scope:

This standard establishes nominal voltage ratings and operating tolerances for 60-hertz electric power systems above 100 volts and through 230 kilovolts. It also makes recommendations to other standardizing groups with respect to voltage ratings for equipment used on power systems and for utilization devices connected to such systems.

NOTE-For completeness, information on extra-high voltage systems (345 kilovolts and higher) from American National Standard for Power Systems - Alternating-Current Electrical Systems and Equipment Operating at Voltages above 230 kV Nominal - Preferred Voltage Ratings, ANSI C92.2-1987, is also included as a footnote to table 1.