Electricity safety knowledge summary

First, voltage and safety voltage

The potential difference between any two points in a circuit is called the voltage between two points. It is the basic physical quantity in electricity and the unit is V (Volt). With the voltage, the current flows from the high potential place to the low potential through the electric equipment, and the electric appliance operates accordingly. The higher the voltage, the greater the energy and the greater the danger of an electric shock.

The voltage is divided into two categories of DC voltage and AC voltage. DC voltage means that the magnitude and direction of the voltage do not change with time, and the magnitude and direction of the AC voltage change periodically with time.

Generally used small electrical appliances, household appliances and lighting and other facilities, the use of rated voltage is generally 220V , common power equipment such as three-phase asynchronous motor rated voltage of 380V , large-scale power facilities rated voltage is higher. In long-distance transmission lines, high-voltage power transmission is used. Generally, the transmission voltage between urban and rural areas is 10KV or 35KV , while in long-distance field high-voltage transmission lines, the voltage is 220KV or 500KV ( High-voltage lines in our company's Taihe Paper Factory The voltage is 220KV ). The higher the voltage, the greater the energy and the greater the risk of electric shock.

From the standpoint of protecting personal safety, it is safe voltage to say that the human body can automatically get rid of the voltage of the electric shock current. According to GB3805 - 83 a predetermined "safe voltage", the voltage refers to the voltage rating of the security level of 42, 36, low-voltage 24, 12, 6V's.

The safety voltage that people touch under normal circumstances is 36V. Due to the effect of human body resistance, the current flowing through the human body is very small and there is no danger, but the human body resistance will change with different conditions. When the human health status or mental state is poor, or when the body surface and clothes are soaked, the human body resistance will drop to a low value. At this time, when working at height, it may fall due to electrical shock and body imbalance. Therefore, the safe voltage cannot be understood as an absolutely no dangerous voltage.

In order to prevent electric shock accidents, in the industrial and mining enterprises, the portable lighting fixtures often used, and the lighting devices attached to various types of machine tools, the voltage used is generally safe voltage. Safe voltage is also used in some amusement facilities. The use of safety must comply with the relevant provisions to ensure the safe use of electricity.

Second, electrical insulation

"Upstairs, downstairs and downstairs, electric light phones" have made us yearn for a better life. Now that we have entered the era of electrical appliances, electricity has brought us endless convenience. However, electricity is energy, and it cannot be seen and touched. Therefore, if it is used improperly, electric shocks will occur.

Good insulation is a necessary condition for ensuring the normal operation of electrical equipment and electrical lines, and it is also one of the most basic safety measures for preventing electric shock. The insulator can be used to isolate or enclose the charged body and prevent electric shock or leakage.

Insulation usually has gas, liquid and solid insulation. The most widely contacted are solid insulating materials such as ceramics, rubber, plastics, and bakelite. However, once the solid insulation is destroyed by a strong current or burned by overheating, its insulation performance will be lost. Therefore, the insulation material of electrical wiring and equipment must be compatible with the voltage level, operating environment, and operating conditions used.

It should be noted that corrosive gases, vapors, moisture, conductive dust, and mechanical damage can degrade or even destroy the insulating properties of the insulating material. The long-term effects of sunlight, storms, and other factors can also cause aging of insulation materials and gradual loss of insulation. Therefore, always check the insulation status of equipment and lines, and replace insulation materials that have been damaged and aged at any time.

Insulating tools are divided into basic safety equipment and auxiliary safety tools. The basic safety uses insulating rods and insulating clamps that are used by electricians and can withstand the equipment operating voltage for a long time. The auxiliary safety uses insulating shoes, insulating gloves, insulating mats, insulated platforms, etc. , Such items can only play a protective role; As for the daily use of wire cutters, screwdriver plastic sheath and wooden handle, can only provide protection under the voltage of less than 500 volts.

Our commonly used insulating tapes are generally used for low voltage connector joints up to 500 volts. Plastic insulation tape should be used outdoors; rubber insulation tape should be used in wet and submerged environments. In order to prevent insulation and heat from failing, the circuit connector must be spliced ​​and densified to prevent false connection before the insulation tape is wrapped. Absolutely not to use medical tape instead of insulating tape to avoid accidents.

