This sounds like some of the things my DH has found while remodeling our condo. While the construction and walls between the units are great (and not done this way anymore), the electrical and plumbing was done in several weird ways, only apparent when the walls were knocked out. Then there was the day that he went over there, just to drop some stuff off. While in the basement, he heard some crackling.Turns out the breakers were done all wrong, and it is very likely our new house would have burned down, before we moved in. He fixed that and several other things, but a couple of these things required an electrician or plumber.