Haven’t you ever watched a rat drag a bone across a subway platform and wondered: “why don’t those little bastards get fried when they set paw on the third rail?” I mean, if you or I were to touch that rail we’d instantly be barbecue, but rats can come and go as they please. Wassaupwitdat?
Well it turns out that being small has its advantages. The rats are too small to complete a circuit (of death). Michael Pollak of the NY Times has the explanation:
They don’t form a grounding connection between the third rail and the track bed, transit officials said. “In order to be electrocuted you need to complete a circuit, which means you need to touch the third rail and the ground,” said John Campbell Jr., assistant chief electrical officer for New York City Transit. “It’s the same reason birds can sit on live uninsulated electric lines and not get electrocuted: there is no path for the current to flow.”
If a rat, bored with jumping, were unwise enough to reach up and touch the live part of the 600-volt third rail while keeping its other paws on the ground, it would be toast. But rats don’t do that. In most cases, either their bodies are not long enough to form a grounding connection, or their travels do not give them any reason to climb that way.
That makes it sound like I could survive jumping on the third rail by making sure to not touch the ground at the same time. Of course, I’ll never know. Oh well; answer one question, raise another. [NY Times via Second Ave Sagas]