The present study shows the effects of room temperature vulcanizing (RTV) silicone rubber high voltage insulator coatings on the discharge characteristics of a cap-and-pin type suspension glass insulator. The study covers both laboratory investigations and 3D electric field analysis, considering the coated and uncoated glass insulators. An ultraviolet corona camera is used to detect the location of the discharges, and a partial discharge test system is used to obtain the discharge patterns and pulse magnitudes. The experimental work is only conducted for 50 Hz power frequency voltage. In addition to the laboratory investigations, 3D electrostatic field analysis is performed to determine how the RTV coatings on the glass insulators affect the field distributions.