IEC 60038


, IEC standard voltages, defines a set of standard voltages for use in low voltage and high voltage a.c. and d.c. 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. The three-phase voltages are for use in either four-wire or three-wire 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.

Voltage conversion schedule

Three-phase 60 Hz

Table 3 of IEC 60038 lists nominal voltages above 1 kV and not exceeding 35 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.

Table 4 35kV - 230kV

Table 4 shows nominal voltages above 35 kV and not exceeding 230 kV.

Table 5 245 - 1,200 kV

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.