Safety knowledge

1. Why must the lighting switch be connected to the fire?

If the light switch is installed on the zero line, although the light does not turn on when the light is turned off, the phase line of the light head is still turned on, and people think that the light is off, they will erroneously think that it is in a power-off state. In fact, the ground voltage at each point on the luminaire is still a dangerous voltage of 220 volts. If people touch these actually live parts when the lamp is off, it will cause electric shock. Therefore, the switches of various lighting switches or single-phase small-capacity electrical equipment can only be secured if they are connected in series to the fire line.

2. How to install the single-phase three-hole socket correctly? why?

In general, single-phase electrical equipment, especially portable electrical equipment, should use three-pin plugs and matching three-hole sockets. There is a special protection zero (ground) jack on the three-hole socket. When the zero protection is used, someone often directly connects the hole in the bottom of the socket with the neutral line in the introduction socket. This is Extremely dangerous. Because if the zero line of the power supply is disconnected, or if the power (phase) line and neutral line of the power supply are reversed, the metal parts such as the housing will also carry the same voltage as the power supply, which will result in electric shock.

Therefore, the dedicated ground jack should be connected to the dedicated protective grounding wire when wiring. When using zero protection, the zero line should be specifically drawn from the power supply, instead of using the zero line introduced into the nearest outlet.

3. Why are plastic insulated conductors forbidden to be directly buried in the wall?

(1) After plastic insulated wire is used for a long time, the plastic will be aged and cracked, and the insulation level will be greatly reduced. When the circuit is overloaded or short-circuited for a short time, it is easier to accelerate the insulation damage.

(2) Once the wall is wet, it will cause a large area of ​​electricity leakage, endangering personal safety.

(3) Directly buried plastic insulated wire is not conducive to line inspection and maintenance.

4. Why use a leakage protector?

Leakage protector, also known as leakage protection switch, is a new type of electrical safety device, its main purpose is:

(1) Prevent electric shock caused by leakage of electrical equipment and electrical lines.

(2) Prevent single-phase electric shock in the process of electricity use.

(3) The single-phase earth fault in the operation of the electrical equipment is cut off in time to prevent electrical fire accidents caused by electrical leakage.

(4) With the improvement of people's living standards, the number of household appliances is increasing, and in the process of electricity use, due to the defects of the electrical equipment itself, improper use, and unsafe technical measures, the person's body is exposed to electric shock and fire accidents, giving life to the people. And the property has brought undue losses, and the emergence of leakage protection devices, to prevent the occurrence of various types of accidents, cut off power in a timely manner, protect equipment and personal safety, provide a reliable and effective technical means.

5. What are the main causes of electric shock?

Statistics show that the main causes of electrocution accidents are the following:

(1) Lack of electrical safety knowledge, flying a kite near high-voltage lines, climbing high-voltage poles and gnawing the bird's nest; after low-voltage overhead lines are disconnected, they will continue to use their hands to pick up the fire line; the night-time electrified wiring hand touches live bodies; Plastic cover cutter.

(2) Violation of operating procedures, electrification of wiring or electrical equipment without taking necessary safety measures, touching damaged equipment or wires, mischarging charged equipment, lighting fixtures with electricity connected, repairing power tools with live charging, and electrifying mobile electrical equipment; Wet hand bulbs and so on.

(3) The equipment is unqualified, the safety distance is not enough; the grounding resistance of the second-wire system is too large; the grounding wire is unqualified or the grounding wire is disconnected; the insulation damage conductor is exposed to the outside and so on.

(4) The equipment is in disrepair, the wind blows off the circuit or the pole is not repaired in time; the bakelite damage of the plastic cover switch is not changed in time; the motor wire is broken and the shell is charged for a long time; the porcelain bottle is destroyed and the phase wire and the pull wire are shorted. The device housing is charged.

(5) For other accidental reasons, the nighttime walking touches live conductors that have fallen off the ground.

6. What rescue measures should be taken when an electric shock occurs?

In the event of an electric shock, while ensuring the safety of the ambulance itself, it is necessary to first try to get the electric shocker out of the power quickly, and then perform the following repair work.

