The Myth
A guy is wandering through a railyard drunk and needs to relieve himself. He makes sure no trains are coming and he starts to pee onto the third rail, which is electrical, and a current runs through his urine and kills him.
The Test
First the Mythbusters must determine if it is actually possible for urine to conduct electricty. They learn that the voltage of the third rail is 650 volts and they determine that the resistance of urine is 10,000 Ohms. Using Ohm's Law they determine that it can resistance 65 miliamps and all that is need to make you stop breathing is 30 miliamps. Now that they know it is possible to be killed through urine, they go about making a body out of ballestics gel and figure out how to make the dummy urinate. After many failures of making the dummy and success with urinating machine, they finally are able to test. They set up the dummy so that it will urinate onto a mock third rail that they set up. The first test shows no results. They decide to make the ground below the dummy wet and try again, however nothing happens. They try removing the shoes and making the ground wet again, however failure. They determine that the stream is not constant because by the time it has hit the rail it has broken up into drops. They increase the size of the tube that allows urine to exit and move the rail up so it is a few centimetres away. They try this time to success.
The Result
Busted. Although it is possible for someone to kill themselves by peeing on the third rail, it is very unlikely. (Note, this myth is revisited in Myths Revisited)
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I'm guessing the voltage in a power line is much greater than 650 volts.
