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it just does not make sense to me that electrons can move from sand or soil (sand and soil have very high resistivity to current flow) to our body. how is possible anyway?

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  • $\begingroup$ I once measured the resistance between two ground stakes about 15 feet apart as 5 kOhm. It was not very high. $\endgroup$
    – safesphere
    Oct 11, 2017 at 15:03

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And there is even a rubber or polyethylene shoe sole in between, both are excellent insulation material. But still (dangerous) current can flow from sand/soil through rubber or PE to the body. With AC or while charging with DC, the electrons do not need to pass through the insulation, as can be seen with capacitors. So the human body as one electrode and the earth as the other one build a complex system of capacitors, where the air surrounding the body may also be part of a complex combination of resistors and capacitors. That way, the electrons do not need to move through the insulation, they charge and discharge the capacitor system between earth and body. Another way is simply high voltage, as seen f.e. in thunderstorms, where DC voltages can cause a break through, i.e. electrons move or tunnel across insulators. So insulators have always a maximal voltage or electric field before they fail. In case of lighting, even many hundreds of meters of air ( which is normally a good insulator) may fail and deliver a path for the current. Sand and soil is a complex mixture containing also some water and air, maybe ionized salt particles and minerals, and there is the air above the earth containing some water and dust particles, which is both in "contact" with the earth surface and the human body, which results in a low resistance under certain conditions.

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  • $\begingroup$ Have you heard of earthing? The isolation in our shoes does prevent a lot of electrons from moving into our bodies. Several studies show the effects. $\endgroup$
    – Tigerware
    Sep 15, 2023 at 17:21
  • $\begingroup$ Have you heard of capacitors? The isolation in those capacitors does only prevent dangerous situations when DC is supplied. For normal household AC @230V, the soles and the air build a complicated network which can result in currents above 15mA into the body. $\endgroup$
    – xeeka
    Apr 11 at 10:01

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