I think you are confused about your subpanel. It is possible to run a 240 volt only subpanel from a main panel in the United States. That would require two hot leads plus a ground. If you wired a subpanel as 240 volt only, you would not be able to get 120 volt circuits from such a panel.
You are wiring a 120/240 volts panel, which requires two hots, a neutral, plus a ground. The voltage drop is a function of the number of amps you draw, the type of wire (copper or aluminum), the size of wire, and the total distance (to and from the subpanel). In your case, the total distance is 420 feet, however the calculator I used requires one way distance (it doubles the distance internally). If you draw the maximum amperage (60 amps in your case), and you use Al #4 wire, your voltage drop is going to be about 10 volts, which is a little over 4 percent, which is probably fine. To verify the drop, check out this website http://www.calculator.net.
You should get the same result no matter what voltage calculator you use, since all of the calculators use the same formula, namely voltage drop =
I * R, where I is the current and R is the resistance of the wire. What can be confusing is that the voltage loss requires you to use the TOTAL round trip distance, since you lose voltage in both directions. Some calculators do not make it clear whether you should use the one way distance (the calculator doubles the distance internally) or the round trip distance.
If you want to verify, use the actual resistance per foot for aluminum wire. This website gives you good information on wire resistance per foot for a variety of materials http://www.cvel.clemson.edu/emc/calculators/Resistance_Calculator/wire.html. Note that for #4 Al wire, 60 Hertz, 420 feet, total resistance is 0.171 ohms, so the loss is 60 * .171 = 10.3 volts, which is the same result as the on line voltage drop calculator.
Your percentage drop is calculated based on the nominal voltage of the run, in your case 240 volts. The actual voltage drop is the same no matter what the voltage, but of course the higher the nominal voltage the lower the percentage drop.
You are wiring a 120/240 volts panel, which requires two hots, a neutral, plus a ground. The voltage drop is a function of the number of amps you draw, the type of wire (copper or aluminum), the size of wire, and the total distance (to and from the subpanel). In your case, the total distance is 420 feet, however the calculator I used requires one way distance (it doubles the distance internally). If you draw the maximum amperage (60 amps in your case), and you use Al #4 wire, your voltage drop is going to be about 10 volts, which is a little over 4 percent, which is probably fine. To verify the drop, check out this website http://www.calculator.net.
You should get the same result no matter what voltage calculator you use, since all of the calculators use the same formula, namely voltage drop =
I * R, where I is the current and R is the resistance of the wire. What can be confusing is that the voltage loss requires you to use the TOTAL round trip distance, since you lose voltage in both directions. Some calculators do not make it clear whether you should use the one way distance (the calculator doubles the distance internally) or the round trip distance.
If you want to verify, use the actual resistance per foot for aluminum wire. This website gives you good information on wire resistance per foot for a variety of materials http://www.cvel.clemson.edu/emc/calculators/Resistance_Calculator/wire.html. Note that for #4 Al wire, 60 Hertz, 420 feet, total resistance is 0.171 ohms, so the loss is 60 * .171 = 10.3 volts, which is the same result as the on line voltage drop calculator.
Your percentage drop is calculated based on the nominal voltage of the run, in your case 240 volts. The actual voltage drop is the same no matter what the voltage, but of course the higher the nominal voltage the lower the percentage drop.
