Direct lightning strike Vacation home It's rare, it only happens once every few years. Nevertheless, it is worth protecting yourself and even before the start of construction, consider a lightning protection system.
Is it possible to do without lightning protection?
In no case! For several reasons:
- The probability of a lightning strike into the house, although small, still exists. Especially if the building rises above all the others, is located on the top of a hill or on the shore of a reservoir;
- a direct lightning strike is not the only danger during a thunderstorm. For the electrical circuit of the house and the equipment connected to it, lightning strikes within a radius of 200-500 m are also dangerous: they cause strong electromagnetic disturbances. Able to damage equipment and lightning surges that appear due to rapid changes electromagnetic field during a thunderstorm;
- the lack of a lightning rod may cause a refusal to pay insurance compensation in case of fire.
If it is impossible to lay down conductors along the shortest path, their number is increased, and the lightning rods are interconnected. Thus, the current from the receivers is distributed in different directions.
Are there exact instructions for a lightning protection device?
Unfortunately, there are no official standards for lightning protection of private houses yet. Designers and homeowners are left to rely on common sense and experience 
electricians. The only one practical advice, which must be strictly followed: think about lightning protection as early as possible, even at the stage of designing a house and laying the foundation. Finally, it is installed at the stage of distributing electricity around the house.
How is lightning protection done?
The lightning protection system consists of several parts: a lightning rod, down conductors, grounding and special equipment that is connected to the electrical panel and protects the network from power surges. Electricians call the first three elements external lightning protection, and the device in the shield - internal.
Lightning rods of the simplest design - metal pins, the height of which depends on the height and area of \u200b\u200bthe building. So, for a house with a height of 8 m and an area of 80-100 m2, you will need a pin about 1.4 m long.
For an attic-mezzanine, a separate current collector is required, which is installed on the ridge of its roof.
Down conductors are connected to lightning rods - two for each pin. They must go to ground by the shortest path. That is why experts strongly recommend taking care of lightning protection at the design stage: when laying down conductors in an already built house, windows may meet on the way, and it will also be difficult to make case insulation of down conductors and hide them in the internal elements of the house.
grounding usually serves as a foundation, where, even at the laying stage, details for attaching current collectors should be provided. If there are no such details, separate pins are driven into the foundation and connected to each other. So that the grounding does not corrode, it is better to use galvanized metal elements.
For a house standing on a high sandy hill, an additional ground loop is needed: dry sand is a poor ground electrode.
Remember: the metal shells of all underground communications of the cottage must be connected to the ground loop!
Is there an alternative to lightning rods?
Modified and more reliable system but in comparison with lightning rods - cable. Two small pins are installed on the roof ridges, between which an uninsulated wire passes. The entire structure serves as a current collector.
On city buildings, another option is used - lightning protection network. This is a metal mesh with a cell size of 6 m, laid over the entire roof area. Wires are usually tucked away concrete screed roofs.
This technology is also suitable for small private houses, but with an amendment: it is recommended to lay the wires over the roofing material, otherwise the roof will have to be repaired after a lightning strike.
Important: the lightning protection network is used only on a non-metal roof! There should be no metal parts outside the network, including drains.
A metal roof, when properly grounded, can work as a large lightning rod. The main thing is that there should be no combustible insulation under it: at the place where lightning strikes, the metal can get very hot and even melt. By the way, for this reason, it is still better to use other options for lightning protection: repairing a damaged roof can be expensive.
During the construction of cottage settlements, external active type lightning protection can be used, which covers several buildings at once. It is based on the principle of air ionization at the lightning rod and is mounted on special masts.
An active type lightning rod is installed at a distance of 1 m from the highest point of the structure in the village, the coverage area of the active system is about 80 mg.
Today we will talk about how to protect private house from a lightning strike.
What is lightning?
Many owners of private houses try to make their home as comfortable and safe as possible, but at the same time they forget about the possibility of a lightning strike at home.
