That is what they do -- the electrons all pass along the surface of a conductor, with none actually going through the conductor unless it's the shortest path to ground. If memory serves. But an EMP isn't a stream of electrons, it's an alternating electrical and magnetic wave at 90 degree angles that propagates through the air as pure energy. I mean... isn't it? So I don't see how a few bars is going to prevent it from reaching the inside of a cage?I think what you're thinking of is that a moving magnetic field causes electricity to move through a conductor in it's presence (electrons to travel). But that doesn't actually stop the wave I don't think... I know that the presence of a conductor simply by virtue of being there changes an electromagnetic field though, so it's conceivable it could stop an EMP... but I don't believe it actually does. I dunno.I'll look it up sometime... as soon as I finish with the 1.23 million other things I still have yet to look up... ::)