What is Available Fault Current?Available Fault Current DefinitionAvailable Fault Current (AFC) is defined as the maximum current available during a fault condition, also known as available short-circuit current.Importance of AFC MarkingAFC must be marked with a calculation date as per the 2011 NFPA 70: NEC section 110.24.Fault Current CalculationTo calculate fault current, use the system voltage, conductor constant, and length of the service entrance conductor. Find the system voltage (E_{L-L})