The single-phase power supply cable for portable electric machinery and hand-held electric tools must use three-core flexible rubber cables, and the three-phase power supply cable must use four-core rubber cables; when wiring, the cable sheath should be inserted into the equipment's junction box and secured.
Before using electric tools, the following should be checked:
(1) The casing and handle should be free of cracks and damage;
(2) The protective grounding or neutral connection should be correct and secure;
(3) The cable or flexible cord should be intact;
(4) The plug should be in good condition;
(5) The switch should operate normally, flexibly, and be free of defects;
(6) The electrical protective device should be intact;
(7) The mechanical protective device should be intact;
(8) The rotating parts should be flexible.
The insulation resistance of electric tools should be regularly measured with a megohmmeter at 500V. If the insulation resistance value between the live parts and the casing is less than 2MΩ, maintenance must be carried out.
After the electrical part of the electric tool has been repaired, it is necessary to measure the insulation resistance and perform an insulation withstand voltage test. The test voltage should be 380V, and the test duration should be 1 minute.
The electrical circuit connecting electric machinery and tools should have a separate switch or socket, and a leakage current-operated protector should be installed. The metal casing should be grounded; it is strictly forbidden to connect multiple devices with one switch.
The rated leakage action current of a current-type leakage protector should not exceed 30mA, and the action time should not exceed 0.1 seconds; the rated leakage action voltage of a voltage-type leakage protector should not exceed 36V.
The operating switch of the electric tool should be placed within easy reach of the operator. When taking a rest, finishing work, or in the event of a sudden power outage during work, the power side switch should be turned off.
When using portable or mobile electric tools, insulated gloves must be worn or an insulated mat must be stood upon; when moving tools, do not carry them by the power cord or the rotating parts of the tool.
When using Class III insulated electric tools in damp or acidic environments, or inside metal containers, reliable insulation measures must be taken and a dedicated supervisor should be appointed. The switch of the electric tool should be within easy reach of the supervisor.
The magnetic chuck drill's chuck surface should be flat, clean, and rust-free. When drilling sideways or upwards, measures should be taken to prevent the drill body from falling after power loss.
When using an electric wrench, the reaction torque support point should be firmly in place and the nut should be securely fastened before starting the operation.
