Tracks and Connections 3.1 Q: Why doesn the third rail short out when it gets wet or rained on?
Well, this is really a question for an engineer and I’m an urban planner, so I’ll do my best. Basically, water can only make something short out if something else is grounding that object. Because the various places where the third rail is connected to something else (i.e. the ground, a power source, etc.) are insulated, there’s nothing to cause a short. The only way it could short out as a result of water is if it were completely submerged and thus the water were touching something else at the same time or if it similarly acted as a conduit between the third rail and another object (like, say, a person).
