Hand-held power tools are tools that are often used in labor, and the incidence of electric shock accidents is also very high. To this end, national standards stipulate that handheld power tools are divided into three categories:
Class I handheld power tools are rated at 220 ∨ and above, and have only internal insulation. They must be connected with a zero (ground) protection and leakage protector or safety isolating transformer. These tool housings are generally all-metal cable lines are three plugs.
Class II tools have a rated voltage of 220 ∨ and above, but they have reinforced or double-layer insulation inside, and their safety performance is excellent. Class I tools, but the measures taken by Class I tools should also be used. In order to distinguish between Class I tools, the Class II tool has a "Back" mark on the label. Such tool housings generally have metal boxes, non-metal, but the hand-held parts are non-metallic as shown below:
Class III tools are powered by a safe voltage, rated voltages up to 42 ∨, and safety performance is significantly better than Class I tools and Class II tools. These tool housings are all plastic
Precautions
Since hand-held power tools need to be moved frequently during use, workers often come into contact with them, and they are often used in tight grips, so the danger is relatively large, and special attention should be paid to the following items during use:
1. Class II tools are used in general places. If a Class I tool is used, a leakage protector and a safety isolating transformer must be used. Otherwise the user must wear insulated gloves, wear insulated boots or stand on the insulation table (mat).
2. Class II or Class III tools should be used for work in wet locations or on metal frames. If the I tool is used, a leakage protector with a rated leakage current of not more than 30 mA and an operation time of not more than 0.1 second must be installed.
3. Class III tools should be used in narrow places. If a Class II tool is used, a leakage protector with a rated leakage current of not more than 15 mA and an operating time of not more than 0.1 second must be installed.
4. Before use, check whether the tool casing and handle are broken or damaged, whether the zero (ground) is correct, whether the wire and plug are intact, whether the switch is normal and flexible, whether the electrical protection device and the mechanical protection device are intact, and whether the tool rotation part is correct. flexible.