In the context of global warming, abnormal changes in the weather occur every day. Increasingly, the rains will grow into a thunderstorm, accompanied by abundant lightning, and this happens not only in May, as he wrote the great sings, but throughout the calendar year. This circumstance determines the need for lightning protection of the roof in both private construction and industrial facilities.

What roofs attract lightning

To begin with, we will understand what a lightning strike is. Earth is a perfect grounding, so zipper cannot hit the ground object. The process is happening like this:

• in the clouds, an electric charge is formed, which rushes towards the Earth,
• the ground object is the source of the plasma beam, called the leader,
• the leader is a combination of preheated gases,
• the plasma beam is pulled up at a distance from 1-2 to several tens of meters,
• at the point of contact of the leader and lightning takes place.

In practice, this phenomenon is not studied, as it is mortally for life. In matters of lightning protection, the roof is guided by the general laws of physics. Theoretically, the only way to create perfect lightning protection is to build a plastic dome without a single metal object on the roof and in the whole house. But in practice, this solution cannot be applied.

Now consider in detail the most common types of roof:

• professional flooring
• slate,
• bituminous tile
• clay tile
• "Live" roof

By itself, professional flooring is an excellent insulator. But, the thickness of such a coating ranges from 2 to 5 mm, given the power of stress in lightning, this thickness is not enough to insulate the roof. In addition, the mount is carried out using metal screws, which serve as a binder bridge between the leader and lightning.

All the same is true to the sector, although in itself it does not conduct electricity, but the insufficient thickness and use of metal fasteners leads to a deterioration in lightning protection.

Tile is much thicker, but it has air gaps that are formed in the locations of the layers. Through these air layers, the leader is even easier than through metal and slate.

Although the roofs of the turf and chernozema should give good grounding, in practice it is not. During the rain, the soil wets, and through moisture it is possible to communicate lightning and leader. This type of roof is the most dangerous, although in frame wooden houses, in which there are no metal pipes, batteries and any other massive structures from iron, "live" roof itself serves as lightning protection.

Thus, the material does not matter, and the lightning protection of buildings with metal roofing does not differ from other types of roofing material.

Lightning protection technology

According to the principle of operation, allocate:

• active lightning protection
• passive lightning protection
• combined.

Even before the discovery of physical laws, people have noticed that lightning beats at the highest point on the ground. This served as the basis for the introduction of active lightning protection of the pitched roof. Metallic spiers of a certain length were installed on the buildings, which themselves had to attract lightning and take the main blow from the roof.

With the development of the laws of electrodynamics, this method has lost the relevance, as a scientific explanation of the phenomenon was found. In fact, the spire serves as a guide for the leader, but in practice, far from always the leader arises on the spire. In addition, arising in the area of \u200b\u200bthe spire, the leader can shift the emphasis in any direction, then the spire will really attract lightning, but it will hit the roof directly.

To date, the normative method is enshrined only in France and Kazakhstan, European countries, Russia and the United States adhere to passive protection. She is divided into:

• use metal mesh,
• use of metal sheets,
• using the whole roof
• special technical devices.

Recall once again that the reason for the occurrence of lightning is the difference in potentials that occurs between gases forming the clouds and a specific ground object. It is absolutely not necessary that this difference will arise between your home and thunderstorm clouds. This circumstance is based on passive protection. It is impossible to fully insulate any roof, but preventive measures must be taken.

Passive lightning protection is a high-quality grounding of the roof, or its individual elements. Grounding does not guarantee complete lightning protection, but if the leader arises on the roof, the electrical discharge will be stopped before penetrating the attic.

Special tools are technological devices that make grounding more efficient and protect the electrical appliances from the voltage drop caused by a lightning strike.

In order to have an idea of \u200b\u200bhow the lightning protection of the roof looks like, look at the photo.

Installation of lightning protection

Passive protection has several embodiments. For concretization, consider each of them for example:

• lightning protection of the roof of metal tile
• lightning protection of dielectric roofing,
• lightning protection of flat roof.

