Residents of cities do not care much about lightning protection and grounding, the state has already taken care of them, obliging designers and builders to provide appropriate technical solutions. The issue of protection against lightning is especially relevant for owners of cottages and country houses.

To do lightning protection or not to do it - the homeowner decides for himself. However, the construction of grounding and a reliable lightning rod reduces the risk of fire at times, allows you to protect wiring, electrical appliances and the lives of the inhabitants of the house.

Lightning Hazard

Clouds are water vapor or small ice crystals. They are constantly moving, rubbing against warm air streams and becoming electrified. When the charge difference between them reaches a critical value, a discharge occurs. This is lightning.

When the conductivity between the cloud and the ground is the lowest, then the lightning strikes the ground, all the accumulated charge flows into it. Then you need grounding to take over the energy of the discharge.

Lightning strikes the highest point of a structure minimum distance from the cloud to the object. In fact, it turns out a short circuit, gigantic currents flow, huge energy is released.

If there is no lightning protection, then all the lightning energy is perceived by the building and spreads over conductive structures. The consequences of such an impact are fires, injuries to people, failure of electrical equipment.

Lightning protection takes on the energy of the discharge and forwards it through the current conductor through the grounding conductor to the ground, which completely absorbs it. Therefore, lightning rods (lightning rods) and other elements of lightning protection are made of conductive materials with high conductivity.

Protection types

According to the location, lightning protection is divided into external and internal. External protection according to the principle of operation is divided into passive and active. A passive type lightning protection device includes three mandatory parts:

• lightning rod;
• down conductor (current conductor);
• ground electrode.

Depending on the structure of the roof, various lightning rods are installed. In active lightning protection at the top of the rod or mast there is an air ionizer that creates an additional charge and thus attracts lightning. The radius of action of such protection is much larger than the passive one; one mast is enough to protect the house and the site.

Internal lightning protection

Lightning protection is especially needed inside buildings with big amount computer equipment. Internal lightning protection is a complex of surge protection devices (SPD).

When a lightning discharge hits the power line, huge short-term overvoltages occur in it. To extinguish them in parallel with the conductors phase and zero, phase and earth, zero and earth, SPDs are installed. These are very fast devices with a response time of 100 ns to 5 ns.

The installation scheme and characteristics of the SPD depend on whether there is external lightning protection or not. They differ in design, they are air or gas dischargers, varistors, but the essence is the same.

In the event of a short-term overvoltage, the protected circuit is shunted and all the discharge energy is taken over. But there are devices serial connection. The principle of operation is the same, when overvoltages occur, the entire voltage drop occurs on the device.

SPDs are divided into three classes. First class devices are installed in the main switchboard. The SPD reduces the voltage to 4 kV. Devices of the second class are installed in front of the introductory machine of an apartment or house electrical panel and reduce the voltage to 2.5 kV.

Third class devices are installed in close proximity to protected devices (computers, servers and similar devices). They provide a reduction of up to 1.5 kV. This voltage reduction is sufficient for most equipment, especially if the duration of the overvoltage is short. it is recommended to entrust to specialists.

Natural lightning rods

In addition, there are natural lightning rods. Our ancestors wittingly or unwittingly also had good lightning protection. The tradition of planting a birch near the house has saved more than one life and more than one house. Birch, despite the fact that it does not conduct electricity very well, is an excellent lightning rod and at the same time provides grounding.

And all because of the powerful root system, which spreads almost on the surface of the soil. Due to this, the energy of lightning, when it hits a tree, spreads over a large area and safely goes into the ground. Pine and spruce are even better as lightning protection, but they cannot be compared with birch due to the fragility of the wood.

Design of lightning rods

In the general case, lightning protection of buildings and structures is a complex of a lightning rod, a conductor and a ground electrode. Lightning rods are used in the form of a rod, a network and a stretched cable.

Rod lightning rod

The design of the rod system is simple. The lightning protection pin is connected by means of a down conductor to metal pins in the ground, which provide grounding.

Rods (pins) are made of galvanized or copper-plated steel with a height of from half a meter to 5-7 meters. The diameter depends on the height of the rod and the climatic region of the location. Copper-plated rod has better electrical conductivity compared to galvanized steel.

Depending on the configuration of the building and its roof, several rods are installed on the roof. They are attached to the ridge, gable, ventilation wells and other capital structures.

The zone of influence of lightning protection is a cone with a vertex at the tip of the lightning rod. The rods are arranged in such a way that their areas of action cover the entire building. For rod lightning rods, the rule of a protective cone with a 90 degree top is valid for a rod up to 15 m high. The higher the lightning rod, the smaller the angle of the top of the protective cone.

