Views: 5157 Author: Site Editor Publish Time: 2020-05-11 Origin: Site
Because the metal case of some appliances can conduct electricity, in order to prevent electric shock, another wire is usually connected to the ground, which is the ground wire. The ground line can also be called a safety circuit line, and the voltage difference between the ground line and the zero line is 0V. Generally speaking, a certain socket is not equipped with a ground wire, and an electric shock will occur when the outer casing of the appliance is metal, such as a microwave oven. When electrical leakage occurs, the current will pass the high voltage to the ground through the ground wire, thereby avoiding electric shock to the human body, so it is also regarded as a "life safety line". By connecting the ground wire, you can prevent the electrical equipment shell from being charged in the case of leakage of electrical appliances at home. In other words, the ground wire plays a role of safety protection. In addition, because the domestic voltage is 220V, it is easy to generate static electricity. Grounding can also transfer static electricity, reducing the possibility of family electric shock. Therefore, the home socket (three-hole plug) is essential to the ground wire! Even to prevent breakage, repeated installation is required. This will ensure the safety of household electricity.
The sole function of the ground wire is to prevent the electrical housing from being charged. One end of the ground wire is connected to the electrical housing through a three-pin plug, and the other end is connected to the ground through a grounding body. It can keep the electrical potential on the enclosure of the appliance always the same as the ground-zero. People stand on the ground, so the potential on people is zero. We make the electrical potential on the electrical appliance shell always zero. The ultimate goal is to prevent the electrical potential difference between the electrical appliance shell and the human body, so that no current can be generated, and people will naturally not be electrocuted.
Normally, the potential on the appliance shell is zero, so we don't get an electric shock when we touch it. What causes the potential on the electrical enclosure to be non-zero?
There are two common reasons:
1. Electrical leakage. The potential on the internal circuit of the appliance is not zero, otherwise how can it produce a current? Once the insulation layer of the line is damaged, the potential on the electrical enclosure will be changed so that it is not zero.
2. Induction electricity. There are conductors in the line, which are metallic; the casing is also metallic. If two metals are placed in parallel with an insulating medium in between-this device is called a "capacitor". Of course, whether such a capacitor can generate current depends on the conductivity of the medium. Once the insulation layer is aged or the line is too close to the case, it will induce electricity.
After the electrical potential of the electrical enclosure rises, it can not be reduced to zero in time, resulting in electric shock to the human body (not only harmful to the human body, but also the equipment may be burned).
However, there are two issues to note:
1. All the shells that may be charged are absolutely metal, so we see electrical appliances that are connected to the ground wire (use a three-pin plug to indicate that the appliance is connected to the ground wire), and its housing definitely has metal parts.
2. The ground wire can only prevent the electric shock through the shell. As for other electric shock methods, such as electric shock by contacting the line, electric shock through the air, etc., the ground wire cannot provide protection.
Through the above knowledge, we know that household electrical outlets are not grounded. When using electrical appliances, although they generally do not affect the use of electrical appliances, there will be hidden safety hazards. Once the electrical leakage inside the electrical appliances, it will threaten personal safety. Therefore, the household outlet must be connected to the ground wire.
At present, the household appliances with metal shells generally have three-pin plugs. This is designed by the manufacturer to protect the safety of consumers. The electrical appliances of this plug must be properly grounded. The two-pin plug appliances generally do not need to be grounded, which is determined by their shell technology and internal circuits.
We should correctly introduce the ground wire into the socket to avoid safety accidents. Furthermore, if there is no ground wire in the countryside or low-rise buildings of our own, we should bury the ground wire ourselves (dig a two-meter hole or pit in the ground , buried metal objects, if the pit is less than two meters, you can sprinkle a few packets of salt around the metal objects, add charcoal and add water to reduce the ground resistance) and then connect the ground wire to the room. There is no ground wire in the socket in the home, you can pull a wire on the protective ground of the socket and connect it to the heating pipe and water pipe. If it is convenient to install the ground wire in the bungalow or out of the room, you can choose a relatively humid ground and smash one. The iron rod goes underground to be used as a ground wire.
When the earth leakage circuit breaker is not used in the home decoration, the power outlet is required to be properly equipped with a ground wire. In recent years, the earth leakage circuit breaker has been used in the home decoration. The correct configuration is to install a two-pole main circuit breaker into the household line. One way is for lighting, the other way is for the socket. There is no earth leakage circuit breaker for lighting. The earth socket must be reasonably configured with earth leakage circuit breaker. But it may increase the probability of circuit breaker operation, that is, this leakage current is not a protection action due to human body flow. If the earth leakage circuit breaker is sensitive but does not have a ground wire, when an earth leakage current flows through the human body, the earth leakage circuit breaker will operate without personal injury. As long as there is no problem with the earth leakage circuit breaker, no ground wire is also safe, regardless of the ground wire.
Electricity safety is the most basic common sense in the home, but for laymen, they often pay little attention to it. As a result, these people will be accidentally charged by the casing when using electrical appliances. In fact, this is caused by not installing a ground wire. There is no ground wire in the socket at home. Of course, the ground wire must be used or the above methods can be used to prevent electric shock!