Progress with polymeric insulators on British Rail

Polymeric insulators have been in use on British Rail (BR) overhead lines for 20 years. Their flexibility, small diameter and low mass make them attractive for use in areas such as section insulators, bridges and tunnels of tight clearance and in areas of vandalism. Some designs in the past have given problems, such as poor track resistance, poor coating adhesion, or notching of glass fibre rod, but after a long materials evaluation and with production to improved specifications, the polymeric insulator is now the most reliable insulator in service. In the last decade these polymeric materials have been introduced into other areas of railway equipment, and have performed well