Light switches are some of the most basic and essential home electrical components. A light switch opens and closes electrical circuits to allow power to flow through lights. Light switches have evolved from a simple on/off toggle, and now have wider ranges of control to allow dimming, delayed fade, and programmable settings to turn on or off at certain moments. Switches can operate with timers, keys, and photoelectric eyes that sense daylight. They can also be paired with electrical outlets. All electrical switches range from single pole to four way switch and carry a range of functions for powering lighting and appliances.
Single Pole Switches
The single pole switch is a general purpose switch that turn a light on and off from a single location. The single pole switch is characterized by two brass terminal screws with one wired to the incoming black hot wire and the other to the outgoing white wire. There may also be a grounding terminal for the ground wire. This is found on all modern single pole switches. These are the simplest switches since flipping the lever simply activates or breaks the circuit to turn lights on or off in a single location. For light control from multiple locations, you need to use three or four way switches.
Three & Four Way Switches
Often you want to be able to control lights from multiple locations. In these instances, three way or four way switches are what enable you to control lights from more than one location. Three and four way switches are typically used at the ends of stairways or hallways or on opposite ends of a large room. These activate or break the circuit from multiple locations for convenience. These switches are characterized by the number of brass terminals as well, and include grounding screws. One terminal is known as the COM, or common terminal, and is used with the black hot wire. The other terminals are known as ‘travelers’ or leads for the switch. It does not make a difference which wire goes to which traveler terminal.
Four way switches lack the COM terminal and are used in between two three way switches to control an outlet from three or more locations.–sort of a facilitator switch. Dimmer switches can work in the same way and are positioned in the same places–each switch at one end of a hall, staircase, or room. Controlling lights through dimming from three or more locations also requires a four way switch. Understanding how light switches work is crucial to changing home switches or pinpointing the source of a dead outlet and making the necessary repairs.