Causes of the hottest low voltage electric shock a

Causes of low-voltage electric shock and safe operation technology

there are two types of industrial accidents that are prone to occur when electricians repair low-voltage electrical devices, namely, electric shock accidents and high-altitude fall accidents. Among them, high-altitude fall accidents are often caused by electric shock, which can cause serious injury or death

under normal circumstances, electricians cut off power for maintenance operations, and live operation is not allowed. However, due to various reasons, there are often sudden calls at the maintenance point. For example, the main switch of the disconnected power supply was inadvertently closed by someone, and the circuit breaker without obvious disconnection point (such as automatic switch and contactor) was strongly vibrated, resulting in a bouncing inadvertent closing in the research and development process of bu6800 injection molding machine. If there is accidental electrification at the maintenance point, electricians are likely to have electric shock accidents. Therefore, electricians must strictly implement the safety work procedures for power outage maintenance during daily inspection and maintenance to prevent electric shock accidents

1 possible electric shock circuit

there are usually three kinds of electric shock circuits that may be caused by electricians during maintenance:

(1) electric shock circuit between two wires: when two different parts of the overhaul body touch the exposed parts of two wires at the same time, or two wiring terminals, the human body connects the circuit between the two wires to form an electric shock circuit. If it touches two phase wires of a low-voltage line, Then the human body bears 380V line voltage; If the human body touches a phase line and a neutral line, the human body bears a phase voltage of 220V

(2) electric shock circuit between line and ground: when the human body of the repairer touches a live phase line and conductive ground, wall column, water pipe, etc. at the same time, the current will flow through the human body, buildings and the ground to form a circuit. The human body may also bear 220V voltage, and the current flowing through the human body is also a serious threat to life

(3) electric shock circuit of human intervention circuit: when electricians are repairing single line control switches (such as ordinary wire switches), fuses or wire connection points, if the human body touches two terminal blocks or disconnected two wire ends at the same time, once the circuit is powered on, the human body will be connected into the circuit. At this time, the current passing through the human body is related to the power of electrical appliances, which often exceeds the level that the human body can bear in these 10 fields

2 safe operation technology to avoid the formation of electric shock circuits

in order to prevent the formation of the above three kinds of electric shock circuits, electricians must strictly implement the following three safe operation principles when carrying out low-voltage live maintenance work:

(1) single line operation: during maintenance work, the human body must not touch two wire ends, or two wiring terminals, or two contacts at any time, and must process one wire end and one wire end. All adjacent live bare conductors that may be touched by carelessness must be covered in advance at the end of June

(2) isolation from the earth: during maintenance, all parts of the human body must be reliably insulated from the earth (including conductive buildings and pipelines connected with the earth). Therefore, electricians must wear electrician insulated shoes, protective work clothes, tools with insulated handles, and dry ladders of bamboo or wood structure to climb in strict accordance with safety work regulations. If the height is not equal, dry wood and other insulating materials can be used to pad under it. At the same time, the human body cannot touch the building during operation. In addition, when accepting the delivery of tools or parts by humanists who are not isolated from the earth, the maintainer must stop the operation and keep his hands away from the maintenance point. In this way, the formation of electric shock circuit between line and ground can be avoided

(3) breaking current circuit: electricians should first eliminate the possible closed circuit formed by the circuit when repairing individual circuits of electrical appliances. For example, when repairing the electric light switch, the bulb must be removed first, so that even if the human body touches the two terminals of the switch at the same time, the closed circuit will not be formed due to the intervention of the human body. For another example, when replacing the whole fuse on the distribution board, the power plug of the mobile electric appliance must be unplugged first, so that even if both hands touch the upper and lower connecting wire ends at the same time, a closed circuit will not be formed due to human intervention. In addition, when overhauling the lamp holder or wire hanging box, the electric lamp switch must be disconnected, so as to avoid the electric shock circuit formed when touching two connecting terminals at the same time (also belongs to interventional electric shock, when the human body replaces the electrical appliance, and the human body becomes a load in the circuit)

it must be emphasized that: cut off power as much as possible, check electricity before work, and prevent sudden calls. If you have to work with electricity as a last resort, the above three safety measures to avoid all kinds of electric shock must be adopted at the same time. If only one or two of them are used, electric shock accidents will still occur. For example, if the safety measure of isolation from the earth is not taken, even if the two measures of single line operation and breaking the circuit circuit are strictly taken, the electric shock circuit between the line and the ground will still be formed; If only the measures of isolation from the earth are taken, the other two kinds of electric shock circuits cannot be avoided. Therefore, the above three measures must be taken at the same time to ensure the safe operation of electricians