"rck" wrote:

I had a house like that. The "duct" was the space between the joists with
sheet metal nailed to the bottom of the joists. I hired an electrician to
wire from one side to the other. He went all the way around the cellar, said
there was no other way to cross the duct.

Must be a recent code change in your area or overkill. Those types of ducts are
usually return air so temp is not a concern. There wouldn't have been any
problem drilling a hole on each side and running the romex straight through.
Caulk the holes when done.