The procedure allows for controlling a light fixture from two different locations. This is accomplished using specialized switches that, unlike standard single-pole switches, have three terminals and permit the circuit to be completed through either of two pathways. The configuration differs significantly from that used for a single-pole switch, requiring careful attention to wiring connections to ensure proper functionality.
This method offers enhanced convenience in residential and commercial settings, eliminating the need to traverse a room to operate a light. Historically, this type of electrical control system emerged as a practical solution for illuminating hallways, stairwells, and large rooms with multiple entry points. Its widespread adoption reflects the value placed on accessibility and ease of use in electrical systems.