Lightning is one of the most unpleasant phenomena that can cause tremendous damage to a home.
As you know, it is a high-power electrical discharge, so even if it enters the house indirectly, it can damage electrical equipment in the premises.
It is good if there is a tall building near the house, equipped with lightning protection.
In this case, you do not have to worry about the possibility of lightning entering the house, since such houses often have lightning rods with a large protection zone, which will cover the area with adjacent buildings.
A feature of lightning is the discharge to the highest point. Therefore, if the house stands on the outskirts, it is the highest point, unless, of course, a tree grows next to it, which is taller than the house.
But the tree is also not a guarantee of protection. The danger of a home being struck by lightning increases many times over if there are reservoirs, strong streams, and swampy areas near the house.
So, if a private house is not surrounded by high-rise buildings, it is better to be safe by providing a home with lightning protection.
Striking factors of lightning
But before you figure out how to protect your home from a possible lightning strike, you should consider damaging factors this phenomenon.
There are two of these factors.
Primary.
This is a direct lightning strike into the house, as a result of which it can damage the structure, there is a possibility of a fire. This factor is the most dangerous.
Secondary.
It is less dangerous for the house and residents. This factor is reduced to the appearance of electromagnetic induction in the wiring of the house during a lightning discharge near the house.
Due to induction in the wiring, there is a significant voltage surge that can damage all electrical appliances in the house that are connected to the network.
And if you can protect yourself from the secondary factor without additional equipment by disconnecting all devices from the network during a thunderstorm, then it is impossible to protect the primary factor in this way, you need to equip the house with lightning protection.
Ohio, a house that was struck by lightning.
Since lightning is just an electrical discharge, albeit of great strength, it acts like any other discharge, that is, it moves along the path of least resistance.
Ensuring this path is the task of lightning protection.
If lightning hits a house equipped with this type of protection, then the electric discharge through it will go into the ground without causing damage to the building.
In the people, such protection is called lightning rods, lightning rods.
As for the latter, the definition is not entirely correct, because thunder is just a sound accompaniment that occurs when lightning strikes.
Criteria and types of lightning protection
Now let's analyze the types of lightning protection.
Here, this equipment has several criteria that divide it into types.
The first criterion is the method of protection.
According to it, lightning rods are divided into:
- Active;
- Passive.
Active appeared relatively recently. They have a lightning rod, which is discussed below, is equipped with a special ionizer, which “provokes” lightning with its impulses.
In fact, this device specifically attracts lightning to itself, which completely eliminates the possibility of a secondary factor of lightning strike.
Passive ones are not equipped with anything like that, lightning can discharge on it, or maybe not. This type of protection is used everywhere.
The second criterion is the types of protection.
According to it, lightning rods are also divided into two types - external and internal.
Everything is simple here - the outer one protects the house from the primary factor of lightning impact, and the inner one - from the secondary one.
And the third criterion is design features.
But here the division into types is more related to lightning rods. According to them, the lightning rod is divided into pin, cable and mesh.
Lightning protection design
Now, regarding the design of lightning protection, let's talk only about the external one.
It consists of only three elements - a lightning rod, down conductors and a ground electrode.
Lightning rod.
It takes on a lightning discharge, so it is fixed on the roof of the house so that the receiver itself is the highest point.
The simplest is the rod type of the receiver.
A metal rod with a diameter of 10-18 mm and a length of 250 mm is considered standard.
You can also use a pipe, but only its ends must be welded.
The number of receivers is calculated from the size of the building. For small houses, one is enough, if the area of \u200b\u200bthe house exceeds 200 square meters. two rods are installed with a distance between them of 10 m.
So that the discharge through the receiver does not go to the house, it is fixed on the roof with wooden bars or special fasteners.
Some not to spoil appearance at home, the lightning rod is installed on a separate support near the house.
Some, if possible, mount an additional lightning rod directly on the tree.
There is no particular difference, since even with a nearby lightning rod, the protection zone will cover the house.
