This book covers structural and foundation systems used in high-voltage transmission lines, conductors, insulators, hardware and component assembly. Furthermore, this text provides the essential fundamentals of transmission line design. It is a good blend of fundamental theory with practical design guidelines for overhead transmission lines, providing the basic groundwork for students as well as practicing power engineers, with material generally not found in one convenient book. Featuring design problems with solutions for students, the book is aimed at students, practicing engineers, researchers and academics. It contains beneficial information for those involved in the design and maintenance of transmission line structures and foundations. For those in academia, it will be an adequate textbook/design guide for graduate-level courses on the topic. Engineers and managers at utilities and electrical corporations will find the book to be a useful reference at work. This book presents the current state of electrical technology applied to the calculation and design of high voltage power lines, both aerial and underground, by means of an original approach based on the simple exposure of theoretical bases that allow the reader to apply them in the subsequent resolution of numerous real engineering examples. The examples in each chapter are developed in detail and have been selected in order to address the diversity of electrical and mechanical calculations required by the design of high voltage power lines. The book consists of chapters dedicated to the electrical design of lines, mechanical calculation of conductors, supports and foundations, design of grounding facilities and calculation of underground lines. There is no other book that gathers, in such a detailed way and with a focus eminently practical, all aspects related to the design of high voltage lines.