Guidelines for Establishing Diagnostic Procedures for Live-Line Working of Nonceramic Insulators

The paper provides a review of the conditions that may be found on new nonceramic insulators (NCIs) and NCIs in service that will affect the live-line working of these insulators as well as conditions that are deemed to be inconsequential to live-line work. The most serious of these conditions are electrical tracking, vandal damage or erosion of the housing exposing the core, any of which may preclude the live-line working of NCIs. Various diagnostic tools and guidelines are reviewed indicating their strengths and limitations. Close-up visual inspection is by far the most dependable method of assessing the condition of NCIs as a necessary first step in contemplating live-line work. Various electrical test practices of NCIs are also reviewed as a means of ensuring safety in live-line change out or installation of NCIs.