What is inside one of those things? The folks over at Northstreetlabs have set out to answer just that question. You’ve seen these things before, and if you’re uneducated on the subject like myself, you just assumed they were there to stop a possible connection from a power line to the pole/building to which it is attached. Apparently that is part of their purpose. When presented with lightning, however, they turn to conductors allowing the lightning to pass to ground.
You can see their teardown in video form, as well as an explanation of how exactly they work on their site.

Filed under: teardown