OBO lightning and surge protectors are divided into categories 1, 2 and 3 (Class B, Class C and Class D) according to the different requirements of the installation location, protection level and current capacity. This selective lightning and surge protection can ensure a lower level of protection and a higher release capacity.

This division complies with DINEN 61643-11 and other international standards. These standards stipulate the manufacturing criteria, requirements and testing of surge protectors used in AC power lines with rated voltages not exceeding 1000V and rated frequencies between 50 and 60 Hz.