Electric welding accident:
After the accident:
Welders in a factory went outdoors for temporary construction of electric welding. Because there is no power socket when the welding machine is connected, he scraped off the paint on each wire head of the cable and bent it into a small hook to hang on the open-air power grid line. Because the zero line was mistakenly connected to the fire line, he touched the shell with his hand while adjusting the welding current and was electrocuted.
Cause analysis:
The machine shell was originally connected to the zero line of the power supply. 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.
After the accident:
There is a young female welder in a shipyard who is burning electric welding in the cabin. Due to the high temperature and poor ventilation in the cabin, she sweated a lot and her canvas overalls and leather gloves were soaked. When replacing the covered electrode, he touched the mouth of the electrode holder, fell backwards due to spasm, and the electrode holder fell on his neck and failed to get rid of it, resulting in electric shock. After the accident, he died after being rescued.
Cause analysis:
1, no-load voltage of welding machine is higher than that of safe voltage.
2. The temperature in the cabin is high, and the welder sweats a lot. The human body's resistance decreases and the risk of electric shock increases.
3. After the electric shock, it was not found in time that the current passed through the human body for a long time, which seriously damaged important organs such as the heart and lungs. So the rescue is invalid.
After the accident:
A welder in a factory was working in a carpenter's room, and the wet sack on the window of the workshop fell on the welder's cable connector. After the welder worked for more than 2 hours, the welder pulled down the switch and got off work. As a result, the sack caught fire at night, which caused a fire.
After the accident, a simulation experiment was specially done to analyze the reasons. The cable joint was covered with five layers of dry sacks, and the welder worked for half an hour, and the sacks caught fire! Experiment with wet sacks, steam after 1 hour, smoke slightly for 2 hours, and catch fire for 5 hours!
Cause analysis:
Due to the weak connection of welded cable joints, poor contact and high contact resistance. When hundreds of amperes of welding current pass through the joint, the resistance heat causes the sack to catch fire, which leads to a fire.