How to Wire a Three Way Switch

This is a basic drawing of three way switch wiring. There are still a number of ways to wire a three way switch.

If you are doing this yourself, I am going to assume you are going to add a three way switch to you existing switch. To do that you need 14/3 wire, and simply run that from your existing single switch to your new three way switch.

The single switch needs to be replaced with a three way. The new three way will have 2 brass screws and one black screw. One of the wires off the existing switch, presumably black, will go to the black terminal of the new three way. Then the other wire off the switch, presumably black also, will terminate to the black of the 14/3 you just pulled in. Then the white and red terminate to the brass screws.

Now your second switch simply gets the black wire to the black screw. The white and red terminate to the two brass screws on the three way switch.