CHAPTER Electricity 12 A real understanding of electricity enables the technician to troubleshoot intelligently, and is an essential part of set safety--for you, and for all those you work with. In this chapter, we start with the principles of how electricity works. We want to build a mental picture of how electrical forces behave; how current, voltage, power, and resistance are related; and how these relationships trans- late to our daily work. We need to understand the parts that make up a safe circuit--how switches, overcurrent protection, and grounding help keep a system safe. We'll discuss single-phase and three-phase alternating current (AC) power systems, and their associated voltage configura- tions. Woven throughout this conversation are references to the National Electrical Code (NEC) and other rules and guidelines. A more complete breakdown of rules of the NEC that are applicable in our work is available on the Set Lighting Technician's Handbook Web site. The next few chapters focus on the equipment and techniques that we use for electrical distribution and rigging,