The risk of AC corrosion has always been linked in particular to the parallelisms of underground pipelines with HVAC lines, especially in those geographical areas where the morphology of the territory creates obligatory so-called "technological corridors", and therefore forces the coexistence of different services over long distances. More recently, the greater diffusion of AC-powered railway networks has further increased the AC interfering sources, while the use of more performing coatings on underground pipelines has on the one hand increased their insulation from the surrounding soil, and on the other has increased the risk of overprotection compared to old, less performing, or more degraded coatings. This paper, starting from a real case found in a gas distribution network in a European big city, will present the normative criteria to be used to keep the AC corrosion risk under control, and will highlight how precisely the simultaneous presence of cathodic overprotection may result in an autocatalytic cycle leading to accelerated AC corrosion, in which monitoring becomes essential in order to be able to carry out on time the appropriate corrective actions.