I am showing 15.6 volts on my outlet hot wires, even though power is not on that circuit. Here's the background. I have just put in a new room in my basement. The room has 6 outlets around the perimeter and 10 "can" lights in the ceiling on 2 switches. All electrical is run in conduit and the hot wire comes from a 20A circuit and all wiring is 12ga. solid copper. All is installed in metal boxes. All commons are twisted tightly together and wire nutted. I used a blue wire for one light circuit, a yellow wire for the 2nd light circuit, and black for the wall outlets. When I have the lights on in the room, I get 15.6 V showing on the black wire for all of my wall outlets. Because all of this is now behind sheetrock, and several of the runs are through flexible whips, it is impossible to pull out or pull back any of the wires. What is going on, and what are possible solutions?