Specifies the loading and strength requirements of overhead lines derived from reliability based design principles. The requirements apply to lines of 45 kV and above, but they can also be applied to lines with a lower nominal voltage. The design criteria apply to new lines, however many concepts can be used to address the reliability requirements for refurbishment and uprating of existing lines. Detailed design of line components such as towers, foundations, conductors or insulators are not covered in this document.