What is Class 2 and ClassⅡ? What is the difference between ClassⅠand ClassⅡ?

Class 2: When an electronic circuit is powered by Class 2 Power Supply, its output current and power are under the limitation shown in UL1310 Table 30.1, and the risk of fire can be reduced significantly. So, the safety distances and flammability rating of components can be much lower. Therefore, the plastic enclosure of these Power Supplies could use HB flammability rating to reduce cost. This definition comes from UL class 2 power unit (UL1310).

ClassⅠ: Equipment where protection against electric shock is achieved by using basic insulation and also providing a means of connecting to the protective earth conductor in the building where by routing those conductive parts that are otherwise capable of assuming hazardous voltages to earth ground if the basic insulation fails. This means a ClassⅠSPS power Transformer will provide a terminal/pin for earth ground connection.

ClassⅡ: Equipment in which protection against electric shock does not rely on basic insulation only, but in which additional safety precautions, such as double insulation or reinforced insulation are provided, there being no reliance on either protective earth or installation conditions. This means a classⅡSPS does NOT have a terminal/pin for earth ground connection.