cable tray vs sheath

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. 

sheath

noun
  • The insulating outer cover of an electrical cable. 

  • The base of a leaf when sheathing or investing a branch or stem, as in grasses. 

  • A holster for a sword; a scabbard. 

  • A condom. 

  • The foreskin of certain animals (for example, dogs and horses). 

  • A tight-fitting dress. 

  • Anything that has a similar shape to a scabbard that is used to hold an object that is longer than it is wide. 

  • One of the elytra of an insect. 

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