I saw this in a doctors house once. The outlet was in a small room on the 2nd floor of the house, and had seperate wires going to a small room under the basement stairs. I assume that this would have, at one point, housed batteries or rectifiers, which were then wired to a radio set upstairs.
The same room also had one of those non-nema type radio combo outlets. The ones where the bottom half is for AC and the top half is aerial & ground. I think that was a later installation, though.
