How Do You Calculate Power Wire Gauge Required?
Although electrical power (expressed in watts) is defined as current times voltage, the maximum power a specific gauge of copper wire can deliver to an appliance depends on both the length and diameter of the actual wire. Determine the desired length of the wire (expressed in kilometers). For example, 20 meters of wire is equal to 0.02 kilometers. Multiply this distance by 2. Look up the resistance per kilometer for that particular gauge of wire (see the “Resources” section below for a direct link to a complete chart). Multiply the value from Step 2 by the gauge’s resistance per kilometer (i.e. “ohms per km”) to calculate the “voltage drop” caused by the wire. Subtract the voltage drop from the voltage level of the electrical outlet you plan on using. Note: in the United States, the standard outlet supplies 120V. This newly-adjusted value represents the voltage that will actually reach the appliance on the other end of the wire. To calculate the maximum power transmission for the wire,
