In a Swedish financed research project efficient cable designs for WECs and TECs have been specified, designed and tested with focus on loads exposed to, reliability, lifetime and failure mechanisms. At the start of the project, the Swedish developers Waves4Power, Minesto and Corpower Ocean have specified their requirements on array cables at 1kV. NKT has then designed, optimised and fabricated cables that are then fulfilling these requirements in a cost-efficient manner. RISE has then performed extensive lab-testing and provided a test set-up for the in-field testing on Waves4Powers buoy in Runde, Norway. Chalmers University of Technology has based on the results, developed numerical models of the cable, the WEC and its environment, while RISE has worked on a reliability model based on the VMEA methodology. The results show that the derived cables are fulfilling the specifications and allow for a reliable transmission link for WECs and TECs. The methodologies used for measuring, modelling and testing have been found relevant and appropriate for optimising the cable design. The project was supported by the Swedish Energy Agency and has a duration of 2,5 years and will be finalised mid-2018.