A Review of Current Wind Load Provisions for Transmission Pole Structures

Most utility companies in the U.S. use the National Electrical Safety Code (NESC) provisions to determine loads on transmission pole structures. Although several other standards for the calculation of wind loads on non-utility poles do exist, a major national standard that forms the basis of most other standards and is adopted by the building codes is ASCE 7-95 Minimum Design Loads for Buildings and Other Structures. A comparative review is made in this paper of the wind pressure calculated using both NESC and ASCE standards with the main objective of determining differences between those standards and the significant parameters affecting wind load calculations. The adequacy of the current NESC provisions for extreme wind loads will be discussed. The results should provide added insight into the differences between the two standards and may thus be of interest to the committee that is currently revising the ASCE 74 Guidelines for Electrical Transmission Line Structural Loading (under development).