Detection and location of electrical faults in a network of metal structures which can receive electric cables and allow return of current by the cables. The reflectometry-based method involves injecting a probe signal into a cable coupled to the structures and analyzing the signal reflected by the anomalies. A conductive element is provided for carrying the probe signal at a constant distance from each structure. In one aspect, an insulated conductive element is arranged inside the metal structure and is built into a longitudinal groove in a surface for receiving a longitudinal plastic holder wedged into the structure. The reflected signal from the conductive element is compared to a threshold above which an anomaly is detected, and the anomaly is located by topological correlation. The invention is useful for airplane raceways having a composite skin.