The purpose of this interactive online course is to teach the basic principles of operation of pad-mounted transformers and switchgear, the types of equipment that are in common use, and how they are connected. The course also presents the basic principles of pad-mounted transformer and switchgear inspection and troubleshooting and shows an example of how to detect a problem with one leg of a three-phase transformer. At the conclusion of this course, participants should be able to state how pad-mounted transformers and switchgear are used and to describe how they are connected. They should be able to recognize and identify commonly used types of pad-mounted transformers and switchgear. They should also be able to inspect pad-mounted transformers and switchgear, and they should be able to detect a problem with one leg of a three-phase transformer.