What is a High Voltage and Low Voltage Complete Set? A high voltage and low voltage complete set refers to protective, switching, and control devices as an integrated system within one enclosure (safe). In most designs, these sets take care of more than 1 kV-high-voltage-and less than 1 kV. The key is high voltage equipment, a vital element of today's power systems that processes and regulates high-voltage electricity, usually over 1,000 volts AC or 1,500 volts DC. These include transformers, circuit breakers, insulators, switches, and other components used in power transmission and distribution. 5 kV DC) to transmit large power across long distances—vital for utilities, industrial and grid systems.