I have a metal tornado shelter under the slab, residential. There is one 2"x2" vent pipe (box tubing) on the top of the shelter penetrating through the slab and into the wall of the home. The box tubing is 6" long. The customer doesn't want any new penetrations in the tornado shelter. They want a air vent attached to this vent pipe and an electrical wire ran into the shelter for power. I know there are some restrictions about running wire in a vent tube. Any Batman type methods I could use to do this legally? Other than the vent pipe, there is of course an access in the middle of the shelter for people to enter the shelter, but I couldn't run the wire into the shelter through the access hole.