Third, household safety electricity

With the development of science and technology and the improvement of the quality of life of employees, electric appliances such as televisions, refrigerators, rice cookers, hair dryers, electric irons, electric blankets, induction cookers and other electric appliances, and air conditioners, computers, video recorders, and washing machines Domestic appliances such as "machine" are increasingly entering the family. In order to ensure personal safety, special attention should be paid to household electricity safety issues:

1 . Not overloaded with electricity. The total current of all kinds of electrical appliances used cannot exceed the maximum rated current of the power meter and the power cord, so as to avoid overheating and burning, especially for temporary use of electricity such as decoration.

2 . Install the protector. Be sure to install a leakage current and over-voltage dual function protector on the outlet side of the self-appliance household appliance to avoid tripping and cutting off the power automatically when the home appliance is leaking, the person has electric shock, the power supply voltage is too high or too low, and the personal and household appliances are protected. Safety.

3 . The housing of household appliances should be reliably grounded. Must be equipped with three-hole socket, and a good ground wire to prevent the risk of electric shock from the shell charged.

4 . Substitutes are strictly prohibited. Can not use copper wire, aluminum wire, iron wire to replace the fuse; can not use signal transmission line instead of the power cord; can not use medical white tape instead of insulating black tape.

5 . Prevent over-current of electrical components. Electric cookers such as rice cookers, electric kettles, and electric heaters should not be easily connected to low-power lighting sockets to prevent over-current burning. Unplug all plugs when unexpected power failure occurs. Special attention should be paid to all types of heater plugs.

6 . The correct way to repair electrical appliances. Do not touch and operate appliances with wet hands or wet cloths. Do not bundle wire with wire and do not wrap it around nails or other metal objects.

7 . To develop good habits. Make people go out of power, power off the switch, touch the shell with the back of the hand, maintenance checks to power off, when plugging the power plug, the hand should be held in the insulating part, do not touch the metal sheet on the plug, not to mention the fingers Insert into the jack.

8. If abnormality is found, switch off the power immediately. Abnormal voltage rises, unusual noises, odors, temperatures, smoke, and flares are detected. Immediately disconnect the power supply, check, or extinguish the fire. In the event of an electric shock, one should first turn off the power, or use a stick or other insulating object to remove the electric shock from the live body.

Fourth, prevent lightning damage

Lightning is a natural phenomenon of discharge. When the charged cloud of lightning approaches the protrusions on the ground, intense discharge occurs between them. There will be strong flashes of light and explosion roars at lightning storm discharge sites. This is the lightning thunder that people see and hear.

The lightning current generated by lightning is the main destroyer, and its harm is direct lightning strike, induced lightning strike and intrusive lightning guided by overhead lines. For example, overhead lines used in various lighting, telecommunication and other facilities may introduce lightning into the room, so strict precautions should be taken.

(I) Lightning strikes

1 . Lack of high-rise buildings, storage tanks, etc. that are unqualified by lightning protection equipment or lightning protection equipment;

2 . There is no well-grounded metal roof;

3 . Buildings, trees, etc. in wet or empty areas;

4 . Due to the electrical conductivity of the smoke, the chimney is particularly vulnerable to lightning strikes;

5 . There are wireless antennas on the building and there are no arresters and no good grounding.

(B) Prevention of Lightning

1 . Lightning protection devices are installed on the building. That is, using a lightning protection device to introduce lightning current into the earth and disappear.

2 . In thunderstorms, people should not go near high-voltage transformer rooms, high-voltage power lines and isolated high-rises, chimneys, poles, trees, flagpoles, etc., not to stand on empty highlands or to shelter under big trees.

3 . You cannot use an umbrella with metal pillars. Do not use metal tools, such as iron rods, when working in suburban or open air.

4 . Do not wear wet clothes near or stand on the cargo of open metal goods.

5 . Don't open the phone on the top of the mountain during thunderstorms, let alone make phone calls.

6 . Do not touch and approach the grounding conductor of the lightning protection device during thunderstorms.

7 . Thunderstorm days, in the home should leave the lighting line, telephone lines, television lines and other lines, in order to prevent people from being hurt by lightning.

