Safe electricity
I. Overview of electric power
Use and maintain electrical equipment after taking necessary safety measures. Electric energy is a convenient energy source, and its wide application has formed the second technological revolution in modern human history. It has effectively promoted the development of human society, created great wealth for mankind and improved human life.
Second, the harm of electricity
If we do not pay attention to the safe use of electricity in production and life, it will also bring disaster.
For example, electric shock may cause personal injury or death, electric sparks caused by equipment leakage may lead to fire and explosion, and high-frequency electrical equipment may produce electromagnetic pollution.
Third, electricity safety.
1. How to use electricity safely
It's unbearable hot in summer, and the air conditioning fans are all on. Fire and electric shock accidents caused by the use of these electrical appliances occur every year. How to make science of electricity safe is an important matter that every family must pay attention to. First of all, the bearing capacity of watt-hour meter and low-voltage line should be considered. The electric power that a watt-hour meter can withstand is similar to the value of voltage multiplied by current. The voltage of domestic electricity is 220 volts. For example, if a 2.5-amp watt-hour meter is installed at home, the power it can withstand is 550 watts, and a 600-watt rice cooker cannot be used. In this way, the electric power that a 5-amp watt-hour meter can bear is 1 100 watt.
Secondly, it should be considered that a socket allows several appliances to be plugged in. If the sum of the maximum power of all electrical appliances does not exceed the power of the socket, there is generally no problem. When using sockets with more than three pairs of jacks and using high-power appliances such as air conditioners, electric cookers, rice cookers and electric water heaters at the same time, the sum of the powers of these appliances should be calculated first. If the limited power of the socket is exceeded, the socket will burn out due to excessive current. At this time, the number of electrical appliances used at the same time should be reduced to keep the total power within the allowable range of the socket.
In addition, the installed circuit breaker must use the corresponding standard fuse. Do not use other metal wires instead, otherwise it will easily cause fire and damage electrical appliances. If the fire is caused by the fire of household appliances, you must cut off the power supply first and then put out the fire to avoid electric shock and personal injury.
2. Safe use of electricity
The popularity of household appliances such as refrigerators, televisions, washing machines and air conditioners has brought a lot of convenience to people's lives. But pay attention to the safe use of power supply to avoid unnecessary harm.
Electrical appliances with metal shell should use three-pin power plug. Some household appliances may leak electricity when they fail or get wet. Once the shell is charged, use a two-pin power socket, which may cause electric shock after human contact. Household appliances that consume a lot of electricity should use a separate power socket. Because both wires and sockets have specified current carrying capacity, if a variety of electrical appliances share a power socket, when the current exceeds its rated flow, the wires will heat up, and the plastic insulating sleeve may melt and cause combustion.
When the voltage fluctuates greatly, use a protector. In daily life, there is often an instantaneous power failure or power supply voltage fluctuation, which is a threat to the refrigerator. If the power supply is restored within a short time (3 ~ 5 minutes) after the power failure, the starting current of the refrigerator compressor is several times larger than the normal starting current, which may burn out the compressor.
Fourth, how to use electricity safely.
1. Why does the lighting switch have to be connected to the live wire?
If the lighting switch is installed on the zero line, although the light is not on when it is turned off, the phase line of the lamp holder is still on, and people will think that the light is not on and will mistakenly think that it is in a power-off state. In fact, the ground voltage of each point on the lamp is still a dangerous voltage of 220 volts. If people touch these actually charged parts when turning off the lights, it will cause an electric shock accident. Therefore, all kinds of lighting switches or switches of single-phase small-capacity electrical equipment can only be connected in series on the live line to ensure safety.
2. How to correctly install the single-phase three hole socket? Why?
Usually, single-phase electrical equipment, especially mobile electrical equipment, should use three-core plug and its supporting three hole socket. There is a special protective zero (grounding) jack in three hole socket. When using zero protection, it is very dangerous for someone to directly connect the wiring pile head of this hole with the zero line that only leads into the socket at the bottom of the socket. Because in case the zero line of the power supply is disconnected, or the fire (phase) line and the zero line of the power supply are connected reversely, its shell and other metal parts will also bring the same voltage as the power supply, resulting in electric shock.
