An arc fault circuit interrupter comprising: separable contacts; a neutral conductor; an operating mechanism structured to open and close said separable contacts; at least one current sensor (8,50,52) structured to sense current flowing through said separable contacts and output a sensed current value; and a processor comprising a first routine structured to provide parallel arc fault detection, a second routine structured to provide series arc fault detection, and a third routine structured to enable said first routine and disable said second routine when said sensed current value is greater than a predetermined value and to enable said second routine and disable said first routine when said sensed current value is less than said predetermined value, wherein said processor is structured to cooperate with one of said at least one current sensor to determine and store a plurality of peak values of the sensed current value for a plurality of half-cycles of said current flowing through said separable contacts; wherein said first routine is further structured to determine both of: (a) whether a first predetermined plurality of said half-cycles of said current occur in succession and correspond to a non-unity power factor, and to responsively inhibit said parallel arc fault detection for a first predetermined time, and (b) whether a second predetermined plurality of said half-cycles of said current occur in succession and each of said second predetermined plurality of said half-cycles of said current has a smaller peak amplitude than that of an immediately preceding one of said half-cycles of said current of like polarity or of differing polarity, and to responsively inhibit said parallel arc fault detection for a second predetermined time; and wherein said processor is further structured to determine that said parallel arc fault detection is not inhibited for both of said first predetermined time and said second predetermined time, and to responsively indicate that at least one of said half-cycles of said current having a peak amplitude greater than or equal to a predetermined amount is a parallel arc. separable contacts; a neutral conductor; an operating mechanism structured to open and close said separable contacts; at least one current sensor (8,50,52) structured to sense current flowing through said separable contacts and output a sensed current value; and a processor comprising a first routine structured to provide parallel arc fault detection, a second routine structured to provide series arc fault detection, and a third routine structured to enable said first routine and disable said second routine when said sensed current value is greater than a predetermined value and to enable said second routine and disable said first routine when said sensed current value is less than said predetermined value, wherein said processor is structured to cooperate with one of said at least one current sensor to determine and store a plurality of peak values of the sensed current value for a plurality of half-cycles of said current flowing through said separable contacts; wherein said first routine is further structured to determine both of: (a) whether a first predetermined plurality of said half-cycles of said current occur in succession and correspond to a non-unity power factor, and to responsively inhibit said parallel arc fault detection for a first predetermined time, and (b) whether a second predetermined plurality of said half-cycles of said current occur in succession and each of said second predetermined plurality of said half-cycles of said current has a smaller peak amplitude than that of an immediately preceding one of said half-cycles of said current of like polarity or of differing polarity, and to responsively inhibit said parallel arc fault detection for a second predetermined time; and wherein said processor is further structured to determine that said parallel arc fault detection is not inhibited for both of said first predetermined time and said second predetermined time, and to responsively indicate that at least one of said half-cycles of said current having a peak amplitude greater than or equal to a predetermined amount is a parallel arc.