Per IEC1010 Overvoltage Installation Category
Overvoltage Category I
Equipment of Overvoltage Category I is equipment for connection to circuits in which
measures are taken to limit the transient overvoltages to an appropriate low level.
Note: Examples include protected electronic circuits.
Overvoltage Category II
Equipment of Overvoltage Category II is energy-consuming equipment to be supplied from the
fixed installation.
Note: Examples include household, office, and laboratory appliances.
Overvoltage Category III
Equipment of Overvoltage Category III is equipment in fixed installations.
Note: Examples include switches in the fixed installation and some equipment for industrial
use with permanent connection to the fixed installation.
Overvoltage Category IV
Equipment of Overvoltage Category IV is for use at the origin of the installation.
Note: Examples include electricity meters and primary overcurrent protection equipment.
14