American Wire Gauge (AWG) is the U.S. standardized wire gauge system used to note the diameter of rounded, non-ferrous electrical wiring. As a general rule of thumb, for every 6 gauge decrease, the wire diameter doubles, and every 3 gauge decrease doubles the cross-sectional area. The table below illustrates the conversion of AWG to MM2 (or MM2 to AWG) for easy conversion of wire gauge to mm2.
|Wire Size Conversion Chart - American Wire Gauge to square millimeters|
Since 1857, wire gauge to MM2 made determining a wire’s current-carrying ratings easier. AWG is determined by first figuring out the radius of a wire squared, time pi. Oftentimes the term “circular mil” is used. Circular mil is the area of a 1/1000 (or 1 mil) diameter circle. Such measurements are made on only the wire and not on the wire’s jacketing or insulation. In fact, jacketing and insulation are not size determining factors of AWG. As a general rule of thumb, the higher the AWG number, the smaller (or thinner) the wire will be.
Since smaller gauge sizes are more durable and flexible, it’s common practice to use them with higher AWG numbers when stranding conductors for bending or vibration applications. While you can tightly wind or braid wires, there will always be some type of small gap between the strands. This is why AWG wires are always slightly bigger in diameter than solid wire.
AWG is also related to resistance. Resistance acts upon both a direct current and alternating current to create a “skin effect.” Simply put, as a signal frequency increases, the current flow of the wire concentrates toward the skin (outside) of the conductor. If you measured the resistance at different frequencies, you’d find that the resistance increases as frequency increases. Essentially, a thicker wire will have less resistance and carry more voltage at a longer distance.
Choosing a wire size will depend on the gauge and length you need. To determine the gauge wire you need, consider what carrying capacity and amount of current the wire needs to conduct to work for your application. Now consider the distance. The distance your wire needs to go can impact the gauge size you need. The longer the wire, the more voltage you can lose through resistance and heat. One way to counteract voltage drop is by increasing the wire gauge, which increases your amperage capacity, allowing you to pump more amperage through and ultimately, give you enough electricity for the intended application.