(1) Untighten tight clothing that prevents the electric shocker from breathing.

(2) Check the mouth of the person who has received the electric shock and clean up the mucus in the mouth. If there is any denture, remove it.

(3) Immediately on-site rescue, such as respiratory arrest, using mouth-to-mouth artificial respiration rescue, if the heart stops beating or irregular tremors, artificial chest compression can be rescued. It must not be interrupted without reason.

If a second person is present in addition to the rescuer at the scene, the following work should also be carried out immediately:

1) Provide tools and equipment for first aid.

2) Dismiss the casual staff at the scene.

3) Keep enough lighting on site and maintain air circulation.

4) Report to the leader and ask the doctor to come to the rescue.

Experimental studies and statistics show that 90% of people can be saved if treatment is started 1 minute after an electric shock, and only 10% of them are saved if they are rescued from 6 minutes after an electric shock, and emergency rescue is started 12 minutes after an electric shock. The possibility of survival is minimal. Therefore, when someone is found to have an electric shock, they should fight against the seconds and use all possible methods.

7. What measures do household safety use?

With the popularization and application of household appliances, it is very important to correctly grasp the knowledge of safe use of electricity and ensure the safety of electricity.

(1) Do not buy "three no" fake and shoddy household products.

(2) When using home appliances, there should be a complete and reliable power cord plug. Home appliances for metal enclosures must be grounded.

(3) Switches and fuses cannot be installed on the ground and neutral wires. It is forbidden to connect the grounding cable to tap water and gas pipelines.

(4) Do not touch the live device with wet hands, and do not wipe the live device with a damp cloth.

(5) Do not pull the cable and do not move the charged device.

(6) When checking and repairing home appliances, the power must be turned off.

(7) When the power cord of the household appliance is damaged, immediately replace it or wrap it with an insulating cloth.

(8) When there is a fire in a household appliance or wire, disconnect the power supply and then extinguish the fire.

8, how to prevent the burning of household appliances?

The rated voltage of commonly used household appliances is 220 volts, and the normal supply voltage is around 220 volts. When the power supply voltage is instantaneously increased due to a lightning strike or other natural disaster in the power supply line, the zero-phase fault occurs when the three-phase load is unbalanced, or the voltage rises due to phase voltage rise caused by human error wiring. As a result, the current increases causing the household appliance to burn due to overheating. To prevent the burning of household appliances, it is necessary to start from the following aspects: First, when the power equipment is not used, it should be disconnected as much as possible; second, transform the old and unrepaired receiver line; third, install an over-voltage protection leakage switch.

9, how to match the household fuse?

Household fuses should be selected based on the size of the capacity used. If a meter with a capacity of 5 A is used, the fuse shall be greater than 6 A and less than 10 A; if a meter with a capacity of 10 A is used, the fuse shall be greater than 12 A and less than 20 A. That is, the selected fuse shall be 1.2 - 1 of the meter capacity. 2 times. The selected fuse should be one that complies with the regulations. It cannot use multiple fuses with small-capacity fuses. It cannot use copper wires instead of fuses.

10. What are the basic requirements for a leakage protector?

Technically it should meet the following requirements:

(1) The sensitivity of the electric shock protection must be correct and reasonable. The general starting current should be within the range of 15 to 30 milliamperes.

(2) The operating time for electric shock protection should not exceed 0.1 second under normal circumstances.

(3) The protector shall be equipped with necessary monitoring equipment to prevent loss of protection when the operating state changes. For a voltage type electric shock protector, a neutral grounding device shall be installed.

11. How to prevent electrical fire accidents? What happens after a fire?

First of all, when installing electrical equipment, quality must be ensured and all requirements for safe fire protection should be met. Use qualified electrical equipment. Damaged switches, lamp caps, and broken wires must not be used. Wire connections must be securely connected and secured with insulating tape. Wiring the wiring pile heads and terminals must be tightened to prevent poor contact due to loose wiring. After the electrician installs the equipment, it does not mean that it can be done once and for all. If the user finds that the lamp and the socket are loosely connected (especially the mobile electrical plug is easy to loose), the contact is bad or there is overheating, and the electrician needs to deal with it in time. .

