A leakage current monitor was developed to measure and register the leakage current on the surface of ceramic line post insulators. Along with the leakage current, the ambient relative humidity and temperature were also measured and registered in insulators installed in urban and rural areas. The paper shows the results of these variables measurement and a correlation study among them. Main conclusions are that the leakage current is strongly dependent on ambient humidity. In polluted insulators the leakage current presents rather a random behavior, with lower dependency on the humidity.
