The four-way switch is commonly used to control the light from more than two different places and it is simply a cross switch or cross over switch which has two states. So now you can on and off the light by the first switch and the same for the second switch or you can on the light with the first switch and off with the second switch. In between the two switches, the two lines are called travelers. Now you need different kinds of switches called three-way switches probably because they have three contacts. Let say you have two different entrances to a room. The basic circuits of on and off the light is shown in the below figure. Let start with the basic idea of the light switch in an electric circuit. The US terminology used in this explanation. In the US they refer to a three-way switch and four-way switch. In the UK they refer to two-way switch and cross over switch.

The terminologies related to switches are different between the US and the UK. When the switch is in off position then the circuit is said to be open circuit. There are three types of circuits they are open circuit, close circuit, and short circuit. The switch is on when the COM terminal and L 1 terminals are connected and the switch is off when the COM and L 2 terminals are connected. This configuration is similar to the EX-NOR gate in digital electronics.įig (a) is the two way light switch mechanism, fig (b) is the single gang switch face and fig (c) is the single gang two way light switch. The two-wire control two-way switch is shown in the below figure. The L 1 and L 2 terminals of both the switches are connected together. The first switch COM terminal connected to phase and second switch COM terminal is connected to one end of the bulb and the other end of the bulb is connected to neutral AC supply. The two-wire control two-way switch mostly will find in some of the industrial settings and old homes. Two Way Switch Front and Back ViewĪlternative Method of Two Way Switch Wiring The two-way switch front and the back view is shown in the below figure. This is the function of two way switch wiring. Similarly, the light is ON when the first switch COM terminal is connected with the L 2 terminal and the second switch COM terminal is connected with the L 1 terminal. The light is ON when the first switch COM terminal is connected with the L 1 terminal and the second switch COM terminal is connected with the L 2 terminal. The light is OFF when COM terminals of both the switches are connected with L 1 or L2 terminals. The configuration of the three-wire two-way switch wiring is similar to the EX-OR gate in terms of digital electronics.

3 way switch diagrams