Trainwire,
That stuff is legitimate. It's called flexible metallic conduit in the Code or Greenfield or "flex" in the real-world. It's very often used in short lenghts to make connections to equipment that vibrates, such as motors or transformers.
It's funny this should come up, because I was wondering about this practice the other day: Does anyone have any negative experience with non-flexible conduit being connected to transformers? The vibration is so slight that I have to question if FMC is even necessary. Especially since in many cases the pieces are of such a large diameter, and so short, that they aren't technically very flexible at all, and do very little to dampen the vibration of the tranny.
-John