Network lightning rod

The lightning protection network is a galvanized or copper-plated wire with a diameter of 8-10 mm, covering the entire roof of the building in the form of a network. Usually, lightning protection in the form of a grid is installed on flat roofs.

The network is formed by wires perpendicular to each other with a certain pitch. With the help of holders, the wires are interconnected and attached to the roof. Sometimes, instead of a wire, a steel strip is used.

The wire or strip must be connected to ground. Welding is used for the connection, but it can be done with special clamps. Clamps for connecting ground electrodes to conductors are often included if you purchase all the parts in a specialized store.

Rope lightning rod

Rope lightning rods are a steel or aluminum cable stretched between two masts. The masts are connected to down conductors, which, in turn, are connected to grounding. Imagine that the cable is the ridge of a gable roof.

Then the area under this virtual roof will be protected from lightning strikes. Thus, by stretching several cables over the roof of the house and the adjacent territory, it is possible to provide reliable lightning protection.

Conductors are galvanized or copper-plated steel wires with a diameter of 10 mm, steel strips with a cross section of 40x4 mm are often used, coated with zinc or copper. They connect the lightning rods to the ground electrode.

The lightning protection kit also includes holders of lightning rods and conductors. They are made of steel and plastic materials, have a variety of designs.

Location of ground electrodes

Grounding lightning rods, in the simplest case, is three three-meter metal rods driven into the ground at a distance of 5 meters from each other. Between themselves, the grounding pins are connected by a steel strip located at a depth of 50-70 cm underground.

The connection is made by welding, which are then covered with an anti-corrosion coating. At the locations of the pins, the rods must come to the surface in order to be able to connect the conductors.

Grounding should be located at a distance of at least 1 meter from the structure and more than 5 meters from the porch, paths and other places where people constantly walk. This is necessary so that a person does not fall under the step voltage, which is formed when the lightning charge spreads from the grounding conductor over the ground.

If the building has a massive reinforced concrete foundation, then lightning protection grounding is recommended to be located away from it and mounted internal lightning protection in the form of lightning arresters to protect equipment. This is necessary because of the transfer of part of the charge to the foundation and all elements that have good contact with it, primarily equipment cases, engineering communications.

Resistance Requirements

The ground loop of the house must be connected to the lightning protection ground through steel conductors that are welded together. The grounding resistance should be as low as possible. The standard value is 10 ohms for soils with resistivity up to 500 ohms, but for large values, a different resistance is allowed, which is calculated by the formula:

Rz is the resistance of the ground electrode, and ρ is the resistivity of the soil.

To achieve the standard value, the soil is sometimes replaced. A trench is dug, a new soil with the appropriate characteristics is laid, and after that, grounding is mounted. Another option is to add chemicals.

After installing lightning protection grounding, it is necessary to regularly measure its resistance. If it goes beyond the standard value, then you will have to add a pin or replace it with a new one.

In this case, close attention must be paid to the connections between the elements of the device. The use of stainless materials will significantly increase the service life of the earth electrode.

IN Everyday life Every person has long been accustomed to using electrical appliances. It is quite difficult to imagine life without electrical engineering. In order not to face a threat in the event of a malfunction of the equipment high voltage for health and life, it is required to install a lightning protection and grounding loop.

Grounding is carried out with special equipment that connects the elements of devices that are not intended to be energized to the ground.

In cases where the insulation of electrical appliances is broken, the current flows to elements that are not intended for it, including the body of the equipment.

Insulation breakdown can result in equipment failure, and if a person touches parts, you can get harm to health or death.

The ground loop allows most of the current to go to ground. To do this, it is necessary to observe the minimum resistance indicators.

Device

The grounding device diagram includes metal pipes, rods that are interconnected by a metal wire with a deepening in the ground. The device is connected to the shield using a bus. The grounding structure should be located at a distance of no more than 10 m from the house.

To make a ground loop with your own hands, you can use any metal forms as electrodes that can be hammered into the ground and have a cross section of more than 15 sq. mm.

Metal rods are placed in a closed chain, the shape of which depends on the number of electrodes in the circuit. The structure should be deepened into the ground below the freezing level.

You can create a contour with your own hands from improvised materials, or purchase a ready-made device. Ready-made ground loop equipment is distinguished by high prices, but at the same time it is convenient to install and will last a long time.

Circuits are divided into two types:

1. traditional;
2. deep.

The traditional circuit is characterized by the location of one electrode from a steel strip in horizontally, and the rest are installed vertically, pipes or rods are used for them. They deepen the contour in that part that is less accessible to people, most often they choose the darkened side, in order to maintain a single environment.

The disadvantages of the traditional circuit system include:

• complex execution of works;
• grounding materials are prone to rust;
• the environment of occurrence can create unacceptable conditions for the circuit.

The deep contour is devoid of most of the disadvantages of the traditional one; special equipment is used for it.

