A conductor’s size has a huge effect on a cable’s or application’s performance. When purchasing a wire or cable, it is important to understand the differences in sizes to ensure your application performs at its best.
In the United States, smaller conductors are measured using the American Wire Gauge (AWG). With the gauge system, the higher the number is, the smaller the cable will be. For larger wires, circular mils are used. MCM sizes, also called kcmils (kilo-circular mils), are for even larger cables. One MCM is equivalent to 1,000 circular mils.
For Britain and Canada, a system called the British Standard Wire Gauge (SWG) is the measurement system of choice. In other international countries, conductors are measured using their cross-section, which is given in square millimeters.
AWG: In the American Wire Gauge system, 36 AWG wire has a 0.0050-inch diameter. A 1000 (4/0) wire, has a .4600-inch diameter. There are also 39 gauge sizes in between. Although it seems like a strange system, it is designed so that the wire area approximately doubles for every three steps on the gauge scale.
For AWG-metric conversions for the most common sizes of wire, see the chart below.