This app will calc the voltage and % dropped and give you the impedance of the wire based on the inputted values. Click the green letters to toggle input options (i.e custom voltage).Uses the 2008/2011 NEC values for impedance (AWG only). Be sure to input the appropriate temperature or the voltage drop will be very optimistic.This app also has the ability to measure the distance between two GPS points (only as accurate as your GPS)Get the pro version for more functionality!See About menu for more details.