This article describes online monitor of the pollution severity of heavily polluted insulators of power lines in a polluted atmosphere. The suggested monitor works by sensing and analyzing the leakage current bursts. If these bursts are judged by the monitor as corresponding to a potentially dangerous level the monitor transmits an alarm signal to the service crew so that they would clean the insulators of the line or substations in time before a sudden line outage occurs, with entailed excessive expense loss of power supply and annoyance to customer. Line insulator cleaning is thus carried out, when necessary, which adds to the economy of the power system operation. The suggested monitor based on the artificial neural networks, which are fed by the leakage current bursts, and also the environmental conditions collected from the field. The monitor gives a good operation performance when tested in practical simulated conditions. The hardware schematic is presented to act the function of online monitoring system.