The protection against electric shock of class I appliances not only relies on basic insulation, but also has an additional precaution by connecting accessible conductive parts to the protective earth conductor already installed in the fixed wiring so that the accessible conductive parts are It does not become a live object when the basic insulation is damaged. For example, domestic refrigerators are mostly Class I appliances.
Class II appliances rely not only on basic insulation but also have additional safety precautions for protection against electric shock. The method is to use double insulation or reinforced insulation structure, but there is no protective grounding or measures depending on the installation conditions. For example, most of the electric blankets produced in China are Class II electrical appliances.