In North America and in the Philippines, the standard system voltages are specified in ANSI C84.1. For Europe and the rest of the world, the standard system voltages are specified in IEC 60038.
IEC 60038 specifies the standard voltages which applies to
- a.c. transmission, distribution and utilization systems and equipment for use in 50 Hz and 60 Hz having a nominal voltage above 100 V;
- a.c. and d.c. traction systems;
- a.c. and d.c. equipment having nominal voltages below 120 V a.c. (50 Hz and 60 Hz) or below 750 V d.c.
Please note that IEC 60038 does not apply to standard voltages of components and parts used within electrical devices or items of equipment.
IEC 60038 specifies standard voltage values which are intended to serve:
- as preferential values for the nominal voltage of electrical supply systems, and
- as reference values for equipment and system design.
The nominal voltage or highest voltage for equipment specified in IEC 60038 are mainly based on the historical development of electrical supply systems throughout the world, since these values turned out to be the most common ones and have achieved worldwide recognition. The voltage ranges mentioned in this standard have been recognized to be the most appropriate ones as a basis for design and testing of electrical equipment and systems. It is nevertheless the task of system and product standards to define appropriate testing values, testing conditions and acceptance criteria.