The main condition for installing the receiver is that it should be located above the house, as well as other buildings near it.
Another type of lightning rod is a cable.
A cable is used, which is pulled along the entire length of the roof ridge and fixed to wooden poles. An important condition is the tension of the cable - it should not touch the roof.
The third type of receiver is a grid.
It is made from any wire (steel, aluminum, etc.) with a cross section of at least 6 mm.
It is stretched over the area of the entire roof, the cells of this grid should form a square of about 6x6 m.
At the same time, the mesh should also not touch the roof, it is fixed on wooden or special non-conductive supports at a height of 6-8 cm from the roof.
There are no strict requirements for the use of one or another type of lightning rod, any one can be used, they are all quite effective, so they are chosen at will.
Their main task is to transfer the discharge from the receiver to the ground electrode.
Most often, steel wire with a diameter of 6 mm or more is used as down conductors.
If the walls of the house are made of brick or foam block, in general, from any non-combustible material, then the down conductor can be fixed along the wall in any inconspicuous place, most importantly, not near windows and front doors.
It is possible to use a metal tape as a down conductor, but with a thickness of at least 2 mm and a width of 30 mm or more.
The down conductor is attached to the receiver using a welded, bolted or soldered connection.
The number of down conductors depends on the number of lightning rod ends.
If only one rod receiver is used, then one outlet is attached to it. When using a cable receiver, two outlets are already needed.
Also, two down conductors are used with a grid receiver.
Grounding.
The last element is the ground electrode. The simplest grounding conductor is two metal rods buried in the ground by 2-3 m.
The distance between them should be at least 3 m. These rods should be connected to each other by a jumper at a level of 0.5-0.8 m in the ground. The down conductor is connected to this jumper.
On soils with high level ground water it is better to use the horizontal position of the ground electrode at a depth of 0.8 m. metal corner or a strip with a width of 50 mm and a thickness of 4 mm.
The grounding conductor is connected to the down conductor only by a welded joint.
Features of installation of lightning protection
Based on the above, it can be understood that it is quite possible to make lightning protection yourself, having only the necessary materials.
To protect your home from lightning, you must first take measurements.
It is necessary to find out the height at which the receiver should be located, as well as determine the method of its attachment.
Then you need to calculate the length of the down conductor. Here it is important to take into account that the path of the lightning charge to the ground electrode must be as short as possible. Therefore, you should not make any contours, bends, etc. And even more so, it is impossible to form rings from the branch.
As for the ground electrode, it should be located at least 1 m from the nearest wall of the house. After all the calculations, you can proceed with the installation.
You need to start with the ground electrode.
If it is made of rods, it is enough to dig a trench 0.5 m deep and 3 m long.
At the edges of this trench, drive rods at least 2 m long into the ground.
Then, using a welding machine, weld a jumper to these rods.
If the ground electrode is horizontal, then you will have to dig a trench much deeper.
An important condition must be observed here - it should not come into contact with the roof of the house, therefore, to fix it, use only wooden supports.
In this article you will learn:
- Why thunderstorms and lightning strikes are dangerous for private households
- What are the types of lightning protection in a private house
- What is included in the standard composition of the lightning protection system
- Passive or active lightning protection? Advantages and disadvantages
- Fundamentals of the device for external protection of a private house
- What are the categories of structures according to the degree of lightning protection
- Materials used and corrosion issues
- What is the smallest allowable distance (separation gap)
- What should be a lightning rod
- How to choose a down conductor? Types of down conductors.
- How to fix lightning protection elements correctly? Roof and façade holders, downpipe holders, terminals and connectors, earthing fixing elements
- How to choose grounding
- How to properly connect the grounding system to the down conductor of the lightning protection system
- Features of the device of the system of moniezashchita for different types and roof configurations
Atmospheric electricity has a huge potential, thousands of times greater than the power of man-made installations. A potential difference of up to 10 million kilovolts can be created in a thundercloud, the discharge current reaches 200,000 amperes, it is not possible to protect oneself from such a force that causes large-scale destruction without special protective systems.
