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IEC 60228 is the International Electrotechnical Commission (IEC)'s international standard on conductors of insulated cables. As of 2023 [update] the current version is Third Edition 2004-11 [1] Among other things, it defines a set of standard wire cross-sectional areas:
In engineering applications, it is often most convenient to describe a wire in terms of its cross-section area, rather than its diameter, because the cross section is directly proportional to its strength and weight, and inversely proportional to its resistance. The cross-sectional area is also related to the maximum current that a metallic wire can carry safely.
This document is one considered fundamental in that it does not contain reference to any other standard.
The document describes several aspects of the conductors for electrical cables
This refers to the flexibility and thermal effects i.e temperature of a conductor.
The nominal (see below) cross-sectional area for standard conductors including the following:
The maximum permissible resistance per unit length (in ohms per kilometre – Ω/km) of each conductor size, class and type (both plain copper and metal coated)
This document and its precursors were created due to a need for a standard definition of cable conductor size. The main problem being that not all copper has the same resistivity value, so, for example, a 4 mm2 conductor from two different suppliers may have different resistance values. Instead this document describes conductors by their nominal size, determined by resistance rather than physical dimensions. This is a key distinction as it makes a standardized definition of conductors based solely on their electrical characteristics.
Almost all characteristics of conductors, resistance, current carrying capacity etc. are dependent on the physical dimensions of the conductor. However this document allows an easy reference whereby the standard conductor sizes and reference to physical dimensions are maintained but given an exact meaning in terms of the electrical characteristics of a conductor.
A wire is a flexible strand of metal.
In physics and electrical engineering, a conductor is an object or type of material that allows the flow of charge in one or more directions. Materials made of metal are common electrical conductors. The flow of negatively charged electrons generates electric current, positively charged holes, and positive or negative ions in some cases.
American Wire Gauge (AWG), also known as the Brown & Sharpe wire gauge, is a logarithmic stepped standardized wire gauge system used since 1857, predominantly in North America, for the diameters of round, solid, nonferrous, electrically conducting wire. Dimensions of the wires are given in ASTM standard B 258. The cross-sectional area of each gauge is an important factor for determining its current-carrying capacity.
In electric power distribution, a busbar is a metallic strip or bar, typically housed inside switchgear, panel boards, and busway enclosures for local high current power distribution. They are also used to connect high voltage equipment at electrical switchyards, and low voltage equipment in battery banks. They are generally uninsulated, and have sufficient stiffness to be supported in air by insulated pillars. These features allow sufficient cooling of the conductors, and the ability to tap in at various points without creating a new joint.
Electrical wiring is an electrical installation of cabling and associated devices such as switches, distribution boards, sockets, and light fittings in a structure.
A current transformer (CT) is a type of transformer that is used to reduce or multiply an alternating current (AC). It produces a current in its secondary which is proportional to the current in its primary.
A power cable is an electrical cable, an assembly of one or more electrical conductors, usually held together with an overall sheath. The assembly is used for transmission of electrical power. Power cables may be installed as permanent wiring within buildings, buried in the ground, run overhead, or exposed. Power cables that are bundled inside thermoplastic sheathing and that are intended to be run inside a building are known as NM-B.
Ampacity is a portmanteau for ampere capacity defined by National Electrical Codes, in some North American countries. Ampacity is defined as the maximum current, in amperes, that a conductor can carry continuously under the conditions of use without exceeding its temperature rating. Also described as current-carrying capacity.
The international standard IEC 60446Basic and safety principles for man-machine interface, marking and identification - Identification of equipment terminals, conductor terminations and conductors was a standard published by the International Electrotechnical Commission (IEC) that defined basic safety principles for identifying electrical conductors by colours or numerals, for example in electricity distribution wiring. The standard has been withdrawn; the fourth edition was merged in 2010 into the fifth edition of IEC 60445 along with the fourth edition, IEC 60445:2006.
Speaker wire is used to make the electrical connection between loudspeakers and audio amplifiers. Modern speaker wire consists of two or more electrical conductors individually insulated by plastic or, less commonly, rubber. The two wires are electrically identical, but are marked to identify the correct audio signal polarity. Most commonly, speaker wire comes in the form of zip cord.
Wire gauge is a measurement of wire diameter. This determines the amount of electric current the wire can safely carry, as well as its electrical resistance and weight.
A circular mil is a unit of area, equal to the area of a circle with a diameter of one mil. It corresponds to approximately 5.067×10−4 mm2. It is a unit intended for referring to the area of a wire with a circular cross section. As the definition of the unit contains π, it is easy to calculate area values in circular mils when the diameter in mils is known.
A thermoplastic-sheathed cable (TPS) consists of a toughened outer sheath of polyvinyl chloride (PVC) thermoplastic, covering one or more individual annealed copper conductors, themselves insulated with PVC. This type of wiring is commonly used for residential and light commercial construction in many countries. The flat version of the cable, with two insulated conductors and an uninsulated earth conductor, is referred to as twin and earth. In mainland Europe, a round equivalent is more common.
Magnet wire or enameled wire is a copper or aluminium wire coated with a very thin layer of insulation. It is used in the construction of transformers, inductors, motors, generators, speakers, hard disk head actuators, electromagnets, electric guitar pickups, and other applications that require tight coils of insulated wire.
Aluminium conductor steel-reinforced cable (ACSR) is a type of high-capacity, high-strength stranded conductor typically used in overhead power lines. The outer strands are high-purity aluminium, chosen for its good conductivity, low weight, low cost, resistance to corrosion and decent mechanical stress resistance. The centre strand is steel for additional strength to help support the weight of the conductor. Steel is of higher strength than aluminium which allows for increased mechanical tension to be applied on the conductor. Steel also has lower elastic and inelastic deformation due to mechanical loading as well as a lower coefficient of thermal expansion under current loading. These properties allow ACSR to sag significantly less than all-aluminium conductors. As per the International Electrotechnical Commission (IEC) and The CSA Group naming convention, ACSR is designated A1/S1A.
British Standard Wire Gauge is a unit for denoting wire size given by BS 3737:1964. It is also known as the Imperial Wire Gauge or British Standard Gauge. Use of SWG sizes has fallen greatly in popularity, but they are still used as a measure of thickness in guitar strings and some electrical wire. Cross sectional area in square millimetres is now the more usual size measurement for wires used in electrical installation cables. The current British Standard for metallic materials such as wire and sheet is BS 6722:1986, which is a solely metric standard.
In electrical power distribution, armoured cable usually means steel wire armoured cable (SWA) which is a hard-wearing power cable designed for the supply of mains electricity. It is one of a number of armoured electrical cables – which include 11 kV Cable and 33 kV Cable – and is found in underground systems, power networks and cable ducting.
Tri-rated cable is a high temperature, flame retardant electrical wire designed for use inside electrical equipment.
Copper has been used in electrical wiring since the invention of the electromagnet and the telegraph in the 1820s. The invention of the telephone in 1876 created further demand for copper wire as an electrical conductor.