Therefore, when wiring, the special grounding jack should be connected with the special protective grounding wire. When zero protection is adopted, the zero line should be led out from the power supply side, and the zero line introduced into the socket should not be used nearby.
3. Why is it forbidden to bury plastic insulated wires directly in the wall?
(1) Plastic insulated conductor will age and crack after long-term use, and the insulation level will be greatly reduced. When the line is overloaded or short-circuited, it is easier to accelerate the insulation damage.
(2) Once the wall is damp, it will cause a large area of leakage and endanger personal safety.
(3) Plastic insulated wires are directly buried, which is not conducive to line maintenance and repair.
4. Why should I use a leakage protector?
Leakage protector, also known as leakage protection switch, is a new type of electrical safety device. Its main purposes are:
(1) Prevent electric shock accidents caused by leakage of electrical equipment and circuits.
(2) To prevent single-phase electric shock accidents in the process of electricity utilization.
(3) Cut off the single-phase grounding fault in the operation of electrical equipment in time to prevent electrical fire accidents caused by leakage.
(4) With the improvement of people's living standards, the number of household appliances is increasing. In the process of using electricity, personal electric shock and fire accidents caused by defects in electrical equipment, improper use and unfavorable safety technical measures have brought undue losses to people's lives and property. The appearance of leakage protector provides a reliable and effective technical means for preventing all kinds of accidents, cutting off power supply in time and protecting equipment and personal safety.
5. What is the main cause of electric shock accident?
According to statistics, the main causes of electric shock accidents are as follows:
(1) Lack of electrical safety knowledge, flying kites near high-voltage lines and climbing high-voltage poles to dig out the bird's nest; After the low-voltage overhead line is disconnected, connect the fire line by hand without power failure; Touch the charged body by hand for live wiring at night; Touch the broken rubber knife switch with your hand.
(two) in violation of the operating rules, without taking necessary safety measures, unauthorized connection of lines or electrical equipment; Touch damaged equipment or wires; Wrong installation of live equipment; Electrified lighting; Online maintenance of power tools; Live mobile electrical equipment; Twist a light bulb, etc with wet hands.
(3) The equipment is unqualified and the safety distance is not enough; The grounding resistance of two-wire and one-ground system is too large; The grounding wire is unqualified or disconnected; Insulation damage, exposed wires, etc.
(4) The equipment is in disrepair, the line is blown off by strong wind or the pole is not repaired in time; Rubber breaker bakelite is damaged and not replaced in time; The damage of the motor lead makes the shell charged for a long time; The porcelain bottle is damaged, which makes the phase wire and the pull wire short-circuited, and the equipment shell is charged.
(5) Due to other accidental reasons, I walked at night and ran into a broken live wire on the ground.
6. What rescue measures should be taken in case of electric shock?
When an electric shock accident occurs, while ensuring the rescuer's own safety, we must first try to make the electric shock victim quickly get rid of the power supply, and then carry out the following emergency repair work.
(1) Untie the tight clothes that hinder the breathing of the electrocuted person.
(2) Check the mouth of the person who gets an electric shock and clean up the mucus in the mouth. If there are any dentures, remove them.
(3) immediately on-site rescue. If breathing stops, rescue with mouth-to-mouth artificial respiration. If the heart stops beating or vibrates irregularly, use artificial chest compression to rescue it. Never interrupt for no reason.
If there is a second person besides the rescuer at the scene, the following work should be done immediately:
1) Tools and equipment for providing first aid.
2) convince others at the scene.
3) Keep sufficient lighting and air circulation at the site.
4) Report to the leader and ask the doctor to come to the rescue.
Experimental research and statistics show that 90% patients can be saved if treatment is started from 1 min after electric shock. Only 10% chance can save lives if rescue is started 6 minutes after electric shock; But from 12 minutes after electric shock, the possibility of saving lives is extremely small. So if you find someone getting an electric shock, you should race against time and take all possible measures.
7. What measures are there to use electricity safely at home?
With the popularization and application of household appliances, it is very important to correctly master the knowledge of safe electricity use and ensure the safety of electricity use.
(1) Don't buy fake and shoddy "three noes" household products.
