Over here, PME (MEN or TN-C-S) in the past was confined to those rural areas where it was difficult to obtain a satisfactorily low reistance value with a ground rod. Each PME distribution system required consent from the Secretary of State for Energy. Thus the majority of rural areas with overhead distribution had homes where the ground rod was the sole method of earthing (TT system), and the ELCB was therefore very common.
PME has only really come into much more widespread use over the last 20 years or so.
Urban areas always had TN-S systems with the cable armor acting as a separate fault path right back to the transformer, so the ELCB was pretty much a rural device.
