There are many types of wire size calculators, and they are available for free on the Web. The following is an overview of their functions and how they are used. These are general guidelines only. Refer to the site for more complete instructions.
How to Use the Calculator
The circuit phase will be single phase or three phases. Input the entire circuit amperage. Put in half of the entire circuit length. Example: a 120 volt, single phase, 144 ft (total 288 ft), copper wire with 10 amperage will have a wire 10 awg in size. When using a wire size calculator, it is important to check the electrical codes in your area.
How to Calculate Volt Drop
Get the wire dimensions by utilizing a wire gauge and the multimeter. Multiply the load amps by 0.2. Assuming the wire load is 16 amps, the formula is 16 x 0.2 = 3.2. If the size is 8 AWG, the formula will be 8 – 10 = -2. The result is 1.26 E (-2).
Now you have to multiply both results to get the drop over 100 ft: 3.2 x 0.0126 = 0.04032. Now you have to divide entire wire run figure by 100. Assuming the run is 300 ft, the formula is: 300 / 100 = 3. Now multiply this figure by the volt drop over 100 ft. The result would be 3 x 0.04032 = 0.12096.
Figuring out Wire Size and Circuit Breakers
Get the wattage of every appliance hooked to the circuit. The wattage is specified on the back or under the appliance. If it is not in the appliance, check the website of the manufacturer.
Now combine the wattage of all the appliances; you do not need a wire size calculator for this. An ordinary calculator will do. When you get a figure, divide this by the circuit voltage. This will be the minimum amp for the whole circuit.
Now multiply this figure by 1.25. This will help you determine what amperage is needed. For safety reasons, the circuit amperage capacity must be 25% more than the theoretical load. Now you can go to the Web and get a wire gauge chart. This will help you determine the wire needed for the circuit amp rating.
Size of Stranded Wires
Get a scientific calculator. Subtract the AWG from 36 and divide the figure by 39. Use X to Y power to get 92. Multiply this by 0.005. You can also use a conversion chart from the Web. One you can use the chart from the U. S. Department of Energy’s Sector 7 at Argonne National Laboratories.
Using a wire size calculator is helpful not just for engineers, but also for home owners. From wiring speakers to figuring out the voltage drop, knowing how to use these calculators will come in handy.