electrical energy vs mains

electrical energy

noun
  • Energy made available for consumption or consumed in the form of electricity or electric power; electricity. 

mains

noun
  • The domestic electrical power supply. 

  • The pipes of a centralized water supply that transport the water to individual buildings. 

  • The farm attached to a mansion house. 

  • The main course of a meal. 

How often have the words electrical energy and mains occurred in a corpus of books? (source: Google Ngram Viewer )