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Common Types of Household Electrical Switches
The wall switch is one of the most basic—yet most important—electrical devices in the home. There are several different types of switches, and although they may look the same when they are installed, and their faceplates are on, the various switches can function quite differently. All of the common types of switches come in different styles, such as toggle, rocker, slider, or push-button. The style usually does not affect the switch function and wiring.Continue to 2 of 5 below.
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The single-pole switch is the general-purpose workhorse of switches. It is used to control a light, receptacle, or another device from a single location. A characteristic feature of a single-pole toggle switch is that it has ON and OFF markings on the toggle. This is something you will not find on three-way or four-way switches.
A single-pole switch has two brass-colored screw terminals and is wired to the "hot" (current-carrying) wire, which is usually black. One brass terminal is for the incoming hot wire, and the other is for the outgoing hot wire to the device. Most single-pole switches also include a ground terminal for connecting the circuit's ground wire.
As a general rule, neutral (usually white) wires are not connected to switches. However, sometimes you may see a white wire attached to the switch, and this is when it is functioning as a hot wire. In this case, the white wire should have a wrap of black tape on it near the switch terminal to indicate that the wire is a hot wire and not a neutral wire.Continue to 3 of 5 below.
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The double-pole switch is commonly used in industrial applications but can be found in some home wiring systems. Like the single-pole switch, a double-pole has ON and OFF markings and controls a device or equipment from one location. The main difference is that a double-pole switch has four hot brass terminals (instead of two), plus a ground, allowing you to connect it to two pairs of hot wires from a 240-volt circuit.
Double-pole switches are commonly rated for 30 amps (compared to 15 or 20 amps with standard switches), so they can control higher-demand appliances, motors, and machinery.Continue to 4 of 5 below.
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Three-way switches are always used in pairs and allow you to control a light or receptacle from two different locations. These switches have no ON or OFF markings because the on and off positions will vary 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 "COM" for "common." The other two terminals are called "travelers" and are interchangeable. The switch also has a ground terminal.
The trick in replacing an old three-way switch is to mark the wire attached to the COM terminal before you remove the old switch. Since the other two are interchangeable, you can't get them wrong. If there is a white wire connected to a traveler terminal, it should be labeled with black tape to indicate it is hot.Continue to 5 of 5 below.
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The four-way switch is used in between two three-way switches to provide control for an outlet or light fixture from three or more different locations. If you want to have control from more than three locations—say five locations—you would still use two three-way switches (one on each end) and three four-way switches in between the two three-ways.
The four-way switch looks similar to a double-pole switch, except it has no ON or OFF markings. It has four terminals (plus a ground), usually brass-colored. There is no "COM" or "common" terminal, as in a three-way switch. The four-way switch functions as a switching device for the traveler wires between the three-way switches.