Lightning protection of the metal roof provides the richest choice of methods. The easiest, of which, is a complete grounding of the roof. To do this, you need to attach to the roof of two wires for each slope and lower them into the ground. Wires must be in isolation, which is suitable for a metal-plastic pipe. The ends of the wire should be cleaned and insert into the ground by 1.5-2 m for single-storey houses, 3-5 for two or more floors. The deeper, the better.

Such grounding will provide the minimum power of the leader, even if it arises, the electric current will instantly move from the roof on the wires and then to the ground. When choosing wires, it is important to remember that the power of zipper from 10,000 V, to 100,000 V, so the wires need to be taken with the calculation of this voltage. If it is not possible to find a cable with a corresponding cross section, then more thinned wires are used. Mounting wires can be used both with crocodiles and welding.

The professional flooring is covered with a special protective layer, which serves as a metal insulation. Naturally, it does not allow one hundred percent protection, but you can specify the places in which the leader arises.

It is important to understand that this option is suitable only if there is a layer of non-combustible materials between the metal sheet and wooden floors. When the lightning strikes at a particular point, iron melts and its drops can cause fire. Therefore, the first thing after the lightning strike, go and check the attic for the fire.

For these purposes, additional metal structures are installed on the roof, with a thickness of at least 10 mm, ideally, to create a critical mass, the thickness of the trap must be 4 times larger than the thickness of the metal tile.

The trap is useless, considering the current strength concentrated at a particular point, any wires are melted. Therefore, the grounding is carried out directly through the roof.

The sadder size of at least 80x80 cm. Optimally installed on 1 trap for every 10 kV. m roofing. Also, like a metal tile, the trap is melted from direct strike, but the drops will be covered and damaged. On the other hand, this design spoils the appearance.

For all other types of roofs, a lightning protection grid is used. It happens with different cells. Standard dimensions are 6x6 and 12x12 square meters. m. Depending on the type of roof, the angle of inclination and roofing materials, there may be other steps.

Theoretically, the grid is installed under the coating so as not to spoil the appearance. After getting lightning, the shock wave hurts several rows of tiles. For this reason, the mesh is stretched over the roofing material. For these purposes there are special devices that allow you to perform work without damaging the coating.

Lightning protection of a soft roof is carried out by the same principle. The grid must be grounded. At the same time, on the two-tie roof it is installed in such a way that the slots are separated.

Sometimes the grid is replaced with ribbon lightning. This is a simpler and cheap option. In addition, he does not spoil the exterior. But in practice, such structures do not provide appropriate protection and only slightly soften the blow.

Lightning protection device on a flat roof is a more technological process. Any elevation on a flat surface provoke the occurrence of the leader and the subsequent lightning strike. Therefore, for flat surfaces, it is necessary to install lightning tracks.

This design can be made both as a specific figure and in the form of a conventional spire. The structure is connected by a power electrical cable that provides grounding. The value is only the height of the structure. Lightning protection of the roof and the price of this service is justified, so it is better to order a professional calculation of all characteristics. The installation process can be performed independently. It is important to remember that the design should transmit a current on the power cable, so it is strictly forbidden to weld it to the roof.

Lightning protection equipment manufacturers

There are two unconditioner leaders in the electrical equipment for working with heavy duty carriers:

• Obo Bettermann,
• DEHN + SOHNE.

Both firms have proven themselves from a positive side, but at the same time offer sufficient varieties of lightning protection.

Obo Bettermann is interesting in its most powerful cables and insulation systems. The strength of the current in lightning comes up to 200,000 A, such a discharge increasing materials up to 30,000 degrees Celsius. Naturally, at such a temperature, everything is burning, which is able to burn, the rest turns into ashes. Obo Bettermann cables are designed for similar extreme situations and ensure safe grounding.

In addition, the company offers various versions of modifications, their range allows you to ground the roof as well as possible and beautifully.

Dehn + Sohne specialize in the manufacture of control equipment. Their devices are able to level even a very powerful current, redistribute the load and protect all electrical devices from breakage.

In combination, both manufacturers allow the insulation of the roof at the highest level. All the subtleties of the installation of individual devices in the smallest details are written in the instructions for them.