Non-ceramic insulators with polymer weather sheds were evaluated for applications in contaminated environments. Insulator design, material properties and construction of the weather shed component are discussed in terms of the effects of leakage current and erosion that accompany the deposition of contaminants and moisture. The deterioration of the EPR weather shed surfaces after outdoor exposure is of concern as the 60-Hz strength is decreased. The tests also confirm that radial joints formed by individual weather sheds are potential weak points of the insulator. The use of corona rings to alleviate damaging discharges between the metal fittings and the weather shed material is recommended for voltages as low as 230 kV