Danger of lightning for private houses
The saturation of homes with electronics, household appliances and means of receiving terrestrial transmission channels has dramatically increased the likelihood of lightning exposure, which is explained by the physical characteristics of electrostatic forces. Lightning discharge, falling into an unprotected structure, not only damages electrical networks and devices, but the likelihood of fires is even more terrible, which is caused by lightning in every fifth case. Protection against lightning strikes of private houses is entirely in the hands of the owners, which cannot be the reason for abandoning the lightning protection device, given the terrible consequences that overtake unprotected houses.
Types of lightning protection
At present, two types of protection against the effects of lightning discharges have been developed and applied in detail: these are external and internal protection.
External lightning protection
It is a well-known lightning rod in the form of a metal rod, towering above the roof of the house. Such protection consists of three main elements.
1. Lightning rod - a metal rod, which can be steel, copper or aluminum.
2. Down conductor, which is used as a metal conductor connecting the lightning rod with grounding.
3. Grounding, consisting of steel ground electrodes buried in the ground, connected into a single circuit using metal tires.
In fact, for all three elements, a conductor of different sections is used, the minimum values \u200b\u200bof which are selected in accordance with the material used according to the following table:
Depending on the type of roof and roof configuration, in addition to the rod receiver, a steel cable stretched over the protected object or a special mesh can be used (see the figures below), or even a combination of these elements can be used.
Increasingly, external protection systems are used, using an active method of searching for and removing lightning discharges on early stages their development (more on this below).
Internal lightning protection
The currents resulting from the manifestation of lightning flow through resistor and inductive connections, causing overvoltages that can melt microcircuits and disable electrical equipment. To protect against such consequences, SPDs are used - devices for protecting internal networks from surges. The magnitude of the impulse overvoltage depends on the location of the lightning strike, and therefore, overvoltages of type I (induced from a direct lightning strike) and type II (from an indirect strike) are distinguished. Overvoltages of type I are especially dangerous, since they are 10–20 times higher than the magnitude of overvoltages of type II.
Standard composition of the lightning protection system
To protect a private house from the damaging effects of lightning, a standard set of tools is used:
- External protection with lightning rods, down conductors and grounding;
- Protection against drift of high potentials by equalization of potentials;
- Overvoltage protection (internal overloads) by means of arresters or SPDs.
From the above list, the methods of external protection have the greatest differences, which can be active and passive, and with passive protection they have significant differences depending on the configuration of the roof and the type of roofing.
Active lightning protection
IN last years active lightning protection is gaining popularity. Its spire has a special head - an ionizer, which generates a counter flow of electrons. As a result, lightning is attracted, after which the resulting discharge is discharged through the down conductor to the ground, where it is extinguished. Active protection is distinguished by a large radius of the protected zone, which is 8 times greater than the protection radius of a passive lightning rod of the same height.
Active protection characteristics provide a significant reduction Supplies for roofs with a complex configuration, as well as time for equipment installation. The appearance of a mast with an ionizer looks aesthetically pleasing, there is no need for grounding of individual metal structures located under the protective zone cap.
Among the shortcomings of the active method, one can note the short period of its application, which makes it impossible to talk about many years of positive experience. Moreover, more and more cases of lightning strikes into objects with active lightning rods have been recorded lately, and manufacturing companies are being sued in connection with this.
Device for external protection of a private house against lightning
When installing lightning protection for private houses, the principles and designs of protection set forth in the special literature (“Instruction for the installation of lightning protection ...” SO 153-34.21.122-2003 and RD 34.21.122-87) should be used.
The severity of the destructive effect of lightning depends on the presence of gases, dust, vapors, or their mixtures on the affected object that can explode when an electric spark hits. Important factors Classifications of buildings by classes (or categories of lightning protection) are: the expected estimated number of lightning strikes into the object, its value, the threat to human life and the surrounding environment. Therefore, private houses, cottages and garden houses It is customary to refer to the III group of buildings in which there are no such hazards.
