High voltage refers to electrical potential large enough to cause injury or damage. The definition of high voltage varies depending on the industry and safety regulations. Here are some examples of high voltage classifications:

• The International Electrotechnical Commission (IEC) defines high voltage as any voltage above 1000 volts for alternating current (AC) systems and at least 1500 volts for direct current (DC) systems.
• The American National Standards Institute (ANSI) defines high voltage as 115 kV to 230 kV, extra-high voltage as 345 kV to 765 kV, and ultra-high voltage as 1,100 kV.
• The National Electrical Code (NEC) considers anything over 600 volts to be high voltage.
• High voltage lines are those above 36 kV (i.e. 36,000 volts), according to the International Standard of the International Electrotechnical Commission.

Its important to note that voltages as low as 50 or 600 volts can be considered high voltage depending on the safety regulations.