(2) When using household appliances, there should be a complete and reliable power cord plug. Household appliances with metal shell should be protected by grounding.
(3) Switches and fuses cannot be installed on the ground wire and zero wire. It is forbidden to connect the ground wire to the tap water and gas pipeline.
(4) Don't touch the live equipment with wet hands, and don't wipe the live equipment with wet cloth.
(5) Don't connect wires privately, and don't move live equipment casually.
(6) When repairing household appliances, you must first disconnect the power supply.
(7) When the power cord of household appliances is damaged, it should be replaced immediately or wrapped with insulating cloth.
(8) When household appliances or wires catch fire, disconnect the power supply first, and then put out the fire.
8. How to prevent burning household appliances?
The rated voltage of common household appliances is 220 volts, and the normal power supply voltage is around 220 volts. If the power supply voltage in the power supply line rises instantly due to natural disasters such as lightning strike, the zero line of the three-phase unbalanced household line is broken due to years of disrepair, or the phase voltage rises due to human misconnection, the current will increase, and household appliances will burn out due to overheating. To prevent the burning of household appliances, we should start from the following aspects: First, try to disconnect the power supply when the electrical equipment is not in use; The second is to transform the old and disrepair connecting lines; The third is to install a leakage switch with overvoltage protection.
9. How do households choose fuses?
Household fuses should be selected according to the size of the capacitor used. If an ammeter with a capacity of 5 A is used, the fuse should be greater than 6 A and less than10A; If an electric meter with a capacity of 10A is used, the fuse should be greater than 12A and less than 20A, that is, the selected fuse should be 1.2~2 times the capacity of the electric meter. The selected fuses should meet the requirements, not multiple fuses with small capacity, let alone copper wires instead of fuses.
10, what are the basic requirements of the leakage protector?
Technically, the following requirements should be met:
(1) The sensitivity of electric shock protection should be correct and reasonable, and the general starting current should be within the range of 15~30 mA.
(2) The action time of electric shock protection should generally not be greater than 0. 1 sec.
(3) The protector shall be equipped with necessary monitoring equipment to prevent it from losing its protection function when the running state changes. For voltage-type electric shock protectors, neutral grounding devices should be installed.
1 1. How to prevent electrical fire accidents? What should I do after a fire?
First of all, when installing electrical equipment, we must ensure the quality and meet the requirements of safety and fire prevention. Qualified electrical equipment should be used. Do not use broken switches, lamp holders and broken wires. Wire connectors shall be firmly connected according to the specified connection method and wrapped with insulating tape. Tighten the connection of the connection pile head and terminal to prevent poor contact caused by loose connection. After the electrician installs the equipment, it does not mean that it can be done once and for all. In the process of use, if users find that the wiring of lamp holder and socket is loose (especially the wiring of plug of mobile appliances is easy to be loose), the contact is poor or there is overheating, they should find an electrician to deal with it in time.
Secondly, do not place oil, cotton, sawdust, wood and other easily dyed items near low-voltage lines and switches, sockets and fuses.
Before an electrical fire, we should pay special attention to a precursor, that is, the wires will first burn the insulation sheath due to overheating, giving off an unpleasant smell of burnt rubber and burnt plastic. Therefore, when you smell this smell, you should first think that it may be caused by electrical reasons. If no other reason can be found, turn off the power immediately until the reason is found out and properly handled.
In the event of a fire, whether it is caused by electricity or not, we should first try to cut off the power supply in the fire area quickly. Because, if the fire is caused by electricity, cutting off the power supply will also cut off the fire source; If the fire is not caused by electricity, it will also burn out the insulation of the wire. If the power supply is not cut off, the burnt wire will cause a short circuit and cause a wider range of wires to catch fire. After an electrical fire, cover soil, sand or fire extinguisher should be used, but foam extinguisher should not be used, so this fire extinguishing agent is conductive.
12, common sense of household safety electricity use.
(1), every family should have some necessary electrical appliances, such as pencil, screwdriver, rubber pliers, etc. , but also must have various specifications of fuses and fuses suitable for the right to use household appliances.
(2), every household meter must be equipped with master insurance, and the meter should be equipped with master breaker and leakage protection switch.
