How A 3 Way Switch Works. It's very easy to mix up three-way switch wiring when replacing a three-way switch. Then remove the light switch panel to see where the power.
The best example of this would be at either end of a long hallway, or at the top and One of the three terminals is "identified" (by using a different color) and is usually the bottom screw on the side with two screws.
Then remove the light switch panel to see where the power.
A three-way switch has three terminals, and the switch connects the first terminal to either the second or the third terminal, as shown here If you are trying to understand how a set of switches are wired in your house, using an ohmmeter or a continuity detector is the only way to reverse-engineer what. How to control a light from two switches. Before proceeding, make sure you are comfortable working with.