cable tray vs water carrier

cable tray

noun
  • A rigid structure to support electric cables; a type of raceway, normally having the appearance of a ladder and open at the top to facilitate changes. 

water carrier

noun
  • An arrangement of wires on which a bucket of water, raised from a well, etc., may be conveyed wherever required, as to a house. 

  • A pipe or tube that conveys water. 

  • A person who carries water from a spring or well, especially in antiquity and pre-modern era when it was a common job. 

  • A transportation ship that is water-based. 

  • An individual doing simple, ordinary work, usually in opposition to somebody considered more valuable. 

  • Aquarius, or a symbol for it. 

  • A domestique. 

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