power cable vs power line

power cable

noun
  • An insulated cable which carries electrical current. 

power line

noun
  • An electrical wire, cable or conduit, suspended in air by utility poles or transmission towers, or buried underground, used for the carrying of electricity either from a power source such as a generating station to a substation, or from a substation to a building such as a plant, commercial building or a home. 

How often have the words power cable and power line occurred in a corpus of books? (source: Google Ngram Viewer )