The switches are the most common and important electrical devices in any hose. There are different types of switches and though they look the same when they are installed with their faceplates, the various switches function directly inside. The most common type of switches come in different styles such as toggle, rocker, slider, and push button. But the function and wiring are the same in all the styles.
Though the switches are used for lights, it can be used to turn on and off any electrical devices such as a fan or floor lamp.
Single-Pole Switch
The single-pole switch is used for the general purpose in the house such as control a light, receptacle, or other devices from a single location. The characteristic feature of the single-pole toggle switch is that it has an on and off marking on the toggle. However, you will not have the on/off marking even in some single-pole switches such as rocker style switches.
A single-pole switch has two brass-colored screw terminals connected to the hot or power source black colored wires. One brass terminal is designated for the incoming hot wire from the power source and the other is for the hot wire going out to the fixture. Most of the single-pole switches include a ground terminal for connecting the circuit ground wire.
The neutral white wires are not connected to switches. In case there are two neutrals in the box, these wires are joined so that they continue through the box without touching the switch. Or, a single neutral wire pass through the box. And in some cases, the white wire would be attached to the switch which functions as a hot wire. The white wire should be wrapped with black tape on it near the switch terminal to indicate the wire is operating as a hot wire and not a neutral wire.
Three-Way Switch
A three-way switch is always used in pairs. It allows controlling light or receptacle from two different locations. These switches do not have on and off marks as the on and off positions keep changing as the switches are used. The three-way switch has three terminal screws. The hot wire from the power source connects to the darkest screw terminal marked as “COM” for stands for common. The rest of the two terminals are called travelers and are interchangeable. For safety purposes, travelers must be always hot wires. The switch has a ground screw as well.
Three-way switches are usually found around the house such as ends of the staircase, in garages or basements with two entries, in hallways, and other places so that two separate switches can control one light.
Double-Pole Switch
This is commonly used in industrial applications. But it is used in some home wiring systems as well. A double-pole switch has on and off markings which help in controlling a device from a single location. The difference between a single-pole and double-pole switches is that the latter has four hot brass terminals, instead of two, and a ground terminal. This is done so that the user can connect it to two pairs of hot wires from a 240-volt circuit.
Double-pole switches are generally rated for 30 amps, compared to 15 or 20 amps with standard switches which help the switches to control power feeding higher-demand appliances, motors, and machinery.
Four-Way Switch
To provide control for an outlet or light fixture from three or more different locations, the four-way switch is used between two three-way switches. That is, if you want to have control from more than three locations—for example, five locations—you will use 2 three-way switches and 3 four-way switches between the 2 three-ways.
The four-ways switches look like the double-pole switch, but it does not have on and off markings. It has four terminals and a ground terminal. The four terminals are usually brass colored and there isn’t a “COM” terminal. The function of four-way switch is act as the switching device for the traveler wires between the three-way switches.