Test, repair, modify, calculate, operate, maintain, overhaul and calibrate small to large industrial air conditioning units, small to large refrigeration coolers and freezers, chiller systems, small to industrial humification and dehumidification systems, air cleaners, heat pumps, clean room systems, small to industrial ventilation and exhaust systems, pneumatic systems, propane, steam and electrical heating systems, small to 150 horsepower reciprocating and screw compressors, electrical lines, circuits, systems, subsystems, controls, fixtures with their relays, switches, receptacles, and controllers. Maintain and troubleshoot a variety of complex electrical systems and equipment such as series, parallel, and compound circuits for single and multiple phase alternating current of varying voltage, amperage, and frequency; wiring systems in industrial complexes and in buildings; and power or regulating and control circuits and distribution panels to industrial machinery, computers, clean rooms or other electrical equipment.