screw anchor vs wall plug

screw anchor

noun
  • A fixing that allows screws to be fitted into masonry walls; called a wall plug in UK English. 

wall plug

noun
  • A fixing that allows screws to be fitted into masonry walls, a dowel or screw anchor. 

  • An electric socket. 

How often have the words screw anchor and wall plug occurred in a corpus of books? (source: Google Ngram Viewer )