Second, don't place oil, cotton, sawdust, wood, and other contaminated items near the low-voltage lines, switches, sockets, and fuses.

Before the electric fire, there is a kind of precursor. Special attention should be paid to the fact that the electric wire will scorch the insulation sheath first because of overheating, and emit a bad smell that burns rubber and burns plastic. Therefore, when you smell this odor, you should first think that it may be caused by electrical reasons. If you do not find any other reason, you should immediately switch off the power until you find out the reason and handle it properly before switching on.

In case of a fire, whether it is caused by electricity or not, first of all, we must think of ways to quickly cut off the power within the scope of the fire. Because if the fire is caused by electricity, the power supply is cut off and the fire source is cut off. If the fire is not caused by electricity, the insulation of the wire will be burned. If the power is not cut off, the burned wire will cause damage. A short circuit to the touch causes a wider range of wires to catch fire. In the event of an electrical fire, cover soil, cover sand or fire extinguishers should be used, but foam fire extinguishers must not be used, so the extinguishing agent is electrically conductive.

12, household safety electricity knowledge

(1) Every family must have some necessary electrical appliances such as electroscopes, screwdrivers, and glue clamps, as well as various types of fuses and fuses that are suitable for the use of household appliances.

(2) Each household meter must be equipped with general insurance before it. The meter should be equipped with a total knife gate and leakage protection switch.

(3) In any case, it is forbidden to use copper or iron wires instead of fuses. The size of the fuse must match the capacity used. When replacing the fuse, remove the porcelain cover and replace it. Do not lap the fuse directly inside the porcelain case. Do not replace the fuse in the live condition (without opening the knife).

(4) After the fuse or leakage switch is blown, the cause must be ascertained before switching on the switching power supply. Under no circumstances shall the conductors be short-circuited or pressed against the leakage switch tripping mechanism for forced transmission.

(5) When purchasing home appliances, you should carefully check whether the technical parameters (such as frequency, voltage, etc.) of the product specification are in line with local electricity requirements. It is necessary to know how much power is consumed and whether the existing power supply capability of the family satisfies the requirements, especially whether the wiring capacity, plugs, sockets, fuses, and meters meet the requirements.

(6) When the household power distribution equipment cannot meet the capacity requirements of the household appliances, it should be replaced and modified. It is forbidden to make use of it. Otherwise, overloaded operation can damage electrical equipment and may cause electrical fire.

(7) It is also necessary to understand the insulation properties of household appliances: whether they are general insulation, reinforced insulation or double insulation. If it is grounded for leakage protection, the grounding line is essential. Even for reinforced or double-insulated electrical equipment, it is beneficial to provide protective grounding or zero protection.

(8) Household appliances with electric motors (such as electric fans, etc.) should also be aware of the heat-resistant level and whether they should be operated continuously for a long time. Pay attention to the heat dissipation conditions of household appliances.

(9) Before installing household appliances, check the requirements of the product specification for the installation environment. Pay particular attention to the possibility of not installing the household appliances in a hot, dusty or flammable, explosive, corrosive gas environment under possible conditions. .

(10) When laying indoor wiring, the phase line and neutral line should be clearly marked and consistent with the wiring of household appliances.

(11) If the household appliance is connected to a power source, a switch or plug connector that can be switched off must be used. It is forbidden to insert the wire directly into the socket hole.

(12) For household appliances that require protective earthing or zero-crossing protection, three-pin plugs and three-eye sockets shall be used. Do not use two-pin plugs and two-eye sockets instead, resulting in a grounded (or zeroed) line gap.

(13) There is no joint in the middle of home wiring. When there must be a connector, it should be in firm contact and wrapped with insulating tape, or a porcelain junction box. Standard medical tape instead of electrical tape dressing joints.

(14) The connection between the wire and switch, knife gate, fuse box, lamp cap, etc. shall be firm and reliable, and the contact is good. The soft plastic copper wire connector shall be twisted and then placed under the joint screw gasket to prevent the thin strands from being scattered and causing a short circuit on the other joint.

(15) Home wiring shall not be laid directly on the flammable building materials. For the wiring of wood, porcelain beads or porcelain clips must be used; ceramic casing must be used to pass through the wood. Do not use flammable plastics and other flammable materials as decorative materials.