(3) In any case, it is forbidden to use copper wire and iron wire instead of fuse. The size of the fuse must match the capacitance. When replacing the fuse, remove the porcelain box cover and replace it. It is not allowed to overlap the fuse directly in the porcelain box, and it is not allowed to replace the fuse with electricity (without opening the circuit breaker).
(4), fuse blowing or leakage switch action, must find out the reason to turn off the switching power supply. Under any circumstances, it is not allowed to use the short-circuit insurance of wires or the tripping mechanism of forced leakage switch to send electricity.
(5) When purchasing household appliances, carefully check the technical parameters (such as frequency, voltage, etc.). ) meet the local power consumption requirements. It is necessary to know how much electricity is used and whether the existing power supply capacity of the family meets the requirements, especially whether the wiring capacity, plugs, sockets, fuses and meters meet the requirements.
(6), when the household power distribution equipment can't meet the requirements of household appliances capacity, should be replaced, it is forbidden to make do with it. Otherwise, overload operation will damage electrical equipment and may also cause electrical fire.
(7) When buying household appliances, you should also know their insulation performance: general insulation, reinforced insulation or double insulation. If grounding is used for leakage protection, grounding wire is essential. Even for electrical equipment with reinforced insulation or double insulation, it is beneficial to do protective grounding or protective grounding.
(8) Household appliances with motors (such as electric fans, etc.). ), you should also know the heat resistance level and whether it runs continuously for a long time. Pay attention to the heat dissipation of household appliances.
(9) Before installing household appliances, you should check the requirements of the product manual for the installation environment, and pay special attention not to install household appliances in an environment with damp heat, dust or flammable, explosive and corrosive gases as much as possible.
(10), when wiring indoors, the phase line and the zero line should be clearly marked and consistent with the wiring of household appliances, and they should not be staggered.
(1 1), the connection between household appliances and power supply must use switches or plugs, and it is forbidden to directly insert wires into socket holes.
(12), all household appliances requiring protective grounding or safe zero connection should adopt three-pin plugs and three-pin sockets, and two-pin plugs and two-pin sockets are not allowed to be used instead, resulting in neutral grounding (or zero connection) wires.
(13), it is better to have no connector in the middle of home wiring. If there must be a joint, it should be firmly contacted, wrapped with insulating tape, or a porcelain junction box. Standard uses medical tape instead of electrical tape to wrap joints.
(14), wires and switches, circuit breakers, fuse boxes, lamp holders, etc. The connection is firm and reliable, and the contact is good. The multi-rubber flexible copper wire connector should be twisted first, and then placed under the connector screw gasket to prevent the thin strands from spreading and contacting another connector and causing short circuit.
(15), household wiring shall not be directly laid on flammable building materials, and porcelain beads or clamps must be used if wiring is needed on wood; Porcelain sleeves must be used to penetrate the board. Flammable plastics and other flammable materials shall not be used as decorative materials.
(16), the grounding or neutral line is normally not charged, but in case of leakage after disconnection, the shell of the right electrical appliance will be charged; In the case of short circuit, the grounding wire also passes a large current. For the sake of safety, the specification of the grounding (neutral) wire shall not be lower than that of the phase wire, and switches, fuses or connectors shall not be installed on it.
(17), the grounding wire should not be connected to the tap water pipe (because the tap water pipe joint is now sealed with insulating tape and has no grounding function); Do not connect it to the gas pipe (in case of gas explosion caused by electric spark); Don't connect it to the ground wire of the telephone line (in case of strong current and weak current); Nor shall it be connected to the down lead of lightning rod (to prevent lightning strike).
(18), all switches, knives and fuse boxes must be covered. Bakelite cover plate is aging and incomplete and must be replaced. Dirty and wet people must be wiped clean before use after power failure.
(19), the power cord should not be dragged on the ground to prevent the power cord from tripping and damaging the insulation.
(20) Before household appliances are tried out, all switches and buttons should be placed in the original stop position according to the requirements of the manual, and then the start-stop operation sequence required by the manual should be carried out. If there are moving parts, such as a head-shaking fan, sufficient motion space should be considered in advance.
(2 1), when household appliances are found to be sparking, smoking or burning after being electrified, stop immediately and cut off the power supply for inspection.
