Hi Tech Hi Tension Maintenance

[JRobyn]

Hi folks,

Maybe this doesn't fit in the Safety forum, but where else?

Heard choppers very low behind my house this morning and went to look (with the camera) and saw this. Amazing! Both pilot and lineman must have nerves with more steel than those towers. These are 500kv lines. Wonder if OSHA approves?

- Jay

 

[shvl73]

I saw a tv show on that, may have been discovery channel. You'd really have to trust your pilot.

 

[MrJimi]

I've seen a good video on this and it's very interesting to watch here
Power line cleaning

 

[tomd999]

Hiya,

I have a buddy that does that. He gets paid very well come to think of it. They wear a chain suit so the electricity goes around them, and are only able to do the live attach in very specific conditions. Yes, he has some gruesome stories about "safety mishaps".

I'll stick with 12v

Tom

 

[DieselPower]

It's just like birds that set on wires. You can't get shocked if there's no ground. I saw a show on TV about that also a year or two ago. The one I saw actually had the guy suspended under the chopper on a cable. The main problem was the static discharge from the chopper when they first make contact with the wire. The wire dog makes contact with a grounding rod first and then can make safe contact with the live wires.

 

[N80]

Yes, but the other line will serve as a ground and a helicopter easily spans both lines.

 

[jsborn]

It's just like birds that set on wires. You can't get shocked if there's no ground. I saw a show on TV about that also a year or two ago. The one I saw actually had the guy suspended under the chopper on a cable. The main problem was the static discharge from the chopper when they first make contact with the wire. The wire dog makes contact with a grounding rod first and then can make safe contact with the live wires.

The line he is working on in the pictures is the static wire it is not energized but does have a lot of static in it.

DP you are kinda right but birds can't sit on conductors energized at 500KV or even 230KV. The EM field surrounding the conductors will smoke them if they try. That along with potential diff in the body is why we wear the chain male suits. they are really carbon woven fabric that allows us to enter the field while the difference in potential across our bodies is equalized by the low resistance conductors in the fiber.

Without going through a lot of math lets just say the resistance from one side of your hand to the other is small enough at these voltages to cause large currents to flow through you with out the protective suits. This current flow is also called cooking which is not a good thing to living things.

I have been energized at 500kv a few times and it does give you a strange feeling and make you glad to be back on the ground.

 

[horse7]

....
DP you are kinda right but birds can't sit on conductors energized at 500KV or even 230KV. The EM field surrounding the conductors will smoke them if they try. That along with potential diff in the body is why we wear the chain male suits. they are really carbon woven fabric that allows us to enter the field while the difference in potential across our bodies is equalized by the low resistance conductors in the fiber.

Without going through a lot of math lets just say the resistance from one side of your hand to the other is small enough at these voltages to cause large currents to flow through you with out the protective suits. This current flow is also called cooking which is not a good thing to living things.

I have been energized at 500kv a few times and it does give you a strange feeling and make you glad to be back on the ground.

Do you have any cites for frying birds at 230 or 500kv that were not involved in arc over? This doesn't seem plausible... I can see some field effects but not enough to cause that kind of damage unless the lines are tremendously lossy.

Many years ago I tried an experiment to find out what voltage was needed to fry flies (barns tend to have a never ending supply of the evil critters). This was using the bug zapper principle, arcing across electrodes. I found that around 300V the flies would be damaged but generally escape, at 500V they usually fried nicely (but dragged down the experimental electrodes so that usually others alighting would escape in the "damage" zone rather than "kill" zone) and at much higher than 500V they tended to veer off before landing. My theory was that the e field disrupted the wing operation or rotational sensor operation at higher voltages, causing the fly to coincedentally avoid the kill zone while staying away from the zone of problematic system operation.

Perhaps most birds are warned off very high tension wires by the side effects-- otherwise, birds being kinda bird brained, one would expect to have heaps of dead birds under 500KV lines with tree huggers howling like they do for the flying creatures diced up by windmills. Or maybe the birds are carbonized and no one misses them!

Perhaps I should toss a roadkill crow onto the nearby 125KV lines, see what happens

 

[jsborn]

Most of the dead ones are Buzzards and not many people even in California care about them. But you are probably correct they seem to be warned off as the try to land on the conductor but at 500kv the are warned about 20 feet away. The normal spacing for this class line is too much for a phase to phase flash due to wing span in most cases.

 

[N80]

The explanation on that History Channel show (for what its worth) said that the static kept them off the high tension lines.