Wire size is very important for the correct operation of electrical circuits. Selecting too small a gauge wire for an application will adversely effect the operation of the circuit. This will cause voltage drop and poor performance, or, in extreme cases, the cable will get hot enough to melt the insulation. Selecting too large a gauge increases costs and weight.
The resistance of a cable affects how much current it can carry. The resistance of a cable is determined by its length and its diameter.
The longer the cable and the smaller the diameter, the higher the resistance. The shorter the cable and the larger the diameter the lower the resistance.
To select the correct cable gauge for any given application it is best to refer to a cable chart. Manufacturers and standards bodies use cable gauge charts to define how much current each cable gauge can carry safely and effectively.
Over the years a number of different wire gauges have been used to determine application.
The primary wire gauges are the metric wire gauge and the American wire gauge or AWG.
For example, this 12 Volt circuit is designed for a maximum current flow of 10 Amps. Because of the installation design, the length of the cable used to wire the circuit needs to be approximately 20 feet or 7 meters in length, so using the AWG table as a reference we see that the correct gauge cable to use is 16AWG.