Depending on the degree of reliability, 4 classes of lightning protection are accepted:
- the first - the reliability of more than 99% (for example, ammunition depots, gas stations, refineries);
- the second - from 95 to 99% (large enterprises that pose a threat to the environment);
- the third - from 90 to 95% (commercial, office and residential buildings);
- the fourth - at least 85% (buildings in which there is no electrical wiring and the constant presence of people).
Corrosion problems
Metal elements of external protection are constantly exposed to weather conditions, which cause corrosion. Slow down metal degradation and ensure long service life structural elements You can protect yourself using the following methods:
- The use of metals that are not easily corroded, these are stainless steels, copper or aluminum;
- The use of protective electroplated coatings, the most common of which is galvanizing;
- For bolted joints - metal cleaning at the point of contact, tight fitting and the use of conservative lubricants;
- The choice of an overestimated section of metal structures relative to the design indicators, which affects the cost of the system.
You can read more about the components and materials for lightning protection and grounding of houses, the features of their use in our large review material on this page.
The rate of corrosion development is affected by the incompatibility of certain metals. So, copper is in very poor contact with galvanized steel and aluminum, so such contacts should be avoided. To connect incompatible materials, special clamps are used, in which the ends are made of different metals.
Smallest allowable distance
Currents induced in metal conductors by lightning discharges can cause a spark discharge. The distance between down conductors and metal elements must be such as to prevent sparking, this is the smallest allowable distance, denoted by the letter S.
In addition, there are also requirements for observing the distance between the fasteners of the lightning protection system, the location of down conductors relative to window openings, doors and other building structures. You can learn more about the information in the material on how to properly lay down conductors.
If metal constructions fences, facade elements, pipes are located closer than 1.0 meters from the down conductors and do not have a conductive connection with the structures of the protected building, such elements must be connected directly to the lightning protection system.
Requirements for lightning rods
Stage 4. We draw conclusions from lightning receivers to future down conductors. Important clarification! To increase the efficiency of the system, the ends of the conductor on the skates must be planned 15 cm longer and bent slightly upwards.
An example of a lightning protection device for a private house for a flat roof
For flat roof we use the "lightning protection mesh method".
Stage 1. First of all, in those areas where the probability of a lightning strike is the highest, and this is the edge or ledges of the roof, we plan a conductor that will act as a lightning rod or the basic contour of a lightning protection mesh.
Stage 2. Similarly to the previous example, we find the protection angle, transfer it to the drawing and check whether all the elements of the structure are covered by the protection zone.
Stage 3. Actually, we supplement our contour with grid cells based on the fact that for buildings of the III class of lightning protection, this size should be no more than 15x15 meters, that is, if the perimeter of your house is not larger, then it will be enough to leave only the basic contour, otherwise we advise you to divide the entire space into equal cells and lay conductors in this way.
Stage 4. If the roof has additional protruding elements, then we supplement the lightning protection device with lightning rods for the corresponding elements according to standard rules.
Basic lightning protection schemes for standard projects
The figure below shows the lightning protection options for several standard projects houses (click to enlarge).
It is worth noting that in three variants the guide on the skate is raised to a certain height. This suggests that the angle of the roof is greater than the angle of protection, and some part of the building does not fall into the protection zone. In fact, this is the simplest version of a wire lightning rod.
The shown grounding schemes should not be considered as focal, they are depicted only conditionally (for more details, see above).
What is lightning, we know from school desk. An electric discharge with a power of 100-200 thousand amperes destroys all objects where it hits. And most likely, tall buildings and trees attract lightning.
Lightning protection of a private house is relevant today more than ever. Our homes are literally crammed with electronics, household appliances, mobile phones which increases the risk of lightning exposure. Danger of lightning for private houses, not equipped with lightning rods is large - fire, destruction in the event of a direct hit by a discharge. The consequences of a discharge in the immediate vicinity of the building may be the failure of the power grid or a separate device - a TV, computer, etc.
