I had my "project house" rewired last year. My electrician ran 12-2 which had one white, one black and one bare ground wire. However, where we planned to put a ceiling fan with a light kit he ran 12-3. . . . one white, one black, one bare ground and one red. He said where we finally decided to put just a light fixture that the red one would be covered with a wire nut and tucked away. . . we could put a ceiling fan in later if we wanted.