(22) When moving household appliances, be sure to cut off the power supply to prevent electric shock.
(23), around the heating appliance must be far away from flammable materials. Electric stove, heating stove, electric iron and other heating appliances should not be placed directly on the board to avoid fire.
(24), it is forbidden to touch the live switch with wet hands; It is forbidden to plug the power supply with wet hands; When unplugging the power plug, fingers must not touch the metal part of the contact; Never replace electrical components or light bulbs with wet hands.
(25) Used in household appliances (such as hair dryer, electric soldering iron, etc.). ) It is often used in your hands, and it is forbidden to wrap wires around your hands.
(26) Household appliances in contact with human body, such as electric blankets, electric oil caps, electric shoes, etc. Before use, it should be electrified for testing and inspection, and it can only touch the human body after there is no leakage.
(27) It is forbidden to move household appliances by dragging wires; It is forbidden to pull the plug by dragging the wire.
(28), when using household appliances, plug in the neutral end of the socket first, and finally close the knife switch or plug in the live end socket; On the contrary, when stopping the use of household appliances, first pull the circuit breaker on the live side or pull out the socket on the live side, and then pull out the socket on the dead side (if necessary).
(29) When it is necessary to cut off the power supply wire in an emergency, insulated electrician tongs or insulated handle cutters must be used.
(30), rescue electric shock personnel, first of all, to disconnect the power supply or use wood, insulating rod pick open the power cord, don't directly drag electric shock personnel by hand, so as to avoid serial electric shock.
(3 1), household appliances, except refrigerators, should be turned off at will, especially electrical appliances, to prevent fires caused by long-term heating.
(32), bed switch is strictly prohibited. Except for electric blankets, don't lead charged electrical equipment to the bed, close to the sleeping human body. Even if an electric blanket is used, it is recommended to turn off the power supply after heating to ensure safety if it is not necessary to keep warm all night.
(33), household appliances burning, smoking, fire, must immediately disconnect the power supply, shall not be sprayed with water or foam extinguisher.
(34), indoor wiring and electrical equipment insulation should be checked regularly, found that the damage should be promptly wrapped with electrical tape.
(35) The insulation resistance of household appliances that have not been used or reused for a long time before the rainy season should not be lower than1mΩ when measured with a 500V shaking table, which can be considered as good insulation and can be used normally. If there is no shaking table, at least use a test pen to regularly check whether there is any leakage.
(36) For household appliances that are often used, keep them dry and clean. Do not wipe the surface of household appliances with corrosive or conductive liquids such as gasoline, alcohol, soapy water and decontamination powder.
(37) After household appliances are damaged, please ask professionals or send them to a repair shop for repair; Non-professionals are strictly forbidden to open the shell of household appliances under live conditions.
Five, the principle of safe use of electricity
(1) Keep away from high-voltage charged bodies (outdoors, beside high-voltage lines and transformers) and avoid contact with low-voltage charged bodies. ?
(2) Insert or pull out the plug without using the wet manual switch. ?
(3) Installation and maintenance of electrical appliances should wear insulating shoes, stand on the insulator and cut off the power supply. ?
(4) It is forbidden to use copper wire instead of fuse and rubber instead of electrical insulation tape. ?
(5) Install an electric shock protector in the circuit and check its sensitivity regularly. ?
(6) Do not use the radio, video recorder and TV set in thunderstorm weather, and unplug the power plug and antenna plug of the TV set. Don't use the phone for the time being If you must use it, you can use the hands-free function. ?
(7) It is forbidden to connect wires without permission, and students are forbidden to use electric stoves, "quick heating" and other electrical appliances in the dormitory. ?
(8) Don't fly kites or play ball under telephone poles and wires.
Six, other matters needing attention
People's safe voltage is not higher than 36 volts.
Do not touch the metal rod of the nib with the electric probe.
High-power appliances must be grounded.
You can't connect the live wire and the ground wire with your body.
The total power of the electrical appliances used should not be too high, otherwise it will cause excessive current and cause fire.
Someone gets an electric shock, so you can't pull him with your body. Turn off the main switch immediately, and then use a dry wooden stick to separate people from the wires.