This book presents an innovative concept for designing a 400 kV double circuit composite tower. The major challenges encountered by the authors in the electrical design process of the composite tower are addressed. They concern material selection for the full composite cross-arm core, electrical insulation of the cross-arm, electrical dimensioning of the full composite tower, lightning shielding performance and failure of the full composite tower. The electric field performance of the tower’s insulation has been investigated theoretically by using finite element method and experimentally by testing different fiber reinforced polymers as candidates. The book reports in detail those finite element simulations and tests, together with the authors’ recommendations on the most suitable materials and manufacturing process as well as conductor clamp designs for the cross-arm. Another important issue of the full composite tower, which concerns the environmental aspects of the full composite tower, has also been evaluated. This book offers a timely reference guide on a highly innovative topic, addressing researchers working on power transmission system both in industry and academia.