A direct current feeder protection system includes six conductors, four current sensors sensing four currents flowing in four of the conductors, four circuit interrupters interrupting currents flowing in the four conductors, and a processor cooperating with the current sensors to input four sensed currents, and to output a number of commands to the circuit interrupters. The processor includes a routine detecting a number of: a directional current fault of the sensed currents, a differential current fault of the sensed first and third currents or the sensed second and fourth currents, and a residual current fault of the sensed first and second currents or the sensed third and fourth currents, and to responsively output the commands. The first, fifth and third conductors are electrically connected in series with two of the circuit interrupters, and the second, sixth and fourth conductors are electrically connected in series with the other circuit interrupters.