21 RELAYS, PHOTO RELAYS, CURRENT SENSORS, [ FLASHERS, AMPLIFIERS, ] ADAPTERS FOR LIGHTING CONTROLS FOR LUMINARIES, CIRCUITRY FOR CONTROLLING CAPACITATORS TO CORRECT THE POWER FACTOR, EXCLUDING CAPACITORS PER SE, LIGHTNING ARRESTORS, PICK-UP ASSEMBLIES FOR POWER LINES; ELECTRONIC EQUIPMENT FOR ELECTRIC UTILITY SYSTEMS-NAMELY, SENSING EQUIPMENT, CAPACITOR SWITCHING EQUIPMENT, EXCLUDING CAPACITORS PER SE, LOAD SURVEY AND PROTECTIVE RELAYING EQUIPMENT