This is the only comprehensive book on the subject of gas insulated transmission lines (GIL). Written by renowned experts with both academic and industry experience, it covers the design, construction, operation, maintenance and testing of GILs. It includes experience in European and Asian countries and discusses developing strategies to substitute other gases and mixtures to reduce the greenhouse impact of the current use of sulphur hexafluoride. The book is intended for designers and electrical energy systems operators of electrical energy systems world wide, particularly in or near urban areas.