If you touch a live wire without touching the ground, do you get an electric shock?


by Gruxg
Tags: electric, ground, live, shock, touch, touching, wire
Gruxg
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#1
Nov4-12, 08:18 AM
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It is ussually thought that if you receive a shock touching only one cable is because you are not well isolated from ground. In theory, if you touch only one wire in one point and you are not conected to ground, you should not get a discharge (we all have seen small birds in the transmission lines). However, I have noticed that if I am standing on a plastic stool and not touching the ground anywere and I touch a live wire with one of those test lights like a screwdriver used by the electricians, it indicates current. This tester is only a light and a very high resistance between the wire and my finger, and it is indicating that the current is going into my body (with small intensity due to the high resistance of the tester). I guess my body is acting like a capacitor or someting like that. It is possible to receive a painful or dangerous shock if you are not grounded, only by the capacitive effect?.

And in a more general sense, if an large object (like a human body) is conected to one of the terminals of an AC generator but the circuit is open (no return cable) and there are no other objects close to the big body that can act as "the other plate of the capacitor", can there still be a current?. If the body is sufficient large, I do not find any physical reasons to think that this would not happen. However it breaks a bit with the common asumptions of the circuit theory.
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skeptic2
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#2
Nov4-12, 09:24 AM
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http://www.youtube.com/watch?v=9tzga6qAaBA
rcgldr
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#3
Nov4-12, 01:36 PM
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Note the guy in that video is wearing a "faraday cage" like suit. Since the guy on the wire provides an additional parallel path to the current flowing through the wire, a small percentage of current would flow through the guy if not for the "faraday cage" suit that carries that small percentage of current instead.

DrZoidberg
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#4
Nov6-12, 04:16 PM
P: 371

If you touch a live wire without touching the ground, do you get an electric shock?


No it doesn't break with circuit theory.
A human is usually modelled as having a capacitance relative to earth and a resistance.
So yes, if you touch an ac line there is a always a current flowing. That's also the reason why birds never land on high voltage power lines. They may land on medium voltage lines or on the ground wire of a high voltage power line. But never on wires carrying more than a few dozen kV.
spamctor
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#5
Nov6-12, 11:05 PM
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Just curious, let's say that someone hypothetically climbs a utility pole with no special equipment/clothing on and grabs a live wire. Will they get shocked? And if so, where is the current going through them grounding to?
rcgldr
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#6
Nov7-12, 03:25 AM
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Quote Quote by spamctor View Post
Just curious, let's say that someone hypothetically climbs a utility pole with no special equipment/clothing on and grabs a live wire. Will they get shocked? And if so, where is the current going through them grounding to?
Consider the person to be similar to an antenna connected to an 500,000 to 700,000 volt AC power source, there is current flowing through an "antenna" as the AC voltage at the powered end of the "antenna" cycles back and forth.


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