Typical ANSI/NEMA (American National Standards Institute, National Electrical Manufacturers Association) switchgear is rated for up to 635 volts with a continuous current main bus rating of up to 10,000 amps (for supplying power from parallel sources). Rated voltage does not exceed 1 000 V AC or 1500 V DC. Generation, transmission, distribution and control of electric energy. Electrical equipment of. IEC 60439, the standard for low-voltage switchgear and controlgear assemblies, was under restructuring from the last decade. This standard has brought considerable clarity in technical interpretation.