This is what happened to us by using a portable heater. You can see the heater in the center of the photo at the link below. The wiring behind the wall overheated and failed spectacularly. Consider yourself warned . . .
https://photobucket.com/u/BraveMan_photos/p/f62d4689-bc1b-48eb-8318-f0e6a2a9c41e
BTW, if you want your home thoroughly trashed, invite the local Fire Department.