(16), grounding or connecting the zero line is not charged when normal, but leakage in case of leakage will cause energized electrical enclosure shell; in the event of a short circuit, the grounding line also passes a large current. For its safety, the grounding (connected to zero) wire shall not be less than the phase conductor, and no switches or fuses may be installed on it.

(17) The grounding wire should not be connected to the water pipe (because the plugging of the tap water pipe is now using insulation tape, there is no grounding effect); it must not be connected to the gas pipe (to prevent sparks caused by the gas explosion); On the ground of the telephone line (in order to prevent weak electricity); also must not be connected to the lead line of the lightning conductor (to prevent counterattack when lightning).

(18) All switches, switches and fuse boxes must have a cover. Aging and incomplete parts of the bakelite cover must be replaced. Dirty and damp persons must be wiped clean after use.

(19) Do not drag and drop the power cord on the ground to prevent the power cord from coming off and prevent damage to the insulation.

(20), before the trial of household appliances should be compared with the instructions, all switches, buttons are placed in the original stop position, and then follow the instructions to start and stop the operation sequence. If there are moving parts such as a moving head fan, consider sufficient space for movement in advance.

(21) When an abnormal condition such as spark, smoke, or burnt smell is found after the household appliance is energized, it shall immediately stop and cut off the power supply for inspection.

(22) When moving home appliances, be sure to cut off the power supply to prevent electric shock.

(23) Heat-emitting appliances must be kept away from flammable materials. Electric stoves, heating appliances such as heaters, irons, etc. must not be placed directly on the boards to avoid fire.

(24) Do not touch the live switch with wet hands; do not pull or plug the power plug with wet hands; do not touch the metal part of the contacts when pulling or inserting the power plug; or replace the electrical components or bulbs with wet hands.

(25) For household appliances that are frequently used by hand (such as hair dryers, electric irons, etc.), never use electric wires around the hands.

(26) For household appliances that are in contact with the human body, such as electric blankets, electric oil caps, and electric heating shoes, electric test should be conducted before use. It is only after contact with the human body that there is no leakage of electricity.

(27) It is forbidden to move the household appliances by dragging the wires; it is forbidden to use the method of dragging the wires to pull the plug.

(28) When using household electrical appliances, first insert the unpowered side socket, and finally close the knife or plug in the live side socket; on the contrary, if you disable the home appliance, first open the charged side knife or pull out the charged side. Socket, and then unplug the uncharged side of the outlet (if you need to pull out).

(29) In the event of an emergency requiring the disconnection of the power conductor, an insulated electrician's pliers or a knife with an insulated handle must be used.

(30) When rescuing a person with electric shock, first disconnect the power supply or use a wooden board or insulation rod to pick up the power cord. Do not pull the electric shocker directly by hand to avoid electric shock.

(31) In addition to household appliances such as refrigerators, household appliances should be turned off, especially electric heating appliances, to prevent long-term heating caused by fire.

(32) It is forbidden to use the bed switch. In addition to electric blankets, do not bring charged electrical equipment to your bed and stay close to your sleeping body. Even if the electric blanket is used, if it is not necessary to keep it warm for the whole night, it is recommended to use it after heating to ensure safety.

(33) Household appliances should be burnt, smoked, and caught on fire. They must be disconnected immediately and must not be sprayed with water or a foam fire extinguisher.

(34) Conduct regular insulation inspections on indoor wiring and electrical equipment and find that the damage is timely wrapped with electrical tape.

(35) Household appliances that are not used again before the rainy season or for a long period of time shall be measured for insulation resistance with a 500V megger so that the insulation resistance is not less than 1 MΩ. If no shaking, at least the application of electroscope to check for leakage.

(36) For household appliances that are frequently used, they should be kept dry and clean. Do not wipe the surfaces of household appliances with corrosive or conductive liquids such as gasoline, alcohol, soap and water, and decontamination powder.

(37) After a home appliance is damaged, a professional or a repair shop is required to repair it; non-professionals are prohibited from opening the housing of the home appliance when the power is on.