Electrical receptacles

In the United States, most standard home electrical circuits are on a 120-volt line. All conventional duplex receptacles have two places to plug-in devices. As shown in the illustration, contemporary receptacles have a half-round hole that receives the grounding plug on an electrical cord. A contact leads from this hole to a green grounding screw that should be connected to the house ground (metal conduit or a green wire) to provide protection against shock when an appliance is plugged in.

Some receptacles in older homes don't have grounding plugs-they have only the paired slots. If your home's receptacles are like these, you've probably discovered grounding adapters, those little plugs that convert the end of a three-pronged plug to two prongs. If you use one of these, be sure to attach the grounding metal flange or green wire to the wall receptacle's center screw (which must be grounded). Otherwise, you'll defeat your electrical system's safety grounding.

Outdoor receptacles are mounted with special covers that seal the weather out (standard types are not safe for outdoor use).

A ground-fault circuit interrupter, also called a GFI or GFCI, shuts off a circuit instantly if it senses a hazardous short.

Receptacles for 240-volt appliances, such as dryers, air conditioners and electrical ranges, use receptacles with plug configurations that are different than those on standard receptacles. (Never try to force an electrical cord's plug into a receptacle that doesn't match.)

MORE ABOUT:
/ Electric meter / / Electrical service / / Elecrtic panel & circuit breakers / / When lights go out /
/ Main panel & subpanels / / GFCI breakers / / Switches / / 3-way switches /

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