30-second summary
Medium Voltage – MV
In the United States, the American National Standards Institute (ANSI), specifically ANSI C84.1-2020 defines medium voltage as 2.4 to 69kV.
Medium voltage installations involve equipment that falls into one of five major categories. These are:
- generators,
- switchgear,
- conductors or cables,
- transformers,
- and utilization equipment.
Classification of Voltage Levels- ANSI
In the United States, the American National Standards Institute (ANSI) establishes nominal voltage ratings for 60 Hz electric power systems over 100 V. Specifically, ANSI C84.1-2020 defines:
- low voltage as 240 to 600 V
- medium voltage as 2.4 to 69kV
- 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.
Classification of Voltage Levels – BS 7671
British Standard BS 7671:2008 defines high voltage as any voltage difference between conductors that is higher than 1000 VAC or 1500 V ripple-free DC, or any voltage difference between a conductor and Earth that is higher than 600 VAC or 900 V ripple-free DC.
Classification of Voltage Levels- IEC
In the context of building wiring and the general use of an electrical apparatus, the International Electrotechnical Commission defines:
- high voltage as more than 1,000 volts (V) of alternating current (AC) and above 1,500 V of direct current (DC).
- low voltage as voltage between 50 – 1,000 volts of alternating current and between 120 – 1,500 V of direct current.
- extra-low voltage as lower than 50 V of alternating current and 120 V of direct current
