Voltage Drop Calculator

Length of run (feet)
Total Amps draw
Line Voltage
Wire Guage:
Wire Type:
voltage drop
% voltage drop

* Formula: (K * P * Length of wire in feet*Current in amps) / Wire area in circular mils
K= Specific resistivity in ohm- circular mils/foot
P= phase constant = 2 for 1ph, 1.732 for 3ph...default setting is for single phase.
The 10 Ga. wire run to the barn is 450 feet. 240 volts. The radial arm saw can be wired for 120 or 240 volts. At 120V it draws 13 Amps, at 240V it pulls 6.5 Amps. What I've read says to keep voltage drop below 2%.

By running 120V @ 13A I get a 12 volt drop or 10%...way too much. Wired for 240V I only draw 6.5 Amps. When I plug that into the formula, voltage drop is only 6 volts or 2.5%...sure looks better on paper.