Example 1: The welder opened the welder without authorization and was electrocuted.
1. Accident process
Welders in a factory go to outdoor temporary work to weld. When welding, because there is no power switch box, the welder removes the rubber from each wire end of the cable and connects it to the open-air power grid line respectively. Because the zero line was connected to the fire line by mistake, he touched the shell with his hand while adjusting the welding current and was electrocuted.
2. Analysis of main reasons
Because the welder is not familiar with the knowledge about electrical safety, the neutral wire and live wire are wrongly connected, which leads to the electrification of the welding machine shell and the accident of electric shock death. 3. Main preventive measures
Wiring of welding equipment must be completed by electricians, and welders are not allowed to operate without authorization.
Example 2: When changing the covered electrode, you touched the mouth of the electrode holder and got an electric shock.
1. Accident process
A young female welder in a shipyard is welding in the cabin. Due to the high temperature and poor ventilation in the cabin, she was sweating and soaked through her work clothes and leather gloves. When replacing the coated electrode, he touched the mouth of the electrode holder, and fell back due to spasm, and the electrode holder failed to get rid of it, resulting in electric shock. After the accident, he died after being rescued.
2. Analysis of main reasons
(1) No-load voltage of welding machine is higher than that of safe voltage.
(2) The temperature in the cabin is high, the welder sweats a lot, the human body resistance decreases, and the risk of electric shock increases.
(3) The electric shock was not found in time, and the current passed through the human body for a long time, seriously damaging important organs such as the heart and lungs, and the rescue was invalid.
3. Main preventive measures
(2) When in cabin activity, a guardian should be set up to keep an eye on the welder's dynamics at any time. When encountering danger signs, you should immediately pull the switch for rescue.
Example 3: The circuit board is burnt out, and the welding machine shell is electrified, resulting in an accident.
1. Accident process
When welder A and welder B spot-welded the iron shell in a factory, they found that one of the welder's lead coils had been broken, and the electrician only found a flexible cord to be replaced by welder B.. When changing wires, Party B found that the bolts of the wiring board of the primary wire were loose, tightened them with a wrench (Party A was not at the scene at this time), and left the scene after several trial welds. After returning, Party A didn't know the situation, so he started spot welding. After welding only one, he fell to the ground with a scream. Worker c immediately pulled the brake, but died because of the delay in rescue.
2. Analysis of main reasons
(1) Because the circuit board was burnt out, the coil collided with the shell of the welder, resulting in short circuit.
(2) The shell of electric welding machine is not grounded.
3. Main preventive measures
(1) Equipment maintenance shall be carried out by electricians.
(2) The welding equipment shall be grounded.
Example 4: The welder did not wear protective equipment as required and was electrocuted.
1. Accident process
In the structural workshop of a machinery factory in Shanghai, several welders are welding the product base. When a welder turned on the switch with his right hand and supported the welder with his left hand, he immediately fell to the ground with a loud cry and was sent to the hospital for rescue and died.
2. Analysis of main reasons
(1) The welding machine shell is charged.
(2) The welder did not wear insulating gloves and shoes.
(3) Grounding fault of electric welding machine.
3. Main preventive measures
(1) Before working, check whether the insulation layer of the equipment is damaged and the grounding is good.
(2) Is there a problem with the welding machine?
(3) When pushing and pulling the power switch, wear insulating gloves, move quickly and stand on the side.