receptacle
A contact device installed at an outlet for the connection of an attachment plug (typically by receiving the plug's prongs) to supply portable appliances or equipment.
receptacle: the socket that takes the plug
A receptacle is the fixed contact device mounted in a wall, panel, or equipment frame that receives an attachment plug to complete an electrical circuit. It houses female contacts (slots or holes) sized and spaced to match the male prongs of a mating plug, and it connects those contacts to the supply conductors behind it. The receptacle is the stationary half of the connection; the plug is the removable half.
Receptacles are rated by voltage, amperage, and phase configuration. A 120-volt, 15-ampere household receptacle in North America has two parallel slots and a U-shaped ground hole. A 240-volt, 50-ampere receptacle for an electric range has three or four large holes arranged in a triangular or rectangular pattern. Industrial three-phase receptacles come in 30, 60, 100 ampere and higher ratings, often with locking ring connectors (NEMA L types) that resist accidental disconnection. The contact material is typically brass or copper alloy, sometimes silver-plated for higher reliability.
Receptacles fail when internal contacts loosen, corrode, or arc. Loose contacts cause heat buildup and potential fire; corrosion increases resistance and voltage drop. Arcing happens when a plug is partially inserted or withdrawn under load, or when moisture enters an outdoor or wet-location receptacle. GFCI (ground-fault circuit interrupter) receptacles detect leakage current and trip in milliseconds, protecting against shock. AFCI (arc-fault circuit interrupter) receptacles detect the electrical signature of arcing and shut down the circuit.
Receptacles are classified by their NEMA or IEC configuration number. NEMA 5-15R is the standard two-slot 120-volt North American receptacle. NEMA 6-20R is a 250-volt, 20-ampere receptacle with different slot geometry to prevent mismatched plugging. IEC (International Electrotechnical Commission) configurations are common in industrial settings and differ from NEMA types. Locking (twist-lock) receptacles such as NEMA L14-30R have a bayonet-style keyed connection that requires a quarter-turn of the plug to seat and unseat; they are standard for high-power portable equipment like welders and temporary power distribution.
Receptacles are installed at the end of a circuit, downstream of protection (breaker or fuse) and any switches. The conductors are terminated under screw clamps or push-in terminals inside the receptacle body. Proper torque, terminal type, and wire gauge are critical: an undersized wire or loose connection can overheat the receptacle and melt its housing. Outdoor and damp-location receptacles must have weatherproof covers and corrosion-resistant materials. The term receptacle comes from its function: to receive the plug.