I want to connect a fan with light and pull chain only to a box that has the old wiring black and white to the new wiring black,white and green.Is this possible and how do I do it.
Knob and tube wiring should be replaced - I don't care what the grandfather clause says in the electrical code -- safety first.
First of all, you can do it only if the box is fan rated. A regular box won't handle the forces that a fan places on it. Unless the existing box is metal and grounded, you will just have to install the fan without the ground. If you make a mistake in the wiring, someone could get shocked, instead of the breaker tripping. However, since the fan is on the ceiling, it is unlikely that they would be grounded, and the shock would be uncomfortable, but not serious. If the box is metal and grounded, just fasten the green wire to it with a screw. Bottom line: It is possible, but there are potential problems that may be quite difficult to work around.
Jim W. is spot on. The old wiring may not have a grounding conductor, and the fan would not be grounded. Check to see if there is a old screw in the back of the inside of the box, that is holding down a bare wire. If so, as long as the ground wire has not been cut anywhere, and is still connected, it should be grounded. Any electrician can test it with a tester, and tell if the box is grounded. If not, you are connecting the green to the box, but it is not connected to anything. MAKE SURE THE BOX CAN HOLD THE FAN, and in the installation instructions, it tells you to add large wood screws, through the mounting bracket, into SOLID wood. If the fan is not tight, it WILL wobble..
Black to black, white to white, the ground goes to the metal box. Only use a light weight fan, less than 6 lbs. KT wiring should be replaced ASAP. The insulation on the old wiring deteriorates over the years with heat and become a fire hazard. Most insurance companies want that type of wiring removed.
