This guide assists in application to engineers for the preparation of a design criteria document used for overhead transmission lines. A design criteria documents the data and assumptions used; the sources of the data and assumptions; the conventions, standards, guides, and design manuals used; and the design method(s) used in the design of the transmission line. The guide offers a comprehensive table of contents of the important criteria that should be taken into consideration in the design of transmission lines. The guide discusses the various criteria. The guide does not recommend criteria values, as would a design manual, but lists and discusses the importance of the criteria. The design engineer must determine the values to use based on the location, ambient conditions, and importance of the line.