New NESC Extreme Ice Loading

Abstract

This paper deals with the effects of the National Electrical Safety Code (NESC)-2007 extreme ice with concurrent wind loading conditions, a new loading condition for the design of electric utility structures, hardware, and conductors. This paper provides answers to some of the questions that may be in the minds of utility engineers involved in the design of transmission line structures by comparing the effects of the new extreme ice loading condition with those of the existing NESC weather-related loading conditions. This study evaluates whether structures designed on the basis of the NESC district loading conditions or extreme wind loading conditions could sustain loads resulting from the new extreme ice loading condition and identifies the regions of the United States where the extreme ice loading conditions would not likely control the design of transmission line structures. The new NESC extreme ice loading condition is also compared with the ASCE Std7-05 ice and wind loadings for other structures.