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Does a dry human body in contact between 230 volt mains voltage and ground has any form of capacitance ? Shouldn't there be some, or else is it just resistance ? I was thinking whether the Xc component plays any part when a person gets electrocuted


marked as duplicate by winny, Enric Blanco, Rev1.0, PeterJ, laptop2d Jun 26 '17 at 6:46

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Capacitive reactance (Xc) is a measure of a capacitor's opposition to AC (alternating current). Just Like the Resistance. When you come to contact with AC, the opposition to current for a human body must be the total impedance, considering your body capacitance and resistance. Given by the Following Formulas.

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According to this Link http://van.physics.illinois.edu/qa/listing.php?id=6793 The external human body resistance is about 1k to 100k Ohms, and the internal resistance is 300 to 1000 ohms. Only a thin layer of dry skin separates the internal resistance from an external object.

The human body capacitance to a far ground is 100-200pF, which is really a minimum value. Noting that the Capacitive reactance depend on the frequency.

So your overall body impedance will be quite significant because of the very small capacitance that produce a big Xc in the range of Mega Ohm. Helping to limit how much current can traverse your body.

But note that you only need to pass a current of (6 to 200 mA for 3 seconds) to make it fatal, and that's can happen when your body becomes sweaty decreasing your overall impedance.

So yes your Xc does play a role during electrocution, since its part of your body impedance which is the opposition to current.

All note that these parameters are not constant they vary from body to body.


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