Mechanical Load Limits for High voltage Insulators

High voltage insulators to satisfy overhead line load and strength requirements are currently selected based on their strength limit resistance. Most line components though are selected according to Load Resistance Factor Design (LRFD) in the 2012 edition of the NESC. To accommodate LRFD for insulators, service limit resistances for ceramic and composite insulators must be determined and related to the rated strengths as given in current ANSI C29 Standards for insulators. Converting insulator rated strengths to service limit resistances will be described and suggestions for assigning strengths and strength factors for insulators for inclusion in future NESC editions will be discussed.