Assemble, install, test, and maintain electrical or electronic wiring, equipment, appliances, apparatus, and fixtures. Diagnose malfunctioning systems, apparatus, and components to locate the cause of a breakdown and correct the problem. Connect wires to circuit breakers, transformers, or other components. Inspect and upgrade electrical systems, equipment, and components to identify hazards, defects, and the need for adjustment or repair, and to ensure compliance with codes. Test electrical systems and continuity of circuits in electrical wiring, equipment, and fixtures, using testing devices such as ohmmeters, voltmeters.