International Standard IEC 60038:1983 defines a set of standard voltages for use in low voltage and high voltage AC electricity supply systems.
Contents
Low voltage
Where two voltages are given below separated by "/", the first is the root-mean-square voltage between a phase and the neutral connector, whereas the second is the corresponding root-mean-square voltage between two phases (exception: the category shown below called "One Phase", where 240 V is the root-mean-square voltage between the two legs of a split phase). The three-phase voltages are for use in either four-wire (with neutral) or three-wire (without neutral) systems.
Three-phase 50 Hz
Suppliers using 220 V / 380 V or 240 V / 415 V systems were expected by the standard to migrate to the recommended value of 230 V / 400 V by the year 2003. This migration has already been largely completed, at least within the European Union.
Three-phase 60 Hz
One-phase, three-wire 60 Hz ( American Split-Phase )
Medium voltage
Table 3 of IEC 60038 lists nominal voltages above 1 kV and not exceeding 33 kV. There are two series, one from 3 kV up to 35 kV and another one from 4,16 kV up to 34,5 kV.
High voltage
Table 4 shows nominal voltages above 33 kV and not exceeding 230 kV.
Extra-high voltage
Table 5 is systematically different, as the highest voltage for equipment is the characteristic value exceeding 245 kV. The enumeration begins at 300 kV and ends with 1200 kV.