A power cable includes a conductor surrounded by one or more layers. At least one of the layers can include a polymer composition having an electric conductivity of 0.50×10−15 S/m or less when measured according to DC conductivity method using a tape sample. The polymer composition can include a polyolefin which is obtainable by a high pressure polymerization process. This process includes: compressing one or more monomers under pressure in a compressor, in which a compressor lubricant, such as mineral oil is used for lubrication; polymerizing a monomer optionally together with one or more comonomers in a polymerization zone; and separating the obtained polyolefin from the unreacted products and recovering the separated polyolefin in a recovery zone.