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Light switch product information

The light switch as been around since electric light was invented. During that time, manufactures have made countless changes to the basic design, trying to make switches that stand out from the competition. Light switches are classed as either mechanical or electrical, depending on the type of actuator used to bring the contacts together. Mechanical light switches include toggles, push buttons, and rockers. Electrical light switches include clappers, touch pad switches, and timers. While not technically a light switch, dimmers are used with them to control the brightness of lights.

The basic parts of a light switch are the wall bracket, switch unit, and face plate. The wall bracket is fastened inside a wall cavity and holds the face plate flush against the wall. The screws holding the face plate to the wall bracket are often hidden behind small caps. These caps can be removed by inserting a knife under their edge and popping them off. The switch unit attached to the back of the face plate contains the actuator and contacts that control the flow of electricity. Face plates are interchangeable and many different designs are available.

There are a few unusual terms used to describe light switches. Closed means the circuit inside the switch is complete, and open means the the circuit is broken. The switch positions can be different in other countries, reversing the usual on and off positions. Poles refer to the number of circuits the switch supports, and throws refers to the number of contacts each circuit has. Most light switches are single-pole and single-throw (SPST), which means they have one circuit that connects to one contact.

Mechanical light switches are operated manually and use an actuator to move a pivoting contact. A spring keeps the actuator in place and stops the contact from moving back. The toggle light switch uses a small triangular toggle as the actuator, while the rocker light switch use a wide paddle. The mercury switch is a silent toggle switch that uses a bulb filled with mercury as the contact. As the bulb was tilted to one side by the toggle, the mercury would roll between two contacts and complete the circuit. However, mercury switches are not widely available any more due to concerns about the toxic effects of mercury.

Electrical light switches are operated remotely by using a relay for the actuator and contacts. When a small electrical current is applied to the relay coil, it draws its contacts together, turning the light on. When the current is removed, the contacts separate and the light goes off. The clapper light switch has a small microphone that detects the sound of clapping and turns the switch on or off. The touch pad switch uses a metal plate to detect a capacitance change when it is touched by the human body. The motion-detection light switch which uses an optical sensor to detect movement and turns the light on or off. Motion switches are used by driveway security lights, and also in hospitals to prevent the spread of infection through direct contact. Timers and wireless switches are also used to switch lights, along with other appliances.

The dimmer is a device that controls the current flowing through a light switch to the globes. They are usually placed side-by-side with light switches on face plates, or incorporated into the switch unit. While variable resistors can perform this function, it is more efficient to use a triacs or thyristor which don't waste as much power. Dimmers work great with incandescent lights, but they do not work with fluorescent lights that use a ballast to limit the current flow. There are some expensive fluorescent lights that are designed to work with dimmers though.

Light switches are so commonplace that they are taken for granted, but they should be treated with the same caution as any other electrical device. They should only be installed by an electrician because mains voltage can cause serious burns or even death. It is also important not to touch switches with wet hands because they are usually not waterproof, and the contacts can be quite close the switch gaps.

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