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The use of nonceramic polymer insulators (NCIs) has grown, creating a very competitive market. In order to reduce the cycle time of design work and the cost of prototype testing, the use of electrical field stress analysis software can be applied. A commercially available software package is used to model insulators under a variety of applied voltages and contamination levels to establish relative electrical stresses. These stresses can be compared with designs that have been laboratory tested to verify an electrical performance improvement. The program was used to evaluate electrical stresses on insulators with different shed placements and profiles. Accelerated aging testing was conducted at EPRI (Electric Power Research Institute), and the data verifies the prediction of the computer model. Salt fog testing was conducted to determine the relationship between electrical performance and shed placement. The program was also used to evaluate electrical stresses on insulators with different corona ring designs. Testing was conducted in laboratories, and the data once again supports the predictions of the computer model.