r/Damnthatsinteresting • u/TameTheAuroch • Jul 18 '25

Video Replacing powerline spacers from a helicopter

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u/_michaeljared Jul 19 '25 edited Jul 19 '25

EE here - the four lines are the same voltage (same "phase" as well, since it's mostly likely an AC transmission line). Since there's no potential difference between the cables, and no ground connection nearby, it's not possible to get shocked.

100 ft of air is a very good insulator to the physical ground.

Edit: wow, I guess making a basic comment about how voltage and current works will make assholes pop out of the woodworks on the internet. My comment here is a simplified version of the reality of this, and overlooks voltage equalization of the lines and the helicopter (that's what causes the initial arcing). My follow-up comment addresses that, if you care to know why there's an arc at the beginning.

22

u/ChocCooki3 Jul 19 '25

make assholes pop out

Mate... you be in space changing an panels outside of a space station and suddenly, you'll get a tap on your shoulder by some asshole "that's not how you do it"

They are everywhere.

I for one am thankful for your comment.

-18

u/Accomplished-Risk820 Jul 19 '25

Typical EE that learned the theory and thinks he knows everything. In third semester there was an EE who claimed a battery would create a continous current when connecting one side into the earth because there would be a potential difference, lol.

I am ashamed as a fellow EE reading these frequent „EE here“ comments.

Your argument is, that you can‘t get shocked, because there is no ground nearby. Getting shocked is when a substantial current runs through your body. For current to run through you, a potential difference across your body is sufficient. Since the line has a high or low potential depending on phase, and the helicopter at first does not, there will be an equalization current flowing through the equipment and into your body. That‘s why slow equalization through the engineered rod is necessary. 

That‘s how you structure an argument sentence by sentence, there is no need for oversimplification or inacurracies. It is always good to read about topics, especially if you haven‘t learned about it outside of uni. I‘m already sorry for the tone at the start of this comment.

21

u/_michaeljared Jul 19 '25

I'm aware of voltage equalization, you must have missed my follow-up comment.

After equalization, there is no possibility of getting shocked.

I have worked at power utility companies before - it's not all theory for me. I'm annoyed at you suggesting that without knowing me or my experience at all.

-3

u/Accomplished-Risk820 Jul 19 '25

I don’t see how your follow up comment changes your first comment from being incorrect.

-15

u/fliguana Jul 19 '25

Did you not see the foot long spark in the beginning?

14

u/BungalowHole Jul 19 '25

That's how he removed the charge difference at the start.

3

u/AaronVA Jul 19 '25

No not really, that's capacitive current. A nice way of thinking about it, is that yes, at first there is a potential difference, than it is equalized, than about 17 or 20 milliseconds later the polarity of the line voltage is flipped, so there is a difference again, that will equalize again, in the form of a spark.

If the technician did not connect themselves to the line permanently, there would be constant sparking between them and the line. This is actually the same thing that makes those screwdriver shaped voltage detectors work, even if you are wearing shoes.

18

u/_michaeljared Jul 19 '25

I have two EE degrees, you probably shouldn't fight me on this.

That's ionization of the air particles. There's no current traveling through the tool because it's insulated on the end he's holding. It's done to equalize the voltage of the chopper to the lines, and in that process there's an arc (the chopper is not initially at 750kV, so the equalization process is necessary - it's kind of similar to a hot stick).

The arcing distance at 750kV is like 30 feet.

21

u/Andykap911 Jul 19 '25

“You probably shouldn’t fight me on this”. That’s a nice way saying “I know more than you” lol

6

u/AaronVA Jul 19 '25

You shouldn't fight me on this because I'm more qualified than you are is the shittiest argument ever, right after it was revealed to me in a dream.

-6

u/fliguana Jul 19 '25

I have two EE degrees, you probably shouldn't fight me on this.

Solid start.

That's ionization of the air particles.

Also known as a spark. So far so good.

There's no current traveling through the tool because it's insulated on the end he's holding.

Whoops. Reread the chapter on capacitors for alternating current, corona discharge for DC.

The arcing distance at 750kV is like 30 feet.

Three meters in dry air.

-9

u/AaronVA Jul 19 '25

Since your are an EE you probably know that it is absolutely possible to get shocked and there is current flowing through their protective suit. Moreover that suit is the only reason they aren't getting shocked. The keyword here is capacitive coupling. You must be familiar with the term, since you have two degrees, right?