With the publication of the 1983 edition of this standard, voltage ratings in the field of low voltage products were redefined. The a.c. power supply mains ratings 220 V/380 V and 240 V/415 V have been replaced by a single rating of 230 V/400 V.

For a 20 year transitional period until the year 2003, a + 6%/-10 tolerance corresponding to 244 V and 207 V has been established for countries that used the voltage rating 220 V/380 V. for countries that used the voltage rating 240 V415 V, a + 10/-6% tolerance corresponding to 253 V and 216 V is applicable. Establishing mains tolerances until the year 2003 ensures that electronic equipment designed for the old voltages will function safety until the end of their service life. Starting in 2003, voltage ratings will be expanded to +10%/-10 in all countries.