Methods of detecting arc faults characterized by consecutive periods of arcing

An apparatus (100) and method for detecting electrical arc faults that has reduced susceptibility to nuisance tripping. The apparatus includes a current sensor (101), an input sense circuit (102), an arcing sense circuit (104), a power supply (106), a tripping circuit (108), a processing unit (112), and an electromechanical interface (117). The processing unit measures multiple voltage levels provided by the arcing sense circuit during a specified number of consecutive time periods. Next, the processing unit determines the number of consecutive time periods during which the voltage levels exceeded a specified minimum value, take on successively lower or higher values, or fall outside a predetermined normal range of values. Based upon the results of this determination, the processing unit either trips the electromechanical interface to interrupt power to a load, or inhibits tripping of the electromechanical interface, thereby reducing the occurrence of nuisance tripping.