I always like to visit the traction displays at train meets. While at the Greenberg show today, I was looking at the East Penn display. They had one of their members stationed at a particular spot where the trolley poles on two of the streetcars kept coming off the wire. This spot happened to be an isolator on the overhead wire. We got to talking and he said some maintenance had to be done in that spot.
All of the traction displays I have seen always use the overhead wire to set up blocks. I'm wondering why the rails aren't isolated instead. This would eliminate the plastic isolators that can cause problems with the trolley poles.