- Internal, protecting against a discharge that did not fall directly into the house, but, for example, into a power line that feeds the internal wiring. In this case, an overvoltage occurs in the electrical network, the consequences of which can be deplorable. The internal protection is not visible, it is a small device - a limiter, a surge arrester, an SPD installed in the switchboard.
- External protection is a familiar lightning rod (as lightning protection is often incorrectly called) installed on the roof.
External protection of a private house from lightning
The system is either passive or active. The principle of operation of the first is simple, like everything ingenious. A metal lightning rod on the roof catches (attracts, intercepts) a lightning discharge and directs it through a current lead to the ground, to the grounding conductor.
Active lightning protection
Such lightning protection is more effective, it operates within a radius of 100 meters from the "cunning" lightning rod, which, by ionizing the surrounding air, intercepts the lightning discharge. Then it works like passive protection. The main advantage of the device is the "coverage" of lightning protection of neighboring residential buildings and outbuildings on a fairly large area.
Types of external lightning protection at home
According to the type of construction, modular-pin, cable and mesh lightning protection are distinguished.
pin
The pin system is called because of the lightning rod, which is installed in the highest part of the roof, and is a metal rod (pin). This design is suitable for lightning protection of a private house with a roof made of metal or any other material.
Rope
The installation of this type of protective device is allowed if the roof is slate, tiled, but not metal.
The lightning rod is a cable (thick wire, wire rod) stretched at a height of 0.3-0.5 m along the ridge of the house.
Mesh
The system is considered the most difficult in terms of installation. It is made from wire rod with a diameter of 6-8 mm, which, in the form of a grid with cells of 6x6 meters, is laid over the entire roof area. At the intersection of horizontal and vertical rods - welded. It is attached to the roof with brackets.
Mesh lightning protection of the house is installed, like cable, on a slate or tiled roof.
Down conductor
For this element of the system, round steel (copper, aluminum) with a diameter of at least 6 mm is used. The down conductor is fastened with brackets along the roof and walls. Usually, during installation, they try to lay the “route” away from window and door openings, as required regulations, and not to spoil the exterior of the building.
When laying the conductor, you need to follow some simple rules:
- On the wooden surfaces the conductor must be fixed at a distance of 15-20 cm from the wall;
- If a cable receiver of great length, a large mesh or pin consists of several elements, then there should be several down conductors (SO 153-34.21. 122-2003)
During the construction of a new building, the lightning protection of a cottage or house is already "laid" in the project documentation. But if a country house or country house just bought and there is no “lightning rod” on it, then the most reasonable solution would be to protect yourself and your loved ones from lightning discharges on your own, or with the help of hired specialists.
If you have the skills to perform construction work, do-it-yourself lightning protection of a private house will not be a problematic issue, but it will save money.
Ground loop
The principle of the grounding device is extremely simple. Three steel pin-modules 1.5-2 meters long, 16-20 mm in diameter, zinc-coated, are driven into the ground and connected in series.
This design has a number of advantages:
- Possibility of installation at any depth without the use of special equipment;
- Small labor intensity. The work can be done by one person;
- Large immersion depth of the pin-electrode increases the efficiency of grounding;
- Connection of elements does not require welding (on special clamps);
- The whole system is hidden underground.
The contour is driven into the ground no closer than 1 m to the foundation of the house, and no closer than 5 m to the front door.
The principle of operation of the internal protection of the house against lightning
It is difficult to imagine life today without electronic and household electrical devices and appliances. All this equipment is connected to the mains, and cables from the computer and TV also go to the local network and satellite dish.
Data transmission lines through receivers, servers, distribution devices, power lines, are subject to lightning strikes, electromagnetic fields. Under certain circumstances high voltage and a large current through the cables move to a low potential, i.e. TV, refrigerator, computer. The result may be the failure of electrical appliances, fire, a threat to human life.
