Abstract: A high performance, high voltage electrical insulator, for use at greater than 15 Kv in wet, contaminated conditions, is designed to give a minimum surface area while maintaining a low leakage current by specifying the ratios of shed diameter to shed pitch, leakage distance between support fittings to the straight line distance between support fittings, and the shed diameter to the support rod diameter. Through the use of specified silicone elastomeric compositions, or through the use of silicone compositions meeting specified electrical properties, an insulator meeting the design specifications is shown to be a useful high voltage insulator.