1. Electric shock between the two wires. When different parts of the human body touch the exposed part of the two wires or the ends of the two wires at the same time, the human body turns on the circuit between the two wires to form an electric shock circuit.
2. The electric shock between the phase line and the ground. When the human body touches a charged phase line, a metal casing with electrical insulation damage and electrical ground, and conductive ground, wall column, various pipelines, machinery and equipment, etc., the current will form a current loop through the human body and the earth. .
3. The human body is electrically connected to the circuit. When the unipolar control switch, fuse or wire connection point is repaired, if the human body touches two terminals or two wire ends at the same time, once the line is charged, the human body will be connected to the load current loop.
Safe operation techniques to avoid the formation of electric shock circuits
1, single line operation. At the time of inspection or overhaul, the human body must not touch two wires, terminals or contacts at the same time. When operating, it must be wrapped one line at a time. Adjacent live bare conductors that may be touched must be pre-shielded.
2. Insulated from the earth. All parts of the human body must be reliably insulated from the earth (including conductive buildings and pipes that are connected to the earth). Therefore, the maintenance personnel must wear insulated shoes, protective clothing and tools with insulated handles, as well as dry ladders with bamboo and wood structures (or with dry wooden benches) in strict accordance with the regulations. Even if it is not ascended, an insulating board such as a dry wood board or a rubber sheet is applied under the foot, and the human body cannot touch the equipment or the building during operation. In addition, when picking up parts that are not insulated from the ground, the inspector must stop the operation and the hands must be removed from the inspection point to avoid electric shock between the phases.
3. Disconnect the load current loop. Overhaul electrical equipment should first eliminate the closed loop that current may form. If the entire fuse is replaced on the power distribution board, the load must be disconnected first, so that the electric shock circuit will not be formed even if both hands touch the upper and lower connection ends at the same time. In addition, when the lamp or junction box is inspected, the light switch must be disconnected, so as to avoid touching the two terminals at the same time to form an electric shock circuit.
It must be emphasized here that the maintenance work must be taken care of and the power must be cut off. Prior to overhaul, any electrical equipment should be considered to be live, so safety measures such as power outages, power inspections, and grounding lines must be implemented to prevent sudden calls and accidents.