Wednesday, September 21, 2011
Everyone knows it is okay for birds to land on power lines. But you would never think of touching a power line, right? Well, if you could do it like a bird does, you would be fine. In this case the ninja thinks he is every bit a bird.
As long as he is touching just the power lines, there is no way for the current to complete a path. He probably feels a little tingle from the static charge, but nothing more. Unfortunately, he forgets to release before touching the fire escape railing. Once he touches the railing, there is a way for the potential on the power line to make its way to ground through the ninja and the fire escape.
The voltage on these lines is probably 7200 volts from wire to ground, which is a pretty common voltage for urban power lines. You can estimate the voltage based upon the size of the insulators on the pole. Higher voltages require bigger insulators. These insulators are pretty small, so the voltage is fairly low, at least in the world of high voltage. In the world of “will-it-kill-me”, it is more than high enough.
Mark Robison, PE