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Explaining How a Light Switch Works

Matte Black 2-Toggle Light Switch Cover

Brushed bronze wall plates look beautiful, and they make a great addition to almost any home. Wall plates are sometimes overlooked when it comes to adding the finishing touches to home design, but they can be very effective in completing a look. Unfortunately, most homeowners don't pay very much attention to the light switches themselves. If you're considering updating or renovating your home, it's worth considering your electrical system and the light switches themselves. Learning how a light switch works should give you a bit of insight into these important details.

Single-Pole Switches

These are the on-and-off switches that are present in most houses, apartments, and offices. A single-pole switch is also known as a single-throw switch or single-location switch. These switches are the only switches that feature markings for on and off. The term single-pole indicates that the switch has only one "hot" wire connected to it. A "hot" wire is a wire that conducts electricity. The term single-throw implies that when you flip the level, it connects to only one outgoing wire. This is generally a wire leading to a light fixture or an outlet.

Inside of a single-pole switch is a metal gate. When you flip the switch, it causes the gate to either open or close. When the gate is closed, it completes the circuit and allows electricity to flow. This is the on position. When the gate is opened, it breaks the circuit and prevents the flow of electricity. This is the off position. Gateways can be mechanical and spring-loaded, or they may use a vial of mercury to help complete the circuit. Switches with mercury are sometimes called "quiet" switches. They don't have the snap or click that many people associate with light switches. While the spring-loaded mechanical switches are more common, they are prone to failure as the spring starts to wear out. The mercury vial switches are longer-lasting, but they tend to be more expensive as well.

Three-Way Switches

These switches are always used in pairs. Three-way switches have a green grounding screw, a dark-colored screw terminal known as the common, and a "hot" wire that brings in the electricity. Another two screw terminals are light in color and connect to a pair of wires. These are known as travelers, and they run between the pair of switches. A three-way switch could also be called a single-pole and double-throw switch. It has only one "hot" wire, but it has two ways to turn it on or off. Three-way switches are typically used to control a light fixture from up and down stairs or from across a large room. On and off are not marked on the switch, because these switches can turn lights on or off from either the top or bottom position.

Four-Way Switches

Four-way switches are exceedingly rare. They're used in conjunction with a pair of three-way switches. Internally, you can think of a four-way switch as having an X-shaped configuration. You can identify a four-way switch by four screw terminals in addition to the green grounding screw. It's a double-pole and double-throw switch because it has two "hot" wires and traveler wires. The double-throw function is possible because of the two traveler wires that pass from the four-way switch to the next switch. To simplify, a four-way switch may open a closed electrical pathway, or close an open pathway.

The mechanisms hiding behind wall plate switches can be surprisingly complex. Contact Wallplate Warehouse at (888) 643-3744 to discover functional and beautiful plates and switches.

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