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However, AWG is dissimilar to IEC 60228, the metric wire-size standard used in most parts of the world, based directly on the wire cross-section area (in square millimetres, mm 2). The AWG tables are for a single, solid and round conductor. The AWG of a stranded wire is determined by the cross-sectional area of the equivalent solid conductor.
The current British Standard for metallic materials including wire is BS 6722:1986, which is a solely metric standard, superseding 3737:1964, which used the SWG system. The IEC 60228 , used in most parts of the world, defines standard wire sizes based on their cross-sectional areas as expressed in mm 2 . [ 3 ]
For example, the United States National Electrical Code, Table 310.15(B)(16), specifies that up to three 8 AWG copper wires having a common insulating material (THWN) in a raceway, cable, or direct burial has an ampacity of 50 A when the ambient air is 30 °C, the conductor surface temperature allowed to be 75 °C. A single insulated conductor ...
J. H. Neher and M. H. McGrath were two electrical engineers who wrote a paper in 1957 about how to calculate the capacity of current (ampacity) of cables. [1] The paper described two-dimensional highly symmetric simplified calculations which have formed the basis for many cable application guidelines and regulations.
The formula to calculate the area in circular mil for any given AWG (American Wire Gauge) size is as follows.represents the area of number AWG. = (() /) For example, a number 12 gauge wire would use =:
The voltage and current phasors on the line are related by the characteristic impedance as: = (+) (+) = () where the subscripts (+) and (−) mark the separate constants for the waves traveling forward (+) and backward (−). The rightmost expression has a negative sign because the current in the backward wave has the opposite direction to ...
A standard wire gauge. The British Standard Wire Gauge, often referred to as the Standard Wire Gauge or simply SWG, is a unit used to denote wire gauge (size) as defined by BS 3737:1964, a standard that has since been withdrawn.
Therefore in a solid conductor like a wire, current tends to flow in a layer or annulus at the surface, and less current flows through the material near the center of the wire. Since less of the cross-sectional area of the wire is being used, the resistance of the wire is greater than it is for direct current (DC). The higher the frequency of ...