Three-phase electric power is a common type of alternating current used in electricity generation, transmission, and distribution. It is a type of polyphase system employing 3 wires and is the most common method used by electrical grids worldwide to transfer power.
In electrical engineering, ground or earth is a reference point in an electrical circuit from which voltages are measured, a common return path for electric current, or a direct physical connection to the earth.
Electrical wiring in North America follows regulations and standards for installation of building wiring which ultimately provides mains electricity.
A residual-current device (RCD), or residual-current circuit breaker (RCCB), is a safety device that quickly breaks an electrical circuit to protect equipment and to reduce the risk of serious harm from an ongoing electric shock. Injury may still occur in some cases, for example if a human receives a brief shock before the electrical circuit is isolated, falls after receiving a shock, or if the person touches both conductors at the same time.
The National Electrical Code (NEC), or NFPA 70, is a regionally adoptable standard for the safe installation of electrical wiring and equipment in the United States. It is part of the National Fire Code series published by the National Fire Protection Association (NFPA), a private trade association. Despite the use of the term "national", it is not a federal law. It is typically adopted by states and municipalities in an effort to standardize their enforcement of safe electrical practices. In some cases, the NEC is amended, altered and may even be rejected in lieu of regional regulations as voted on by local governing bodies.
A distribution board is a component of an electricity supply system that divides an electrical power feed into subsidiary circuits while providing a protective fuse or circuit breaker for each circuit in a common enclosure. Normally, a main switch, and in recent boards, one or more residual-current devices (RCDs) or residual current breakers with overcurrent protection (RCBOs) are also incorporated.
An arc-fault circuit interrupter (AFCI) or arc-fault detection device (AFDD) is a circuit breaker that breaks the circuit when it detects the electric arcs that are a signature of loose connections in home wiring. Loose connections, which can develop over time, can sometimes become hot enough to ignite house fires. An AFCI selectively distinguishes between a harmless arc, and a potentially dangerous arc.
Industrial and multiphase plugs and sockets provide a connection to the electrical mains rated at higher voltages and currents than household plugs and sockets. They are generally used in polyphase systems, with high currents, or when protection from environmental hazards is required. Industrial outlets may have weatherproof covers, waterproofing sleeves, or may be interlocked with a switch to prevent accidental disconnection of an energized plug. Some types of connectors are approved for hazardous areas such as coal mines or petrochemical plants, where flammable gas may be present.
A split-phase or single-phase three-wire system is a type of single-phase electric power distribution. It is the alternating current (AC) equivalent of the original Edison Machine Works three-wire direct-current system. Its primary advantage is that it saves conductor material over a single-ended single-phase system, while only requiring a single phase on the supply side of the distribution transformer.
Ground and neutral are circuit conductors used in alternating current electrical systems. The ground circuit is connected to earth, and neutral circuit is usually connected to ground. As the neutral point of an electrical supply system is often connected to earth ground, ground and neutral are closely related. Under certain conditions, a conductor used to connect to a system neutral is also used for grounding (earthing) of equipment and structures. Current carried on a grounding conductor can result in objectionable or dangerous voltages appearing on equipment enclosures, so the installation of grounding conductors and neutral conductors is carefully defined in electrical regulations. Where a neutral conductor is used also to connect equipment enclosures to earth, care must be taken that the neutral conductor never rises to a high voltage with respect to local ground.
An autotransformer is an electrical transformer with only one winding. The "auto" prefix refers to the single coil acting alone, not to any kind of automatic mechanism. In an autotransformer, portions of the same winding act as both the primary winding and secondary winding sides of the transformer. In contrast, an ordinary transformer has separate primary and secondary windings which have no metallic conducting path between them.
Electrical wiring is an electrical installation of cabling and associated devices such as switches, distribution boards, sockets, and light fittings in a structure.
Electrical wiring in the United Kingdom is commonly understood to be an electrical installation for operation by end users within domestic, commercial, industrial, and other buildings, and also in special installations and locations, such as marinas or caravan parks. It does not normally cover the transmission or distribution of electricity to them.
An earthing system or grounding system (US) connects specific parts of an electric power system with the ground, typically the Earth's conductive surface, for safety and functional purposes. The choice of earthing system can affect the safety and electromagnetic compatibility of the installation. Regulations for earthing systems vary considerably among countries, though most follow the recommendations of the International Electrotechnical Commission. Regulations may identify special cases for earthing in mines, in patient care areas, or in hazardous areas of industrial plants.
IEC 60906-1 is an international standard designed "to provide a standard for a safe, compact and practical 16 A 250 V AC system of plugs and socket-outlets that could be accepted by many countries as their national standard, even if not in the near future." The standard was originally published by the International Electrotechnical Commission in 1986; the current edition is ed2.0 published in 2009. Although it is almost identical to the Swiss SEV 1011 T12 plug for 10 A 250 V a.c. standardized in 1937, its dimensions are slightly different and its polarization is flipped. As of July 2014, only South Africa has introduced a standard based closely on IEC 60906-1. Brazil used it as the basis for its NBR 14136 standard, but this is not compatible with IEC 60906-1. In 2017 the European Union (EU) published recommendations advising against the harmonisation of domestic plug and socket systems in the EU.
NEMA connectors are power plugs and receptacles used for AC mains electricity in North America and other countries that use the standards set by the US National Electrical Manufacturers Association. NEMA wiring devices are made in current ratings from 15 to 60 amperes (A), with voltage ratings from 125 to 600 volts (V). Different combinations of contact blade widths, shapes, orientations, and dimensions create non-interchangeable connectors that are unique for each combination of voltage, electric current carrying capacity, and grounding system.
A stage pin connector, also known as a grounded stage pin (GSP) or grounded pin connector (GPC), is a standard cable type for theatrical lighting in North America and in many countries in the theatre world.
In an electric power system, a fault or fault current is any abnormal electric current. For example, a short circuit is a fault in which a live wire touches a neutral or ground wire. An open-circuit fault occurs if a circuit is interrupted by a failure of a current-carrying wire or a blown fuse or circuit breaker. In three-phase systems, a fault may involve one or more phases and ground, or may occur only between phases. In a "ground fault" or "earth fault", current flows into the earth. The prospective short-circuit current of a predictable fault can be calculated for most situations. In power systems, protective devices can detect fault conditions and operate circuit breakers and other devices to limit the loss of service due to a failure.
Powerlock is a range of single-pole electrical connectors used for temporary high-current, low-voltage applications, similar to but considered safer than camlock connectors. Originally developed by Litton Veam in the mid-1990s, VEAM Powerlock is now a brand of ITT Cannon. Compatible versions are also available from other manufacturers.
In building wiring installed with separate neutral and protective ground bonding conductors, a bootleg ground is a connection between the neutral side of a receptacle or light fixture and the ground lug or enclosure of the wiring device.
