When my house was built a can was installed in the ceiling for a picture light connected to a switch on an adjacent wall. We discovered this after the drywall was installed and, since we did not want the picture light, the builder capped it off somehow and covered the can with a drywall patch of some sort. We would now like to be able to add more light to the room, in the center of the room. Is there a way to find this abandoned wire without guessing? There is no other load on that wire and we do not have access to the attic above this room. Thank you.