Superconducting cables have been built and tested for voltages larger than 100 kV, currents up to 5 kA and a length of up to 1 km. Within long term field tests, superconducting power cables have shown that they can fulfill all technical and operational requirements. This resulted in an increased interest for more applications and in contrast to the voltage and current design parameters, the cooling design parameters of a superconducting cable depend mainly on the length of the cable and the heat input. These parameters have to be adapted to each cable to fulfil the specification. This presentation gives an overview on cable specifications and requirements and points out specific cooling requirements. For two different examples of a medium and high voltage cable, design options are presented and discussed. It can be seen that the different loss contributions differ very much between medium and high voltage cables and that for example the interconnection between specification and maximum length before re-cooling needs a careful investigation. Finally, a design procedure is proposed that considers main specification and cooling requirements.