The Size of Conductors
There are several systems used to define the size of conductors. Some of the more common ones are the American Wire Gauge (AWG), British Standard Wire Gauge (Imperial) and Metric Wire Gauge. The one commonly used in the United States is the American Wire Gauge (AWG); previously known as the Brown & Sharpe Wire Gauge. The AWG system consists of even numbered sizes ranging from 4/0 or No. 0000 (the largest) down to No. 40 (the smallest). In many of the AWG charts used today, the smallest size is #56 AWG. Gauges 45 through 56 were added in 1961 although the system itself was originally developed in 1912. The AWG system is based upon two gauges that were exact whole numbers with all intermediate gauges calculated from these two fixed values in terms of a geometric progression.
Simple AWM system tools to include:
- An increase of three gauge sizes (36 to 33) approximately doubles the cross section and weight and reduces the resistance by half.
- An increase of six gauge sizes (36 to 30) approximately doubles the diameter.
- An increase of ten gauge sizes (36 to 26) multiplies the cross section and weight by approximately ten and divides the resistance by ten.
AWG gauges are also used to describe stranded wire. Stranded wires are specified with three numbers, the overall AWG size, the number of strands, and the AWG size of a strand. The number of strands and the AWG of a strand are separated by a slash. For example, a 22 AWG 7/30 stranded wire is a 22 AWG wire made from seven strands of 30 AWG wire.