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The Mystery of American Wire Gauge: What is the historical origin behind AWG?
American Wire Gauge (AWG) has been the standard wire gauge system in North America since 1857 and is widely used for diameter measurement of round, solid, non-magnetic electrical conductors. This standard is clearly defined in ASTM B 258 and provides a basic reference for the current carrying capacity of electrical conductors. Behind this seemingly technical specification, there is a little-known history.
The origins of AWG can be traced to the drawing process used to produce specific wire gauges. While the thinnest wires require multiple draws, thicker wires require less.
The development of AWG is undoubtedly a rationalization of the diverse wire gauge systems of the past. Early wire gauges were mostly set by manufacturers according to their own standards, which led to difficulty and inconvenience in wire selection. The standardized AWG system gives electricians and engineers a consistent basis for selecting appropriate cables. Although there are certain similarities between AWG and the Brown & Sharpe (B&S) thin plate specification system, the latter is mainly designed for thin plates, and applying B&S to electrical conductors is a misplaced usage.
AWG technical specifications
The AWG system is characterized by a tight correspondence between numbers and diameters: as the number of gauges increases, the diameter of the wire decreases logarithmically. This design is similar to other non-metric standards such as British Standard Wire Gauge (SWG), but AWG is significantly different from the metric standard of IEC 60228, which describes the cross-sectional area of a wire directly in millimeters squared (mm²).
The AWG table is based on a single solid circular conductor, while the AWG of stranded wire is determined based on the cross-sectional area of the equivalent solid conductor.
AWG standards define the relationship between different specifications. For example, 36 AWG is 0.005 inches in diameter, while 0000 AWG is 0.46 inches in diameter, a ratio between sizes of approximately 1:92. This difference is particularly important in practical electrical applications, where precise wire specifications are critical to electrical performance when producing printed circuit boards.
Common practical rules for AWG
In practical applications, there are also some common rules of thumb for AWG, such as: when the cross-sectional area of the wire doubles, the AWG specification will drop by 3 digits. This means that two 14 AWG wires of the same gauge have the same cross-sectional area as one 11 AWG wire, increasing the conductivity.
When the diameter of a wire doubles, the AWG specification drops by 6 digits because the change in diameter has a significant effect on the area of the wire.
The difference between AWG and stranded wire
AWG is not only applied to solid wire, but can also be used to describe the specifications of stranded wire. The AWG of a stranded wire represents the total cross-sectional diameter of the individual stranded conductors, but does not account for the gaps between them. Typically, these gaps account for approximately 25% of the conductor area, so the overall diameter of the stranded wire will be approximately 13% larger than solid wire of the same AWG. Therefore, correct AWG rules are crucial for designing and selecting appropriate wires.
Summary and reflection
The AWG system, with a history of more than 150 years, not only plays an extremely important role in the American electrical industry, but also further promotes the development and safe use of electronic products in terms of technical standardization. Through this system, electricians and engineers can not only quickly select the appropriate conductors, but also ensure the safety and efficiency of electrical installations. However, is this technical system still adequate to meet the current changing technical challenges and market demands?
