Overvoltage Categories I-V

(in accordance with EN 60664-1:2007 / VDE 0110-1)

The concept of overvoltage categories is used for equipment energized directly from the low-voltage mains. A similar concept can also be used for equipment connected to other systems, for example telecommunication and data systems.

Equipment of Overvoltage Category I is equipment for connection to circuits in which measures are taken to limit transient overvoltages* to an appropriately low level. These measures shall ensure that the temporary overvoltages that could occur are sufficiently limited so that their peak value does not exceed the relevant rated impulse voltage of the following table" Rated impulse voltage for equipment..."

(*short duration overvoltage of a few milliseconds or less usually highly damped)

Application: Equipment containing electronic circuits protected to this level. Unless the circuits are designed to take the temporary overvoltages into account, equipment of overvoltage category I cannot be directly connected to the supply mains.

Equipment of Overvoltage Category II is energy-consuming equipment to be supplied from the fixed installation.

Application: Appliances, portable tools and other household and similar loads. If such equipment is subjected to special tequirements with regard to reliability and availability, overvoltage category III applies.

Equipment of Overvoltage Category III is equipment in fixed installations and for cases where the reliability and the availability of the equipment is subject to special requirements.

Application: Switches in the fixed installation and equipment for industrial use with permanent connection to the fixed installation.

Equipment of Overvoltage Category IV is for use at the origin of the installation.

Application: Electricity meters and primary overcurrent protection equipment.

All PTR approval data are based on overvoltage category III.