Every year, many buildings and electrical engineering suffer from the effects of lightning discharges. To protect structures from such natural phenomena, a lightning protection system should be installed.
Lightning protection in a private house is a set of measures and means that ensure the safe operation of a ground object during thunderstorms. This is a necessary attribute of any structure that provides protection of explosive, fire hazardous, technological, material values, as well as people from primary and secondary manifestations of lightning.
Features of choice
If there are no lightning protection devices on the structure, a lightning strike can cause a fire, destruction of the object or human damage.
The main device of a lightning rod is one, but they use various materials for construction. Choosing this design, the following parameters should be considered:
- Features of the construction structure.
- The intensity of the passage of thunderstorms for a year in a particular area.
- Desired degree of security.
Quality lightning protection
The calculation of lightning conductor zones should be based on information about the width, length and height of the building for which the protective structure will be constructed.
In addition, the average annual number of lightning strikes in a particular area should be taken into account.
During the design process, specialists independently calculate the protection zones of the structure. According to these data, lightning protection is being constructed. The calculation is simple, for this you can use many calculators on the network.
Purpose of the structure and lightning conductor
Thinking about protection from lightning, you should make a lightning protection project.
Today there are three types of lightning rods, which differ from each other by design features and operating requirements.
The first category includes facilities working with explosive chemicals and storing them. In such rooms, mixtures of dust, vapors and gases with air are constantly present. They represent a huge danger to human life.
The second category includes facilities in which explosive substances are stored in hermetically packed metal containers. In such conditions, only in an emergency can dangerous explosive mixtures occur, which consist of vapors, gases and dust with air. As a result of the explosion, the destruction will be partial.
The third category includes rooms in which explosive mixtures cannot form.
It should be remembered that the installation of lightning protection systems that prevent direct impacts, secondary impacts and drift of high potentials is necessary for structures that belong to the first and second categories. Buildings belonging to the third category require the installation of a lightning rod to prevent direct lightning strikes and high potential drift.
Kinds
Let's look at the example of a multi-storey building lightning protection device. It can be both external and internal. Each has a special purpose. Both the first and second species are very important. They ensure the safety of not only your property, but also the health of your loved ones.
External lightning protection in a private house is quite simple. It consists of the following elements:
- down conductor.
- Lightning rod.
- Earthing switch.
The interception of lightning directly above the roof, and after passing the charge through a safe channel and draining it to the ground - this is lightning protection. The calculation of the necessary materials for the construction of the structure should be given in the design documentation. Installation of the device can be carried out by each person independently.
But the circuit of the internal lightning rod is much more complicated. This is a whole range of measures that can ensure the safety of electrical appliances and wiring throughout the house. This work is best entrusted to specialists. After all, only they can correctly choose the necessary equipment for your home, which will help protect the room from damage.
Consider the functions of each element of the external lightning rod.
Down conductor
A down conductor is a specific conductor that connects the ground electrode and the air terminal to each other. For its manufacture, galvanized or black steel products with a diameter of more than 6 mm are used. This element is connected using a metal clamp with nuts and bolts by welding with grounding. It must be laid in such a way that there is as little distance as possible between the air terminal and the ground electrode. The outer part of this element must be accessible. This eliminates the possibility of attenuating damage or pulling the collector.
A down conductor can also be metal elements of a structure (pipes, fire escapes , etc.). The main thing is that a reliable electrical contact occurs between all elements of the lightning protection system.
Lightning rod
The air terminal is designed to intercept an electrical discharge. Its role can be performed by a metal mesh, rod or cable.
A metal air terminal in the form of a grid is installed directly on the roof of the building. For the manufacture of this element using rolled steel with a circular cross section or strip of this material. If you decide to install an air terminal of this type, then you should create conditions for the continuous cleaning of ice or snow from the roof. You also need to take care of unhindered rainfall. In no case should the liquid remain on this part of the structure. The maximum cell size is 5 x 5 m.
A metal rod air terminal is traditional for our country. It began to be used in the 18th century. Most often it is installed in private homes. Fix the rod on the roof. It is made of profile metal.
The lightning rod in the form of a cable has the form of a metal rope, which is suspended on supporting structures. Horizontal lightning rods are located on two grounded supports. Most often they are installed on technical structures, which are characterized by a considerable length (overhead power lines). This type is very rarely used to protect buildings from lightning strikes.
Lightning protection of structures directly depends on this element of the system.
Earthing switch
It is a metal conductor, which must necessarily come into contact with the soil. Most often, metal products act as a ground electrode system: an angular profile, a strip or a pipe.
The manufacture of a lightning conductor with its own hands allows the use of sub-standard or used gas or water pipes. Remember that the ground electrode must be cleaned from corrosion. The best option is to use galvanization. If people are near the ground during a thunderstorm, then its resistance should not exceed 10 ohms.
Project
Before proceeding with the construction, a lightning protection project should be created. It is better to entrust it to specialists. The project should provide for the construction of a lightning conductor of a structure, taking into account its main purpose, that is, a category. For example, a residential building belongs to the III category.
The following must be indicated in the project:
- Type of air terminal (what material is made of, cell pitch).
- Features of the down conductor (of which it is made, wire diameter, method of attachment to the air terminal, grounding).
- Features of grounding (place, depth of location, from what material it is made).
Lightning conductor mounting
Choose the highest point on the roof. Here you need to fix the mast on which the air terminal will be installed. Its height is controversial even among experts. Some argue that tall masts can catch lightning that could bypass the house. Others believe that the higher it is, the better lightning protection will be. They do not calculate the height of the air terminal, since this issue is controversial. Therefore, experts do not indicate the exact length of the mast.
It is better to make a mast from a wooden bar. The air terminal should be firmly fixed to the top of the mast. Most often, for these purposes, use tightly tightened metal clamps.
A conductor should be connected to the air terminal. It is attached to the mast with plastic clamps. A cable is often used as a conductor, which is easy to pass down the drain. So you can protect it from gusts of wind, ice and snow.
Lightning protection and grounding are closely related to each other. After all, it is the correct location of the last element that contributes to the safe removal of electric charge.
At a distance of 3 meters from the house, dig a hole. It is better to choose a place where people rarely go and cars do not stand. The depth of the pit depends on the level of groundwater. It is advisable to lay the ground rods in moist ground. An earthing switch is laid in the dug hole, to which a down conductor is attached. After the hole is carefully buried.