What Are Mine Caps?

Lightning protection ^[1] refers to avoiding the harm to the human body and buildings caused by lightning through certain methods and measures. Lightning is a natural discharge phenomenon. Lightning strikes are natural disasters that will not only cause damage to equipment and house facilities, but also cause fires, explosions, and even harm people and animals. Lightning rods, lines, nets, belts, and arresters are all lightning protection devices often used. A complete set of avoidance devices includes air-termination, down-conductor and grounding devices. The above-mentioned needles, wires, nets and belts are all just air-termination devices, and the lightning arrester is a special lightning protection device. The causes, types, hazards, and lightning protection measures, devices, misunderstandings, and personal lightning protection are introduced in detail.

In a cumulonimbus cloud generated and charged by thunder and lightning, when positive and negative charges accumulate in different parts of the same cloud body or in different clouds, respectively, due to the difference in the amount of accumulated charges in different parts of the same thunderstorm or between different clouds, The polarity is different, and an atmospheric electric field is generated. When the strength of the atmospheric electric field can penetrate the air, a strong discharge phenomenon occurs, and lightning occurs ^.

There are four main types of lightning discharges: lightning in clouds, inter-cloud lightning, cloud-space lightning, and cloud-ground lightning. Among them, cloud-ground lightning is the most dangerous to humans ^[3]

The dangers of lightning include three aspects ^[3]

The first thing that needs to be explained is that the word "lightning protection" is wrong in modern lightning protection technology, and it is a misunderstanding. At least under modern science and technology, lightning protection cannot be truly achieved. Although scientists can change the formation time and lightning strike of lightning through lasers and rockets, they are currently limited to scientific research and cannot be widely used.

Aiming at the harm of lightning, lightning protection measures are divided into external lightning protection measures and internal lightning protection measures ^[4]

Lightning rods, lines, nets, belts, and arresters are all lightning protection devices often used. A complete set of avoidance devices includes air-termination, down-conductor and grounding devices. The above-mentioned needles, wires, nets, and belts are just lightning arresters, and the lightning arrester is a special lightning arrester ^[5]

During a thunderstorm, as the charged cumulus cloud directly discharges to the human body, the lightning current entering the ground generates a voltage to ground, and the secondary discharge can cause fatal electric shock to people. Therefore, attention should be paid to the necessary personal lightning protection safety requirements.

During a thunderstorm, it is not necessary to work, and you should minimize your stay outdoors or in the wild; it is best to wear plastic and other rain-proof raincoats in the outdoors or in the wild. If possible, you can enter buildings, cars or ships with large metal frames or lightning protection facilities; if you rely on sheltered streets or tall trees, you should leave the wall or trunk 8m away.

During a thunderstorm, you should try to leave the hills, hills, and bulging trails, and leave the seashore, lakeshore, riverside, and ponds, avoid barbed wire, metal clothesline, and flagpoles, chimneys, pagodas, and lonely trees. Small buildings or other facilities without lightning protection.

During a thunderstorm, you should pay attention to the danger of lightning intrusion indoors. You should leave the lighting line, power line, telephone line, broadcast line, radio and television power lines, radio and television antennas, and various metal equipment connected to them. In order to prevent these circuits or equipment from discharging to the human body. Survey data show that more than 70% of secondary discharges to the human body occur indoors within 1m of the line or equipment, and no fatal accident has occurred at distances of 1.5m or more. It can be seen that during a thunderstorm, the human body is better than 1.5m away from the lines and equipment that may transmit intruding waves of lightning. It should be noted that simply turning on the switch will not do much to prevent lightning strikes.

During thunderstorms, you should also pay attention to closing doors and windows to prevent ball thunder from entering indoors and causing harm.