What are the special requirements for power tools in classification?

The special requirements of power tools in the classification mainly involve their electrical protection methods, according to the national standard GB3787, power tools are divided into three categories: class I, Class II and class III, each type of tool has its specific requirements and use environment.

Class I tools: These tools rely on basic insulation and ground protection and are suitable for rated voltages exceeding 50 volts. Class I tools feature an accessible conductive portion connected to a protective (ground) wire in a fixed line to prevent electric shock if the basic insulation is damaged. Class I tools have three-pin plugs that need to be grounded.

Class II tools: Class II tools provide double insulation or reinforced insulation, are suitable for rated voltages exceeding 50V, and do not allow grounding devices. Designers of such tools place the operator's personal protective equipment on the tool in a reliable way, so that the tool has a double protective current. Class II tools must use a reinforced insulated power plug that is molded into a flexible cable or cable and cannot be reconnected. Class II tools are marked "back".

Class III tools: Class III tools are safe voltage tools, whose rated voltage does not exceed 50V, and whose protection against electric shock depends on being powered by a safe voltage and not generating a voltage higher than the safe voltage inside the tool. Class III tools are suitable for working in wet or confined places, and Class II or III tools should be selected.

When using power tools, you also need to pay attention to the following special requirements:
Environmental adaptability: Class II tools should be used in general processing sites. Class II or III tools should be used when working in wet areas or on metal frames. Class III tools should be used in confined areas (e.g. boilers, metal containers).
Insulation resistance: For long-term shelved or damp tools, the insulation resistance value should be measured by an electrician before use to see if it meets the requirements. The requirements for insulation resistance are: Class I is not less than 2 megohm, Class II is not less than 7 megohm; Class III not less than 10 megohm.
Appearance and electrical inspection: The appearance and electrical inspection should be carried out before each use to ensure that the tool is in good condition before use.
Power cord and plug: The plug on the tool power cord must not be arbitrarily removed or replaced. The grounding electrode in the plug and socket can only be separately connected to the protective grounding in any case. It is strictly forbidden to connect the ground pole with the neutral line in the plug and socket with a wire.
To sum up, the classification and special requirements of power tools are to ensure the use of safety and extend the service life of the tool, the user needs to choose the right power tools according to the category of tools and the use of the environment, and strictly abide by the relevant safety operating procedures.