Use power tools safely

Causes of electric shock caused by hand-held power tools
1) Small contact resistance, difficult to get rid of
2) Frequent movement, equipment and power lines are easy to leak
3) Environmental changes and harsh conditions
4) The protection neutral wire is connected incorrectly

The protection categories of electrical equipment are divided according to the protection conditions of electric shock protection by basic insulation protection only - Class 0, Class 0 insulation + internal ground (or zero) - Class Ⅰ double (or strengthened) insulation - Class II protection by safety voltage - Class III

Reasonable selection of hand-held power tools
First, in general places, in order to ensure safety, Class II tools should be selected. If Class I is selected, in addition to correctly grounding or zero connection, protective measures should also be taken:
1) Use insulated appliances (gloves, shoes, MATS, tables)
2) Installed leakage protector 3) safety isolation transformer

Second, in wet places or metal frames, such as good electrical conductivity workplaces, must use class II or Class III tools. If class I is selected, a leakage protector with a leakage action current below 30mA and an action time within 0.1 seconds must be installed

Third, in boilers, metal containers, pipelines and other narrow and well-conductive places, Class III should be used. If class II is selected, a leakage protector with a leakage action current below 15mA and an action time within 0.1 seconds must be installed. And the safety transformer, leakage protector must be placed outside, while someone outside to monitor.

Safety requirements for hand-held power tools
1) The power switch is flexible and firm, and the wiring is not loose
2) The power cord should be rubber sheathed multi-strand copper core flexible wire, and all parts of the cable should be kept intact
3) There shall be no middle joint, which shall not be damaged
4) Class I equipment should have good grounding or zero connection measures
5) Mechanical protection device without damage, deformation, loose
6) Qualified insulation resistance Ⅰ class not less than 2 megohm Ⅱ class not less than 7 megohm Ⅲ class not less than 1 megohm

Precautions for the use of hand-held power tools
1) The name tag should be identified before use, whether it is suitable for the use of the environment
2) Check whether the shell, mechanical protection device, socket, plug and power cord of the tool are damaged
3) Check the voltage and phase number of the power supply
4) For tools not used for a long time, check whether the rotating part is flexible before use, and then test whether the insulation resistance is qualified.
5) When turning on the power supply, check the shell first
6) Should be strictly in accordance with the operating procedures
7) In case of abnormal situation, cut off the power supply immediately

Management of hand-held power tools
1) Tools must be managed by personnel with knowledge of electrical technology and safety
2) Daily inspection must be carried out when the tool is issued and withdrawn, and regular comprehensive inspection and test shall be conducted to develop safe operating procedures
3) Scope and method of use, precautions, inspection items, protective measures, storage and maintenance
4) Establish safety technology management files
5) Instruction manual, certificate of qualification, tool ledger, inspection and maintenance records, use records