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Comment by hwillis | Hacker News Reader

It can even kill tons of animals/people at once[1]. Four legged animals are more vulnerable than humans, since the voltage across your heart depends on how far apart your feet are. Also, we wear shoes.

Imagine how spooky it would be to be struck by ground current without understanding... Whether or not you survive could depend entirely on what direction you're standing. One direction will mean your feet are at different voltages and current jumps into your nice conductive veins and arteries, all passing right through your heart. The other direction means the front and back of each foot is at different voltages, and you may not even feel it. Hundreds of people just drop dead of heart attacks around you.

[1]: https://www.theverge.com/2016/8/29/12690402/lightning-strike...

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Just an aside, a term for this is 'potential gradient' (potential as in voltage, not probability :)

Well, that would be the ground current of a lightning strike, the induced ground current of a solar event is much much lower, it only plays a role with long wires.

FUD. It’s not lightning.

The effect is the same, does not really matter what causes the current gradient in the ground.

You need a huge voltage density. Ten volts between your feet is going to do nothing at all.

> You need a huge voltage density.

Does voltage density make any sense?

Probably meant gradient.

Fun fact, voltage gradient across cell membranes is typically megavolts per meter. At scale that is millivolts per nanometer, but the field strength is the same either way. Membranes are badass.

EDLC's operate at several gigavolts per meter, across a gap only atoms thick. They actually do it the same way as a cell wall -ELD stands for electrostatic double layer- by lining up two sheets of polar molecules, with charges facing each other.

I'm not aware of anything like "voltage density", what do you mean by that?

The potential gradient is the thing that kills you. It can either be created by a lightning strike or by voltage induced into the ground as mentioned here.

I'm talking about the potential gradient without bringing up new terminology.

> It can either be created by a lightning strike or by voltage induced into the ground as mentioned here.

If 'it' is lethal levels, then I don't think that 'or' is correct.

Doubt is was meant as FUD. Normal confusion suffices.

Ground currents are interesting however they occur, and are novel to many. The remarks were correct about lightning.

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