Before using handheld electric tools, the casing, handle, power cord, plug, and switch must be inspected to ensure they are intact and undamaged. A no-load test must be performed, and the tool must be approved by the equipment and safety management departments; use is permitted only after compliance is confirmed and an operation permit or formal acceptance record is issued. A "Qualified" tag must be affixed to the equipment.
When using Class I handheld electric tools, operators must wear insulating gear or stand on an insulating mat as required. Reliable neutral-grounding or protective grounding measures must be ensured; the protective neutral wire must be separate from the working neutral wire, and the protective neutral wire must consist of stranded soft copper wire with a cross-section of at least 1.5 mm². A residual current device (RCD) must be installed with a rated residual operating current of no more than 15 mA and an operating time of no more than 0.1 s.
In general locations, Class II tools should be used to ensure safety, equipped with an RCD having a rated residual operating current of no more than 15 mA and an operating time of no more than 0.1 s. The insulation resistance of Class II tools must not be less than 7 MΩ.
For work performed outdoors, in damp locations, or on metal structures, Class II or Class III tools must be used, equipped with splash-proof RCDs. The use of Class I handheld electric tools is strictly prohibited.
In confined spaces (such as boilers, metal containers, trenches, or pipelines), Class III handheld electric tools powered by an isolation transformer are preferred. The isolation transformer and RCD must be installed outside the confined space, and a monitor must be present during operation.
The power cord for handheld electric tools must be a weather-resistant, rubber-sheathed, flexible copper-core cable, and it must not have any splices or joints.
During use, the plug of an electric tool must not be arbitrarily changed; under no circumstances should the plug be bypassed by inserting bare wires directly into the socket. The plug must be promptly disconnected when the tool is not in use or when the working attachment needs to be changed. When inserting the plug, the switch must be in the "off" position to prevent accidental startup.
Frequent inspections must be conducted during use. If faults such as damaged insulation, cracked power cords or cable sheaths, detached grounding wires, cracked plugs or sockets, poor contact, or intermittent operation are detected, the tool must be stopped immediately for repair. When moving portable power tools, always hold them by the handle; do not move them by dragging the rubber power cord. Take care to prevent the cord from being abraded, cut, or punctured to avoid accidents involving personal injury.
For power tools that have been idle for an extended period, the insulation resistance between the windings and the casing must be measured using a 500V megohmmeter before use; the resistance must be no less than 7 MΩ; otherwise, the tool requires a drying process.
Power tools are not suitable for use in special environments containing flammable, explosive, or corrosive gases, or in damp conditions; they should be stored in a dry, clean environment free from corrosive gases. For motors and electrical components with non-metallic casings, avoid contact with solvents such as gasoline during storage and use.