Has a number of advantages:

• equipment meets all established standards;
• long service life;
• the environment does not affect the protective functions of the circuit;
• ease of installation.

Loop installation requires a mandatory check of the entire grounding system. It is necessary to verify the quality of the work performed, to verify the strength of the circuit, if there are any unconnected parts.

It is obligatory to conduct research from licensed specialists. For the installed ground loop, a passport, an inspection protocol and an act of admitting equipment to work are issued. The ground loop must comply with the standards set out in the PUE.

Grounding for transformer

For grounding the transformer booth, an external or internal circuit is used, the choice of option depends on the design features.

The outer contour is created for a substation consisting of one chamber.

The scheme of the equipment consists of vertical rods and a horizontal steel strip. The dimensions of the horizontal earth electrode are 4x40 mm.

The resistance index for the circuit should be no more than 40, for the earth it should not exceed 1000. Based on the indicated parameters, the circuit should consist of 8 electrodes with dimensions of 5 m and a cross section of 1.6 cm. The circuit should run no closer, than a meter from the walls of the building where the substation is located. The depth of the ground loop is 70 cm.

To create lightning protection for the transformer, the roof is connected to the ground loop using an eight-millimeter wire.

If the substation consists of three chambers, then along the entire perimeter constituent parts a strip is set from the contour. This measure allows you to secure all elements of the metal structure.

To do this, the ground bus is fixed with the help of holders at a distance of more than half a meter between them. The distance from the surface should be 40 cm. The contour elements are welded or bolted. For a solid connection, a wire without insulation is used. Grounding conductors are laid through the wall and painted in green color, on which yellow stripes are made at a distance of 15 cm.

Grounding for a three-phase network

If the house uses a network with a voltage of 220 V, then grounding is not necessary, you can limit yourself to grounding the equipment.

A ground loop for houses with a 380 V network is required.

The difference between the two loop systems lies in the resistance values ​​for the network. In the case of 220 V, the resistance should be no more than 30 ohms; for a three-phase network, the indicator varies from 4 to 10 ohms. This is related to the level of earth resistivity. The soil in different areas has different composition, and therefore each soil has its own resistance indicators.

Before performing work, an accurate calculation should be carried out for the circuit in order to calculate the number of required grounding conductors for the network.

The calculation is made according to the formula R=R1/KxN, where R1 is the resistance of the electrode, K is the coefficient characterizing the load on the network, N is the number of electrodes in the circuit.

To create a circuit for a three-phase network, special attention must be paid to materials, because. this network is demanding on the quality of grounding.

The choice should be based on the following requirements:

• if the function of the electrode is performed by a pipe, then its wall should be no thinner than 3.5 mm;
• when choosing a corner, pay attention to the thickness, which should be at least 4 mm;
• cross-sectional diameter of the pins is not less than 16 mm;
• the connecting strip between the grounding conductors must meet the dimensions of 25x4 mm.

The installation of the circuit is carried out along the perimeter, its shape can be any, depending on the number of electrodes. Most often performed in the form of a triangle. Grounding equipment is screwed into the ground to a depth of half a meter.

The distance between the corners, which is equal to the length of one earth electrode. The connection to the strip is made with bolts or by welding.

At the end of the installation work, the office, a bus is attached to it and connected to switchboard. An example of a ground loop is shown in the photo.

The creation of systems for protecting electrical appliances from the effects of unwanted voltage and natural phenomena such as lightning is important point. The measures taken make it possible to protect a person from the harmful effects of current, as well as to avoid damage to equipment.

The creation of ground loops and lightning protection is possible with your own hands. It is important that the ground loop meets the requirements of the PUE and accepted standards. The quality of materials and workmanship is reflected in the level of protection of electrical appliances. Incorrect execution can cause more voltage to be output, which will cause harm.

The lightning protection circuit is a complex system for protecting an object from direct lightning strikes: lightning rod, down conductor, grounding. The classical scheme proposed by Benjamin Franklin back in 1752 underlies all modern systems lightning protection. Proven technology, combined with the latest equipment, professional design and installation, provides almost one hundred percent protection against lightning strikes!

Lightning protection contour of buildings and structures

Lightning rods

• Rod lightning rod. Metal rods are installed on the roof or at the highest points. To increase the height of the structure, special metal masts are used. For large objects, it is recommended to arrange several separate rods along the perimeter with autonomous down conductors.
• Rope lightning rod. Lightning strikes a cable stretched between supports. The technology is appropriate for extended objects. A typical example is power lines, which are protected by lightning rods.
• Lightning mesh. The system is mainly used for flat roofs: a metal mesh is arranged over the entire area in increments of up to 5x5 m. It should be noted that the mesh does not protect protruding objects, such as antennas or chimneys. That is why rods are also included in the lightning protection scheme, including them in a common circuit.

