An arc fault protective wiring device disposed in an electrical distribution system, the device comprising: a plurality of line terminals (12, 14) comprising a line-side phase terminal and a line-side neutral terminal; a plurality of load terminals (16, 18) comprising a load-side phase terminal and a load-side neutral terminal; a line conductor electrically coupling the line-side phase terminal to the load-side phase terminal; a neutral conductor electrically coupling the line-side neutral terminal to the load-side neutral terminal; a pulse frequency digitizer, the pulse frequency digitizer being configured to receive a plurality of pulses, each pulse being representative of an instance that a derivative of current through the conductor (20, 22) exceeds a first predetermined threshold, the pulse frequency digitizer further being configured to produce a digital signal, the digital signal being representative of the instances at which a frequency of the plurality of pulses exceeds a second predetermined threshold; and at least one processor configured to determine whether an arc is occurring based, at least in part, on the digital signal, the device being characterised by further comprising a shunt amplifier having a first input terminal, the first input terminal being connected at a first point along the neutral conductor between the line-side neutral terminal and the load-side neutral terminal, the first point being positioned such that a detectable voltage, proportional to current flowing through the neutral conductor and as a result of a resistance of the neutral conductor, is present, wherein the shunt amplifier is configured to output a shunt signal having a voltage value proportional to the current through the neutral conductor, wherein the at least one processor is configured to determine whether an arc is occurring based also, at least in part, on the shunt signal and to trigger the circuit interrupter to electrically decouple at least one of the plurality of line terminals (12, 14) from the at least one of the plurality of load terminals (16, 18) if it is determined that an arc is occurring. a plurality of line terminals (12, 14) comprising a line-side phase terminal and a line-side neutral terminal; a plurality of load terminals (16, 18) comprising a load-side phase terminal and a load-side neutral terminal; a line conductor electrically coupling the line-side phase terminal to the load-side phase terminal; a neutral conductor electrically coupling the line-side neutral terminal to the load-side neutral terminal; a pulse frequency digitizer, the pulse frequency digitizer being configured to receive a plurality of pulses, each pulse being representative of an instance that a derivative of current through the conductor (20, 22) exceeds a first predetermined threshold, the pulse frequency digitizer further being configured to produce a digital signal, the digital signal being representative of the instances at which a frequency of the plurality of pulses exceeds a second predetermined threshold; and at least one processor configured to determine whether an arc is occurring based, at least in part, on the digital signal, the device being characterised by further comprising a shunt amplifier having a first input terminal, the first input terminal being connected at a first point along the neutral conductor between the line-side neutral terminal and the load-side neutral terminal, the first point being positioned such that a detectable voltage, proportional to current flowing through the neutral conductor and as a result of a resistance of the neutral conductor, is present, wherein the shunt amplifier is configured to output a shunt signal having a voltage value proportional to the current through the neutral conductor, wherein the at least one processor is configured to determine whether an arc is occurring based also, at least in part, on the shunt signal and to trigger the circuit interrupter to electrically decouple at least one of the plurality of line terminals (12, 14) from the at least one of the plurality of load terminals (16, 18) if it is determined that an arc is occurring.