The use of electricity, especially at common line voltages, is inherently dangerous. When used haphazardly, electricity can lead to electrocution or fire. This danger is what led to the development of the National Electrical Code® (NEC®), and it is what keeps Underwriter''s Laboratories in business. The first real requirement of the NEC is that all work must be done 'in a neat and workmanlike manner.' This means that the installer must be alert, concerned, and well informed. It is critical that you, as the installer of potentially dangerous equipment, maintain a concern for the people who will be operating the systems you install.
This 1-hour interactive online course course covers the basic rules of electricity and electronics. It contains enough detail to help you through almost any difficulty that faces you, short of playing electronic design engineer. It will also serve you well as a review text from time to time.