Inspection of butyl rubber insulators on the Lea Valley line on 12 August 1973 (TM-ETR-11)

Tracking has occurred on butyl rubber covered glass-fibre under-bridge support arras on the Lea Valley line on Eastern Region. Greasing of the insulator surfaces with a silicone grease is being used as a palliative until new insulating materials have been evaluated. Greasing of all insulators took place during the winter...