Temporary power use safety management

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This post was last edited by yinkuilin6868 on 2015-12-15 at 15:23. Hazards of electric shock accidents: 1. It is generally believed that electricity poses a greater risk when it passes through the human heart, lungs, and central nervous system; the risk is highest when electricity passes through the heart. Therefore, the current path from hand to foot is the most dangerous. 2. Electric shock can also cause severe spasms that lead to falls, allowing electricity to flow through the entire body and resulting in secondary accidents such as injuries from falling. 3. There are three types of harm that current can cause to the human body: electric shock, electrical burns, and electromagnetic field damage. 4. An electric shock occurs when electricity passes through the human body, disrupting the normal function of the heart, lungs, and nervous system. 5. Electric injury refers to the damage to the human body caused by the thermal effects, chemical effects, and mechanical effects of electric current ； It mainly refers to arc burns, burns caused by splashing molten metal, etc. 6. Physiological damage caused by electromagnetic fields refers to neurological symptoms such as dizziness, fatigue, memory loss, insomnia, and frequent dreams that occur under the influence of high-frequency magnetic fields. How to prevent electric shock accidents: 1. Insulation prevents the human body from coming into contact with live parts by encasing them. Ceramic, glass, mica, rubber, wood, bakelite, plastic, cloth, paper, and mineral oil are all common insulating materials. It should be noted that many insulating materials lose their insulating properties when exposed to moisture, or they can be damaged under the influence of strong electric fields, thereby losing their insulating properties. 2. Protection involves using barriers, guards, cover boxes, and gates to isolate live parts from the outside world. The moving parts of electrical switches generally cannot use insulation and require protection. High-voltage equipment, whether insulated or not, shall be provided with shielding. 3. The spacing is to ensure the necessary safety distance. The spacing serves not only to prevent contact or excessive proximity to live parts, but also to prevent fires, avoid wire confusion, and facilitate operation. During low-voltage operation, the minimum maintenance distance should not be less than 0.1 meters. 4. Grounding refers to the direct connection to the earth; it includes the connection of a certain point on the live parts of an electrical device or circuit to the earth, as well as the artificial connection of a certain point on the non-live parts of an electrical device or other apparatus to the earth when such devices are not in use. 5. Protective grounding: To prevent danger caused by accidental electrification of the exposed, uncharged conductors of electrical equipment, the practice of connecting such equipment to a grounding electrode buried deep in the ground through a protective grounding wire is known as protective grounding. Metal parts that may develop dangerous voltages due to insulation failure or other reasons should all be provided with protective grounding. The metal enclosures of electrical equipment such as motors, transformers, switching devices, lighting fixtures, and other electrical apparatus should all be grounded. In general low-voltage systems, the resistance value of the protective grounding should be less than 4 ohms. 6. Protective zero connection involves closely connecting the metal parts of electrical equipment that are not energized under normal conditions to the neutral wire of the power grid. It should be noted that in a three-phase four-wire power system, the metal enclosures of electrical equipment are usually grounded as well as connected to the neutral wire; this is what is known as repeated grounding protection. It should also be kept in mind that fuses and switches are not allowed to be installed in the neutral wire circuit. Leakage protection devices must be installed on electrical equipment at the workplace. To ensure the safety of people and equipment in the event of a fault, leakage current protective devices should be installed wherever possible. It can detect abnormal signals through the detection mechanism of the protection device when there is a leakage in the equipment or circuits; these signals are then transformed and transmitted by an intermediate mechanism, which in turn triggers the actuator to shut off the power supply automatically, thereby providing protection. The safe voltage used at the work site: 1. According to Ohm’s law, the higher the voltage, the greater the current. Therefore, the voltage that can be applied to a person can be limited to a certain range, such that the current flowing through the body at that voltage does not exceed the allowable level; this voltage is known as a safe voltage. The effective value of the safe voltage at power frequency shall not exceed 50 volts, and for direct current it shall not exceed 120 volts. In our country, the rated values for the effective value of the power frequency are 42 volts, 36 volts, 24 volts, 12 volts, and 6 volts. 2. For hand-held lighting fixtures and ordinary lighting fixtures with a height of less than 2.5 meters, if they do not have special safety structures or measures, a safe voltage of 42 volts or 36 volts should be used. 3. In environments such as metal containers, tunnels, mines, and other locations where the space is limited and movement is difficult, as well as in areas with large-area grounding conductors nearby, a safe voltage of 12 volts should be used when employing handheld lighting devices. Precautions for temporary electricity use at the work site: 1. Do not touch or repair the electrical equipment at the site casually or without permission. 2. Distribution boxes, panels, circuit breakers, push-button starters, sockets, plugs, and wires that are frequently used and come into contact with electricity must remain in good condition; they must not be damaged or have any live parts exposed. 3. Do not use copper wires or similar items in place of fuses, and ensure that the covers of circuit breakers, magnetic switches, etc., remain intact to prevent arcs from occurring during short circuits or fuses from melting and causing injury. 4. Regularly check the protective grounding and neutral connection devices of electrical equipment to ensure they are firmly connected. 5. When moving electrical equipment such as portable fans, lighting fixtures, and welding machines, it is necessary to first cut off the power supply and protect the wires to prevent wear or breakage. 6. When using hand-held power tools such as drill machines and electric grinding wheels, a leakage protector must be installed. The tool’s casing should be properly grounded or connected to the neutral wire, and it is necessary to prevent the wires from being pulled apart when the tool is moved. Insulating gloves should be worn and one should stand on an insulating mat while operating the tool. 7. On stormy days, do not approach within 20 meters of high-voltage poles, iron towers, or the grounding wires of lightning rods. When a high-voltage wire breaks and falls, no one is allowed to enter within 10 meters of the area ； If already within 10 meters, one should jump out of the danger zone on one foot or with both feet. 8. When repairing the equipment, be sure to cut off the power supply and place a warning sign that reads “Do not close the switch – work in progress” in a visible location. Management measures for electrical work at the workplace: Personnel engaged in electrical work are considered to be working in special types of jobs; they must receive specialized safety and technical training as well as pass relevant assessments. Only after passing these tests and obtaining the \"Special Operations Permit\" issued by the comprehensive safety management department can they carry out work independently. Electricians must comply with the safety procedures for electrical work and adhere to maintenance and inspection protocols. In particular, when carrying out high-voltage maintenance tasks, it is essential to follow procedures such as the use of work orders and the assignment of supervisors