IEC 60038
International Standard IEC 60038:1983 defines a set of standard voltages for use in low voltage and high voltage AC electricity supply systems.
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
230 V / 400 V
400 V / 690 V
1000 V
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.
Voltage conversion schedule
Three-phase 60 Hz
120 V / 208 V
240 V
277 V / 480 V
