<p>A system for testing an arcing fault detection System in an electrical distribution network having a line conductor carrying an electrical signal between a power source and a load, the arcing fault detection system including a sensor coupled to the line conductor for monitoring the electrical signal and generating a sensor signal representing the electrical signal, the arcing fault detection system generating an arc-indicative signal in response to the sensor signal having characteristics indicative of an arcing fault. The testing system couples the sensor to a test line simultaneously with the line conductor and periodically produces a test signal on the test line. The sensor simultaneously monitors the test signal and the electrical signal and produces a sensor signal representing both the test signal and the electrical signal when the test signal is present on the test line. The arcing fault detection system generates an arc-indicative signal in response to the sensor signal associated with either the test line or line conductor having characteristics indicative of an arcing fault. A diagnostic test integrator evaluates the status conditions of the test signal and the arc-indicative signal and generates a trip signal to trigger the interruption of the electrical signal in response to certain status conditions of the test signal and the arc-indicative signal. <IMAGE></p>