An electrical outlet is also known as a receptacle. A receptacle outlet is an electrical outlet with one or more receptacles installed. Most modern homes have receptacle outlets. The most common of these is the duplex receptacle outlet. It has two identical outlets, usually stacked one on top of the other.
Most homes have dozens of receptacles, and most of these are grouped into receptacle outlets. The most common outlet used in the United States is the 120 volt. This outlet includes three holes.
One small rectangular hole conducts electricity through the plug to the device being powered. This is known as the hot slit. The other rectangular hole is neutral. The two rectangular holes are placed parallel to each other. Below these an arch-shaped hole takes the bottom prong of the plug, which grounds the device.
The common receptacle outlet is made of two or more of these 120 volt receptacles. Receptacles are inset in the wall and wired into the electrical system of the building. They are then covered with a plastic or metal plate so the wires are not exposed. Never remove the cover or insert anything except for a standard 120 volt plug into a receptacle outlet without first turning off the current to that outlet and using a current meter to check that the outlet is not live. Electric shock can cause heart attack or even death.
Special receptacle outlets are used in bathrooms, kitchens, and other damp areas to prevent electric shock. These special receptacles are called ground-fault circuit interrupter (GFCI) receptacles. They have standard three-prong outlets. In between the two outlets there are two buttons—a reset button and a test button. If the GFCI outlet senses that the current coming in is not equal to the current leaving the circuit, it will shut down, thereby preventing the flow of electricity to any device plugged into the receptacle outlet.
Since outlets present the risk of electric shock and fire, the National Fire Protection Organization covers receptacle outlet installation and placement in the National Electrical Code (NEC). Although the code itself is not part of United States national law, many individual states mandate that it must be followed. Before installing or altering any outlets or electrical systems, the home owner should always check the electrical code laws for his or her area. The best way to make sure that all rules are followed properly is by hiring a licensed electrician.