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I have to admit, it was a fascinating video. The precision of the helicopter pilot is amazing. Just one wrong move though and both are dead. Surely there's a less risky way of doing this?

How did the lineworker and helicopter not get electrocuted? Is it because they attached themselves to the transmission line, similar to how a squirrel doesn't get electrocuted? Or were the lines taken down or something (I find that hard to believe but maybe). At those levels, if they were at the same voltage as the lines, isn't there still a risk of arcing to another line?

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The only way to do it with less risk would be to shut down the line, which would be tremendously expensive and might still result in more risk, since power outages can kill.

It doesn’t look like the safest job in the world, but a lot of crazy-looking things can be reduced to tolerable levels of risk with lots of training and good, methodical procedures.

After all, packing a couple hundred people into a pressurized tube six miles above the ground is pretty crazy too, and used to be fairly dangerous, but these days it’s the safest way to get from A to B.

AFAIK many crawler robots can place shunts on live lines automatically, without any risk. I wonder what's the advantage of doing it manually from a helicopter.

How do you get the robots onto the line, and how far can they travel? They might not be capable of handling a sudden problem in a remote area. Although I really don't know, as I just learned of their existence from your comment!

Those I know of are advertised as semi-autonomous and capable to move over any distance for days or weeks; the line provides both power and communications. Robots are put there in a traditional way, by line workers climbing the towers, then the operator controls them remotely if needed. Some models also appear to have a winch for the tools and spare parts if a problem is found.

I have no idea if they work as well as advertised though, hence the question.

I've seen those things crawling along a nearby power line a couple times, although these particular ones seemed too small to be able to do anything besides inspecting the line with a camera/sensors. I'm not in the US though, things are different here, we don't use aerial transport on every occasion.

EDIT: on a further inspection, the robots seem to have issues with crawling over more complex line sections, and are used mainly on very high voltage lines. Apparently, the tech is still in its infancy.

One pretty significant application 15 years ago of crawler robots (and the only one I've seen in person) was suspending optical fiber cables on the ground cables of VHV lines.

I saw a video where the lineman was actually left on the line by the pilot (hanging in some kind of rescue harness), then retrieved when the work was done. He could move along the line using it like a zipline. I guess it depends on the malfunction and the way it's solved; an overheated line connector is not something you want to touch or hang on.

Not sure what they do if the line to be fixed is not the one on the top (fixing one of the lower lines would mean the helicopter interferes with the upper lines).

https://www.youtube.com/watch?v=9YmFHAFYwmY

> There is only 3 things I have ever been afraid of; electricity, heights, and women. And I am married too.

There isn't a less risky way of doing this. This is actually safer because there is no contact with ground, removing the voltage potential (which is also why they make contact with the line, to keep the voltage potential as close to zero as possible).

Yes, most definitely. They still have to be careful about that. I expect it's an easy thing to avoid unless you're working on an inside conductor.

The whole thing is a conductor. Those lines are insulated only by air.

Edit: Misreading on my part. Parent meant "a line closer to the tower" not "a conductor within the line."

Pretty sure by "inside conductor" he means one of the lines closer to the tower. In the video I think he's working on the outermost conductor, i.e. the one furthest from the tower.

Ah, good point. Grandparent is correct. Carry on!

For conductors that the helicopter cannot safely hover close enough to for the line worker to work on from the helicopter, they sling load the worker below the helicopter, lower him down to the conductor he needs to work on, and he attaches himself to the conductor and detaches from the helicopter, and the helicopter moves away from the lines.

When the work is done, the above is reversed to extract the worker.

There's a segment showing this in "Modern Marvels" episode S11E45, "Wiring America" starting at 23:44 [1].

I've also seen a documentary somewhere [2] that was similar but more focused specifically on line work. That had a clip showing a worker being lowered to a particularly difficult to reach conductor. There were at least 3 horizontal layers of conductors, with at least 3 parallel conductors in each layers, and the one needing work was in the middle horizontally and had at last 2 layers above it.

For that one, they had several dry wooden poles connected end to end to form a kind of chain. They put this together in a dry area, then had a crew carry the pole chain outside careful to not let it touch the ground, so it would not get wet from the morning dew on the ground. One end was attached to the helicopter, which slowly started lifting it, with the crew that was holding it making sure to not release segments until they were sure they would not swing into the ground on the way up. Finally, the line worker was attached to the last segment. From then on, it was similar to the segment from Modern Marvels.

They used the dry wooden pole chain because there was no way to reach the work conductor without whatever was suspending the worker simultaneously touch two of the above conductors, so it was imperative that this not short out things.

I believe they used a pole chain rather than some non-conducting rope because a rope can get tangled in things or wrap around things. The pole chain consists of rigid segments, which are not going to get wrapped around anything.

[1] https://youtu.be/vuRNs50VMJ0?t=23m44s

[2] Probably on the History Channel or Discovery Channel.

The lineman (and my guess is the pilot too) wear a conducting and fire retardant suit made of metal threads. This essentially acts as a Faraday cage.

The lineworker and helicopter don't get electrocuted for the same reason that birds don't.

There is no way to ground (other than capacitance which likely causes the arcs you see in the video)

According to a comment elsehwere based on capacitance the amount of current flowing is rather low and not immediately dangerous.

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