Views:94 Author:Site Editor Publish Time: 2019-11-03 Origin:Site
In thunderstorm weather, when charged clouds appear over tall buildings, lightning rod and the top of tall building are induced a lot of charge. Because the needle of the lightning rod is pointed, the tip of conductor always accumulates the most charge when induced by static electricity. In this way, the lightning rod aggregates most of the charge. The lightning rod forms a capacitor with these charged clouds. Because it is sharp, that is, the positive facing area of the cathode plate of the capacitor is very small, the capacitance is very small, and it can hold very little charge. And it accumulates a lot of charge, so when there's a lot of charge on the cloud, the air between the lightning rod and the cloud is easy to break through and become a conductor. In this way, the charged clouds form a path with the lightning rod. The lightning rod is grounding, and the lightning rod can introduce the charge on the cloud into the earth, so that the charge does not pose a danger to the high-rise building and ensures the safety of the building.
According to statistics, more than 4000 people around the world are hit by lightning every year. If the world population is calculated at 7 billion, the average probability of lightning strikes per person is about 1/1750000. According to the Federal Emergency response Administration, the average probability of lightning strikes in the United States is 1/600000. Thus it can be seen that the probability of lightning strike for everyone is not very large.
If you live in a building, you don't have to worry about the lightning strike, most of which are equipped with a lightning rod. However, some old buildings may not have lightning rod installed, so it is necessary to install lightning rod. Generally speaking, lightning rod is installed on the roof of the building.
If you live in a bungalow or a separate house, surrounded by big trees, or if around the house is flat and your house stands out, it is necessary to install lightning rod.
The lightning arrester is arranged at the part where the building is easy to be subjected to lightning stroke. In order to improve the reliability and safety, facilitate the dispersion of lightning current and reduce the lightning current flowing through the lead line, all lightning arresters should be connected to each other with lightning belts. The downlead should not be less than two and arranged evenly or symmetrically around the building. The impulse earthed resistance of each downlead shall not be greater than 10Ω. Install power arrester at power supply home. Install signal arrester at cable TV antenna, telephone, fax machine, computer modem entrance, satellite TV cable interface. But do a good job of grounding grid when installing.