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Encyclopedia > Electrical cable

Power cable (a type of electrical cable) is an assembly of two or more electrical conductors held together with, and typically covered with, an overall sheath. The conductors may be of the same or different sizes, each with their own insulation and possibly a bare conductor. Larger single conductor insulated cables are also called power cables in the trade. A hybrid cable may also include other conductors (such as fiber optics), AC mains (household power) conductors, low-voltage data signalling or control conductors, and radio frequency conductors (such as coaxial cable). The sheath may be of metal, plastic, ceramic, shielded, sunlight-resistant, waterproof, oil-resistant, fire-retardant, flat or round, and may also contain structural supports such as Kevlar, aerial wire, or other high-strength materials. A cable is two or more wires bound together which may be bare or covered or insulated. ... It has been suggested that Conductor (power engineering) be merged into this article or section. ... This page refers to thermal insulation. ... Fiber Optic strands An optical fiber in American English or fibre in British English is a transparent thin fiber for transmitting light. ... Type F Mains power plug & socket The term mains usually refers to the general purpose AC electrical power supply (as in Ive connected the appliance to the mains). The term is not usually used in the US and Canada, where it is known as household, or domestic power. ... Rough plot of Earths atmospheric transmittance (or opacity) to various wavelengths of electromagnetic radiation, including radio waves. ... Coaxial cable is an electrical cable consisting of a round conducting wire, surrounded by an insulating spacer, surrounded by a cylindrical conducting sheath, and usually surrounded by a final insulating layer. ... Kevlar, also known as Twaron and poly-paraphenylene terephthalamide, is a synthetic fibre that is five times stronger than steel, weight for weight. ...


Common types of general-purpose cables used by electricians are defined by national or international regulations or codes. In the USA the definition is contained in the National Electrical Code or other International standards and are generally defined according to the conductors and the materials used, shape, and intended usage for the sheath. The conductors are usually copper or aluminum, stranded, solid, and of various diameters as determined by the required current of the application. As mentioned, they may be individually insulated or bare. There may also be one or more conductive sheaths for mechanical protection, equalization of the electric stress on cable insulation (in circuits above 2400 volts) and for collecting the a/c leakage currents. Conductive sheaths will not reduce magnetic induction from cable to cables in circuits carrying large currents. These conducting sheaths are bonded to earth through connection to equipment enclosures or by a dedicated grounding conductor. An electrician is a tradesman specializing in electrical wiring of buildings and related equipment. ... The National Electrical Code is Part 70 of a set of codes and standards set forth by the National Fire Protection Association (NFPA). ... Standards are produced by many organizations, some for internal usage only, others for use by a groups of people, groups of companies, or a subsection of an industry. ... The word current usually implies a flow or movement. ...


For example, NEC Type UF (underground feeder) is a non-metallic, moisture-resistant jacket containing conductors having moisture-resistant insulation suitable for direct burial in the earth or in interiors in wet, dry,or corrosive locations. Type AC is a fabricated assembly of insulated conductors in a flexible metallic enclosure. Some are made by twisting an interlocking metal tab or other metallic sheath around the insulated conductors. BX, an early genericized trademark of the General Electric company was used before & during WWII, of particular design. Some AC are rated for the flexible metal to have limited grounding currents. In Canada, type TECK cable, with a flexible aluminum or steel armour and overall flame-retardent PVC jacket, is used in industry for wet or dry locations, run in tray or attached to building structure, above grade or buried in earth. A genericized trademark (Commonwealth English genericised trade mark), sometimes known as a generic trade mark, generic descriptor or proprietary eponym, is a trademark or brand name which has become synonymous with the general or formal term for a particular type of product or service, to the extent that it often... The General Electric Company, or GE, (NYSE: GE) is a multinational technology and services company. ...


Electrical power cables are often installed in raceways including electrical conduit, and cable trays, which may contain one or more conductors. Conduit may also be rigid or flexible, metallic or non-metallic, and differentiation from cable may require some investigation of the contents at their termination. By comparison, most conduits are arranged so that their contents may be "pulled" or removed from an opening in the conduit, whereas conductors in cables are bundled tightly within the jacket, etc, as a unit. Cables undergo many stresses when being installed, that of tension, and the insulation being crushed at the bends of the temporary pulleys or at the bends of the raceway. Lubrications are used in conduits ahead of the cable to provide less friction, but these must be compatible with the nonmetallic materials of the cable -- a froth of vegetable-oil soap and water is good. The AC component has little resistance to tension.


Flexible cables

Cables are somewhat flexible, and are packaged in rolls or coils -- larger sizes on reels. However, in applications requiring a cable to be moved repeatedly, a more flexible cable should be used. Small cables are called "cords". Flexible cords contain finer stranded conductors, rather than solid, and have insulation and sheathes that are engineered to withstand the forces of repeated flexing. Heavy duty flexible power cords such as feeding a mine face cutting machine are carefully engineered -- since their life is measurable in (6) weeks! See "Power cord" and "Extension cable" for further description of flexible power cables. Other types of flexible cable include twisted pair, extensible, coaxial, shielded, and communication cable. A mains cable (International English) or power cord (American English) is cable that temporarily connects an electrical appliance to an electrical power source. ... An extension cord (also known as a power extender or an extension lead) is a length of flexible electrical cable (flex) with a plug on one end and one or more sockets on the other end (usually of the same type as the plug). ... 25 Pair Color Code Chart 10BASE-T UTP Cable Twisted pair cabling is a common form of wiring in which two conductors are wound around each other for the purposes of cancelling out electromagnetic interference known as crosstalk. ... Coaxial cable is an electrical cable consisting of a round conducting wire, surrounded by an insulating spacer, surrounded by a cylindrical conducting sheath, and usually surrounded by a final insulating layer. ... A shielded cable has a conducting material in close contact with the outer surface of the insulation of an insulated cable. ...


See also


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Electrical wire is usually copper because of its excellent conductivity, but aluminium is sometimes used because it costs less.
Circuit integrity for cables is also established by using either inherently fire resistant cables, such as Mineral-insulated copper-clad cables, or by using boxes made of proprietary insulations, such as calcium silicate, vermiculite or perlite, intumescent and/or endothermic coatings or ceramic fibre or rockwool wraps for fireproofing purposes.
Electrical circuits that may have to be kept operational during an accidental building fire include, but are not limited to emergency power circuits, such as those that power exit signs in a building, power circuits for operating rooms in a hospital, or the wiring that connects control rooms and nuclear reactors.
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