. In all my years of chasing and the years on the fire dept running down power lines called in, not once EVER have I seen one laying on the ground that was live and it wasn't obvious. When that much electricity grounds out, it welds.

 

[rdale]

That's a possibility... I'll be seeing the chief later this week to give him the full video, I'll check.

 

[Bill Schintler]

Are you sure your information on the story is good Rob? Maybe they were hanging and still live. In all my years of chasing and the years on the fire dept running down power lines called in, not once EVER have I seen one laying on the ground that was live and it wasn't obvious. When that much electricity grounds out, it welds.

True, if they're live it's almost always obvious - they'll be arcing and sparking if they're on the ground or trees. What you have to remember is that circuit breakers may automatically re close the damaged circuit in an attempt to clear the fault (many non-storm related faults are due to such things as birds and rodents making temporary contact). So, without warning the downed line may become live for a moment or two until the breaker senses the fault and reopens. I work with high-voltage and high-energy circuits so I have a lot of respect for that stuff - bill

 

[Jerry Prsha]

Educate me on something. If a car is struck by lightning, the charge jumps from the body to the wheels and arcs to the ground; thereby not affecting the tires.

Why would driving over power lines cause an issue, even if live?

I can understand not parking on on live wires because I would think that the heat alone could catch rubber on fire. I just don't see the power leaping into the car and causing issues for the short time you're traveling over them. The electricity is going into the ground and has no reason to take the toughest path jumping the tires to the hub and axle again.

Hmmm....

 

[HAltschule]

I have been a firefighter a fire investigator for nearly 19 years and have never heard of a vehicle passing over live power lines and catching fire. I can almost guarantee that they were dangling and electrified the vehicle. That said....those firemen were crazy to extinguish the fire. If there is no life or structure threat you are supposed to let downed powerlnes burn whatver they are burning until they are no longer dangerous. I wondeer if the even knew that live powerline were down there? I saw an obvious blue arch at one point in the video so i knew they were there. The explosions were the tires going kaboom. Interesting scenario.

 

[David Drummond]

Educate me on something. If a car is struck by lightning, the charge jumps from the body to the wheels and arcs to the ground; thereby not affecting the tires.

Why would driving over power lines cause an issue, even if live?

I can understand not parking on on live wires because I would think that the heat alone could catch rubber on fire. I just don't see the power leaping into the car and causing issues for the short time you're traveling over them. The electricity is going into the ground and has no reason to take the toughest path jumping the tires to the hub and axle again.

Hmmm....

Just as a side note, I have see a couple of times tires blow "out", as in from the inside out, where lightning jumped from the rim to the ground through the tire.

 

[David Drummond]

I have been a firefighter a fire investigator for nearly 19 years and have never heard of a vehicle passing over live power lines and catching fire. I can almost guarantee that they were dangling and electrified the vehicle. That said....those firemen were crazy to extinguish the fire. If there is no life or structure threat you are supposed to let downed powerlnes burn whatver they are burning until they are no longer dangerous. I wondeer if the even knew that live powerline were down there? I saw an obvious blue arch at one point in the video so i knew they were there. The explosions were the tires going kaboom. Interesting scenario.

It was the same way with us on the FD. If there were lines sparking, it was blocked off a good distance away until the electric company came and shut it off. Usually they would jump around for a while sparking and eventually the circuits blew and they were dead. Sometimes if it was attached to a transformer it would blow up and they would go dead.

The wind in west Texas blows the lines down a lot. I sat many an hour in fire vehicles blocking a road or something waiting for the electric company to show up. Although I guess it's possible, not once did I ever see one re-energize after it went dead.

This of course is one of those personal safety alarm issues that I while I do it, I wouldn't tell anyone else they should do it. I just have no problem with it, given my FD experience with them and being able to tell if they are dead or not. I certainly don't lolligag around them. If I have to get over them, I do it quick and get away from them.

 

[rdale]

they even knew that live powerline were down there?

Yes - they didn't do anything until the power company pulled in.

I saw an obvious blue arch at one point in the video

That was the airbags (I assume) blowing - it came from the engine compartment and it was an explosion of some sort of chemical.

 

[Bill Schintler]

I can understand not parking on on live wires because I would think that the heat alone could catch rubber on fire. I just don't see the power leaping into the car and causing issues for the short time you're traveling over them. The electricity is going into the ground and has no reason to take the toughest path jumping the tires to the hub and axle again.

Not meaning to beat this into the ground, but I think my previous post left a question or two. Everything you say is true - in a worst case scenario, continual arcing from a (stationary) vehicle to ground could cause the tires to ignite. In my last post, I should have made it clear that one would normally be safe to drive over downed lines while remaining inside the vehicle - Although I'd never drive over "obviously live" lines that are arcing and sparking in any situation. The major risk is if one steps out of the (potentially "hot") vehicle, and onto the ground while at vehicle potential. In the unlikely event you MUST exit a potentially live vehicle for any reason, jump out of it such that you do not simultaneously contact the vehicle body and the ground.

Regarding contact with overhead lines, or a lightning strike for that matter, the conductive body of the (hard top) vehicle normally acts as a Faraday cage, and the current travels through the body of the vehicle and around the occupants. An exception to this would be a situation where a rooftop antenna contacts a live line, and the currents may be conducted into the vehicle via antenna coaxes (again, a worse-case scenario).

- bill

 

[Jason Foster]

Another van on fire....wierd

Watching another vehicle on fire is wierd now, since my burned up a little over a month ago. I wish I had such good video of mine.

The explosions are usually from the tires blowing out. Some of you firefigher guys might tell us if you've ever encountered a vehicle exploding from gasoline. Seems like all the car fires I've ever seen, it's just the tires exploding.

Van Fire thread:
http://www.stormtrack.org/forum/showthread.php?t=16667

 

[Jerry Prsha]

Just as a side note, I have see a couple of times tires blow "out", as in from the inside out, where lightning jumped from the rim to the ground through the tire.

David, I've heard that too. But I guess my point is, lighting is several millon volts... some say as high as 300 million. I can see something like that causing incredible damage.

But a downed/grounded power line isn't near the stature of lightning and has no path to travel up into a vehicle.

I'm not saying that anyone that says not to drive over them is wrong... I just can't get my head around why this would cause a problem, at least logically.

I think this is a problem that the "Myth Busters" TV Show should tackle...