Three-way switches are commonly used to control a light fixture from two different locations.We use light switches every day, and yet have you ever seen the inside of one? In this video we open up 3 types of light switches: the basic light switch, 3-Way light switches, and 4-Way light switches.
source/image(PrtSc): Branch Education
We also explore how they can be wired together to turn on one or multiple lights.A normal switch has two terminals that are either connected or disconnected. A three-way switch has three terminals, and the switch connects the first terminal to either the second or the third terminal.
Electrically, a typical “3-way” switch is a single pole, double throw (SPDT) switch. By correctly connecting two of these switches together, toggling either switch changes the state of the load from off to on, or vice versa. The switches may be arranged so that they are in the same orientation for off, and contrasting orientations for on.For example, a long hallway or stairway might use a pair of three-way switches at each end so that lights can be turned on when approaching one end of the hall or stairway, then shut off from the other end.
When both toggles are up or both are down, the circuit is complete and the light fixture will be illuminated. When the toggles are in opposite positions, the circuit is interrupted and the light fixture turns off. This allows either switch to control the on-off function of the light fixture at any time./Branch Education