A very common type of 3-way electrical diagram is when the power supply wire moves from one switch to the second switch and finally terminates at the fixture. This wiring diagram shows both buttons aligned with the fixture at the end. You can use tools or colors to label the different types of wires used and use different line styles to show charged or uncharged wires.
In building wiring, multiway switching is the interconnection of two or more electrical switches to control an electrical load from more than one location. A common application is in lighting, where it allows the control of lamps from multiple locations, for example, in a hallway, stairwell, or large room.
In contrast to a simple light switch, a single-pole, single-throw (SPST) switch, multiway switching uses buttons with one or more additional contacts, and two or more wires are run between the switches. When the load is controlled from only two points, single-pole, double-throw (SPDT) switches are used. Double pole, double throw (DPDT) switches allow control from three or more locations.
In alternative designs, low-voltage relay or electronic controls can switch electrical loads, sometimes without the extra power wires.