In the National Electrical Code, Article 100 and the review of the Code's implementation treat any nominal voltage over 1000 volts as the administrative threshold where “over 1000 volts” articles apply; those provisions address equipment and installations for voltages. In the National Electrical Code, Article 100 and the review of the Code's implementation treat any nominal voltage over 1000 volts as the administrative threshold where “over 1000 volts” articles apply; those provisions address equipment and installations for voltages. Modern electrical substation showing low, medium, and high voltage equipment with VIOX switchgear and distribution systems. Voltage classifications are not universally standardized—they vary by region and governing body. The two primary standards organizations are: The IEC standards, particularly. These guidelines for the safe management of high voltage electrical installations are issued under Section 33AA of the Electricity Act 1945 (WA) by the Director of Energy Safety and are endorsed by WorkSafe. This includes electrical equipment. While the industry frequently uses the terms “low,” “medium,” and “high” voltage, the National Electrical Code (NEC) does include a formal threshold used throughout the Code: Article 100 defines high voltage as a potential difference of more than 1000 volts, nominal. However, the term "HV" can also refer to voltages as low as 50 volts in some safety. High-voltage distribution boxes are super important in today's electrical setups. Think of them as the main hubs that make sure electricity gets to where it's needed, efficiently. Inside these boxes, you've got some key parts like circuit breakers, transformers, and protective relays.