V. Safe use of hand-held power tools

Hand-held power tools are very convenient to use, but due to the fact that they are used by people under tight gripping, once the casing is leaking, current will pass through the human body, causing very serious consequences. Therefore, the use of hand-held power tools should pay more attention to power safety issues.

1 . When using any hand-held power tool, it must be operated in accordance with safety regulations. Operators should wear protective clothing such as insulating shoes and insulating gloves.

2 . The power supply for hand-held power tools must be equipped with a leakage protector. The plug must be used with a matching socket. When using a 220- volt three-pin plug, do not bend the ground pins and use it directly on the two-hole socket to prevent leakage of the housing and cause electric shock. .

3 . Before using for the first time, it should be tested for zero connection and insulation and can be used only after confirmation.

4 . The wires holding power tools must use rubber sheathed wires. Do not use plastic sheathed wires. The ends of the wires must be securely connected and the internal connections must be correct. In particular, the cable sheaths at the ends of the handles should be intact.

5 . Cables should not have joints, the length should not exceed 5 meters in order to avoid mechanical damage. Do not pull the wire during use and avoid pulling the wire. Also do not overturn, to avoid the power connector in the handle wrapped around, pull off, so that the chassis charged or a short circuit.

6 . To prevent the working end of the hand-held power tool from causing mechanical damage to the human body.

7 . Do not use hand-held power tools at flammable and explosive work sites to avoid sparking fire.

8. When moving a portable power tool, it is only possible to hold the handle by hand, and it is not allowed to mention the wire or the chuck. When working at heights, there should be appropriate safety protection measures.

Sixth, how to prevent electric shock

Common technical measures to prevent electric shock should include: insulation, shielding, spacing, grounding, zero, installation of leakage protection devices and the use of safe voltage. On the premise of perfecting technical measures, we must also strictly abide by the safety operation procedures so as to minimize the occurrence of electric shock accidents.

1 . Conscientiously study the knowledge of safe use of electricity and improve your ability to prevent electric shocks. Pay attention to the electrical safety distance and do not enter the place where the identified electrical hazard signs are located. Do not touch or touch the electrical equipment, especially when the human body sweats or the hands and feet are wet, do not operate electrical equipment.

2 . In the event of electrical equipment failure, do not dismantle it by yourself and have it repaired by an electrician who holds an electrical operation permit. When a public utility or a high-voltage line fails, an alarm call is required to be handled by the power department.

3 . According to the design specifications and operating specifications construction, ensure the installation quality. Do not use poor quality, worn-out damaged wires and electrical equipment.

4 . Electrical equipment must have protective zero and protective grounding devices. And often check to ensure that it is safe and reliable.

5 . According to the safety ampacity configuration equipment and wires, the load is not increased arbitrarily to prevent short circuit and leakage due to over-current heating. Do not arbitrarily increase the size when replacing the line fuse, and do not use other metal wires instead.

6 . When repairing electrical equipment and moving electrical equipment, it is necessary to completely turn off the power, and hang a “safety signboard with someone working and no closing” in a prominent position. Unexperienced equipment and lines are considered to have electricity. Devices with capacitors must be discharged first, and removable devices should be prevented from breaking the wires.

7 . The distribution boxes, switchboards, blades, buttons, sockets, and wires that are frequently contacted during use should be intact. Insulation aging and damage should be promptly replaced.

8 . Machine work lights, portable temporary lights, use a safe voltage of no more than 36 volts.

9 . Thunderstorm days should be away from high voltage poles, towers and lightning rods. Lightning rods should be intact and tested regularly.

10 . Every construction should avoid the protection distance of high-voltage lines. April 8, 2004, a company in Jieyang City of Guangdong touched kilovolt high-voltage wire in the air when 20 people lift formwork, resulting in 12 deaths. The lessons of such blood must be kept in mind.

11 . To at least 20 meters away from the grounding point, as already within 20 meters, and to jump off one foot or foot beyond 20 m, the step voltage to prevent high-voltage electric shock when landing.

12 . In the event of an electrical fire, immediately shut off the power supply and extinguish the fire with yellow sand and carbon dioxide extinguisher. Never use water or foam fire extinguisher to extinguish the fire.

The information in this article comes from the Internet and was reorganized and edited by China Rescue Equipment Network.