To protect yourself and your home, you need an internal lightning protection device for a private house or surge protection.
Such protection operates simply - it instantly equalizes the potentials between the conductors of the electric current. This task is performed by the SPD - special device surge protection.
Installation of this device is possible only after a reliable external protection device. To implement the lightning protection system of a private house, a project is being developed, which takes into account all the ways to enter the high voltage building.
After the installation of the SPD, non-current-carrying elements are connected to the ground bus, and lines that cannot be grounded are connected to the bus through the SPD.
For the selection of an SPD, there are rules that can be divided into groups depending on:
- Protected network indicators - current, voltage, frequency, wire section;
- Type of network - power supply, cable TV, phone line, alarm, etc.;
- Significance of the protected object - PC, TV set or banking server.
Do you need lightning protection for a private house?
You can definitely answer - you need it! There is still a lot of unknown in the world, especially the mysteries of nature. If in a city a television tower or a high-rise building “protects” a lot of surrounding houses from lightning, then in a privately built area, as a rule, there are no such structures. But not far from the house there is a tall pine tree, which serves as a natural "lightning rod". But this is a theory, it’s still better and calmer to feel safe in “your own fortress”.
Lightning is one of the most terrible enemies for a private house. Its destructive power is so great that you can lose your shelter in a matter of seconds. Of course, the case of a lightning strike in a house is not the most common cause of property loss. Many are just lucky to have a home near lightning rods, power lines or high towers. However, as long as there is a danger of sudden and complete destruction of all property, it is hardly possible to live in peace.
The probability of lightning hitting a house increases many times if it is located on a hill or near water bodies. In such cases, the implementation of a lightning protection circuit at construction work necessarily. According to SNiP, all private buildings are classified as buildings with a third fire safety class, which means that they are subject to lightning protection without fail. As a rule, lightning protection is designed together with the house and installed during its construction.
How much lightning protection is needed for a private house
To properly build lightning protection, you need to know the nature of the occurrence of lightning. Due to the accumulation of a large electric charge in rain clouds, a huge impulse occurs, in other words, a discharge electric current at the highest point in the area.
The current strength of an electric discharge during a lightning strike reaches 100 thousand amperes, and in some cases up to 200 thousand amperes. About 200 lightning strikes occur every second on the planet. Even if we consider that the probability of it getting into a particular house is not so great, it is still better to secure your home in advance and install a structure that protects the house from a lightning strike.
During the passage of an electrical discharge colossal thermal energy is released through the materials of the house, which causes fires and destruction. As you know, most of the suburban buildings are built from wooden materials, namely they are most at risk of rapid ignition.
Based on this, lightning protection of a house becomes an important and mandatory task during its construction. Moreover, regardless of the location of the residential building in the city or outside it and the types building materials used for its construction, lightning protection must be.
Principles of operation and types of lightning protection
Lightning protection for a private house can be of two types:
- Active.
- Passive.
Traditionally, the first type of protection is used - passive, which consists of a lightning rod, a current outlet and grounding. The principle of operation of such protection is very simple.. Lightning, striking the receiver, passes through the lightning rod, which directs the discharge to the ground. When designing any lightning protection system, it is necessary to take into account the characteristics of the material from which the roof is made, the roof structure and its features.
Active lightning protection works on a slightly different principle. The discharge of electric current is intercepted by a lightning rod, which creates an ionized field around itself, attracting lightning. Further, the principle of operation is identical to passive protection. At the same time, its active type acts within a radius of up to one hundred meters, while the passive one protects only the house itself.
Active lightning protection is the most preferable and it is installed in many countries to protect the house and the entire surrounding area. However, it has a high cost, which may not always be appropriate to install it.
Do-it-yourself lightning protection of a private house
You can ensure the safety of a residential building with the help of lightning protection made by yourself. The lightning rod circuit is quite simple, it's easy to do it yourself. Any such security system of a private house is based on the manufacture of a lightning rod from available building materials.
