A great tool for electrical engineers and electricians.This app will calculate a fault:Over a lineThrough a XFMR The bracing de-rate factor for a utility XR ratio. Where length is inputted you can use your GPS from your phone to get an approximate distance (only as accurate as the GPS in your phone).The calculations use the 2008/2011 NEC codeSee the About menu for additional functionsGet this app plus Voltage Drop, Wire Ampacity and Box/Conduit fill with Electric Pro