I just came across some of these in a 1930 house that are antenna/ground only, no power. Two of them are in the center of the rooms in the floor with no power nearby. I can't imagine why they put them there with no power. They are just a single, round receptacle just like the top half of the ones shown. I have pics but don't know how to upload them without using a host site and I no longer trust photobucket.