Any lightning rod has three main components, as shown in the diagram:
- Lightning rod.
- Down conductor.
- Ground loop.
Lightning rods
A conductor made of metal, the task of which is to take over the electric discharge of lightning, is called a lightning rod. It is installed actually high place roofs, while on the roof having complex structure, install several such lightning rods.
By their own design features lightning rods can be of several types:
- metal pin;
- metal cable;
- metal grid.
metal pin
With this method of lightning protection at home, a metal pin is made, from 20 centimeters to one and a half meters long. It should be mounted on the high point roofs of a private house.
The material used is copper or galvanized steel due to its high resistance to oxidation. Such a pin can be of any shape. The cross-sectional area should not be less than 100 m2. If the pin has a round shape, then its diameter must be at least 12 millimeters. The use of a hollow pipe is allowed, but in this case its diameter should be slightly larger, and the end facing upwards must be welded. How to protect your home from lightning suitable for any type of metal roofing, including metal tiles.
metal cable
A device with a metal cable is also quite simple to do with your own hands. The whole structure consists of a cable and a pair of supports that can be made of metal. However, in this case, they will have to be isolated.
A steel cable with a diameter of at least 12 mm is pulled along the roof ridge and fixed at the edges. The cable should be at a height of 1-2 meters from the roof ridge.
Metal grid
Lightning rod with receiver wire mesh is the most the best option tile roof protection.
When installing the grid, it is fixed along the roof ridge with branches from down conductors that have reliable grounding over the entire roof area.
All lightning rods on the roof must be connected to ladders, gutters and any other metal objects.
When large and tall trees grow next to a private house in the immediate vicinity, one of them can be used as a lightning rod. To do this, the metal pin should be installed so that it is one and a half meters higher than the crown of the tree, and then connected to the down conductor. An important condition is the height of the tree- it should be 10–20 cm higher than the house.
Creation of a down conductor
Down conductor - one of the components of the lightning rod, responsible for the electric discharge wire from the lightning rod to the ground loop. It is made of steel wire with a diameter of at least 6 mm. One of its ends is welded to the base of the lightning rod, and the other to the ground loop. The quality of welding should be given special attention, in order to avoid breakage at the attachment point. The current that passes through the down conductor can reach 200,000 amperes.
It is necessary to fix the down conductor along the contour of the roof and the house with the help of insulators at a distance of 2–3 cm from the roof and walls . If there are several down conductors, then the distance between them should be at least 25 meters.
Do not fasten the wire near the doors and doorways. When installing, avoid sharp bends and places where it can be damaged by snow or debris. The down conductor should be as short as possible, and it should be located in places where there is the greatest risk of lightning strikes: on sharp ledges, gable edges, etc.
Grounding the lightning rod
The ground loop completes any design of a lightning protection device. Its task is to ensure reliable contact of the entire device with the ground. Externally, the design looks like three large electrodes that are interconnected and recessed into the ground.
To assemble the device responsible for grounding, you will need steel with a cross section of 80 m2 or copper with a cross section of 50 m2. In a trench dug in advance, about one meter deep and 3 meters wide, two metal rods made of copper or steel should be driven in along the edges. Then they are interconnected by welding and a down conductor from the house is welded to them. The entire structure is driven to the ground into the ground.
When assembling the grounding device, remember that it must be located no closer than five meters from doors or windows, walkways, porches and paths. Distance from the walls of the house must be at least one meter.
Lightning protection care
Every year before the start of the thunderstorm season, special attention should be paid to the preventive inspection of lightning protection at home. All components of the lightning rod and attachment points must be inspected, if necessary, painted or repaired.
Every three years, a major inspection of the entire system should be carried out. Check the connection points of the down conductor and the ground loop, clean and tighten the contacts there. Faulty clamps - replace.
Every five years, the ground loop electrodes are inspected. To do this, they must be removed from the ground and carefully checked for corrosion. If, for its reason, the cross section of the electrodes has decreased by more than a third, then they should be replaced.
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