ABSTRACT
To the average user the only important part of the electricity service is the outlets at which he gets his electricity. To the engineer concerned with designing or installing the service, the system of cables which links these outlets to each other and to the supply coming in to the building is just as important and perhaps even more so. In practice, the electrical service is a complete interdependent system and the practical engineer thinks of it as a whole, but, as with the teaching of any subject, one has to break it down into parts in order to explain it in an orderly fashion which will make sense to a student with no previous knowledge of the subject.
