extension cord vs relocatable power tap

extension cord

noun
  • An electrical cord with a plug one end, and a single socket or a multi-port socket at the other end, used for powering one or more devices at a distance, too far from the wall outlet to be reached by the normal cords of the device or devices. 

relocatable power tap

noun
  • A multi-socket power cord that can be used to channel electricity from a single socket. 

How often have the words extension cord and relocatable power tap occurred in a corpus of books? (source: Google Ngram Viewer )