At the end of this activity, students should be able to: û state the advantages and disadvantages of batteries and mains as power supplies. û describe the structure of a household electric mains. û explain why circuit breakers are used. û state the purpose of the third wire in a cable of certain devices. û describe how a residual current circuit breaker is used. û explain how three-phase current is separated for use in different apartments.

Originally released by Learnetic, 2016.