In addition to classical solutions, active lightning rods are used. Devices ionize the air, provoke a lightning strike. Due to this, it is possible to reduce the number of lightning rods and the overall height of the lightning protection circuit.

Down conductors

Aluminum or steel conductor, the main task of which is to transfer current from the lightning rod to the ground electrode. As a rule, external down conductors are installed on buildings, but in some cases, according to the RD instructions, it is allowed to use building structures, for example, reinforcement in reinforced concrete blocks. However, this is unacceptable in the presence of highly sensitive electronics: the electromagnetic field created during the passage of the discharge can damage the equipment.

For the down conductor, a conductor with a cross section of 6 mm is used, all connections are welded. In places where contact with a person is possible, the cable must be isolated. In addition, there must be direct access to the down conductor for regular inspections.

grounding

So, the lightning rod received the discharge and transmitted it through the down conductor to the ground electrode or ground loop - several vertical electrodes installed in the ground and connected to each other by a horizontal conductor. The sole purpose of a grounding device is to dissipate the resulting current into the ground. To save space, the contour is usually formed along the perimeter of the object, but not closer than 1 m to the foundation. The RD instruction requires at least 3 electrodes in the circuit, however, modern technologies offer the most effective solution: installation of a composite depth electrode. Due to the immersion to a depth of up to 30 meters, to achieve the required resistance threshold, it is enough to install one earth electrode.

Calculation of the lightning protection circuit

Correctly calculating and designing lightning protection is a key task to ensure the safety of a building from direct lightning strikes. For complex objects, as well as systems exceeding 150 m in height, the calculation is performed using special computer programs. For all other buildings and structures, instructions SO 153-34.21.122-2003 provide standard formulas for calculations.

The protection zone for a circuit with rod lightning rods is a cone in which the highest point coincides with the top of the lightning rod. The protected object must completely fit into the protective cone. Thus, the protection zone can be increased by raising the lightning rod or installing additional rods.

According to a similar principle, the contour of the cable lightning protection is also calculated. In this case, a protective trapezoid is obtained, the height of which is the distance between the cable and the ground.

Ground loop resistance

Grounding resistance is measured in ohms, and ideally should be 0. However, in practice, the value is unattainable, so the maximum threshold for lightning protection is set to no more than 10 ohms. However, the value depends on the resistivity of the soil, therefore, for sandy soils, where this parameter reaches 500 Ohm / m, the resistance increases to 40 Ohm.

Combining the ground loop and lightning protection

In accordance with paragraph 1.7.55 of the Electrical Installation Code for equipment and lightning protection of buildings of category II and III, in most cases, a common ground loop is arranged. However, it is necessary to distinguish between types of grounding:

• Protective - for the electrical safety of equipment.
• Functional - necessary condition for the correct operation of the equipment.

It is forbidden to combine functional grounding with a protective or grounding conductor of a lightning rod: there is a risk of high potentials entering and failure of sensitive equipment.

In this case, it is possible to combine grounding for a lightning rod and protection of electrical equipment or arrange it separately, but connect it to each other through a special clamp for equalizing potentials.

Designing lightning protection is a responsible and complex task. Entrust the protection of your home or office to professionals, contact the experienced specialists of our company! You can get advice on the website or by phone.

grounding- these are the connections of a part of the electrical network or equipment with a grounding device. The grounding device is a ground electrode - a conductive part that is in contact with the ground. The grounding conductor can be in the form of metal elements of complex shape.

The quality of grounding is determined by the value of the resistance of the grounding device, which can be reduced by increasing the area of ​​the ground electrodes or the conductivity of the medium. The electrical resistance of the grounding device is provided for in the project in accordance with the requirements of the Electrical Installation Rules.

Such a ground loop is installed in a building-free zone of the site. Grounding is subject to:

• household electrical devices unit power over 1.3 kW;
• metal cases of bathtubs and shower trays (they must be connected with metal conductors to water pipes);
• metal housings of power outlets built-in or installed in dropped ceilings made with the use of metal;
• metal cases of household air conditioners.

Grounding switches are installed before the start of electrical work. The connection of the reinforcement of the foundations with the reinforcement of the walls must be carried out by the construction organization. Grounding switches are connected to pipelines by welding or a clamp. If it is not possible to use natural earth electrodes, artificial earth electrodes are used. These include a ground loop, which is created both for grounding electrical appliances and for lightning protection.

Lightning protection- This is a system of devices that ensures the safety of the building during electrical discharges in the atmosphere. Its main task is to change the trajectory of lightning discharges and extinguish its energy. Lightning protection includes:

• lightning rod - a device that receives a lightning discharge;
• current collector - elements of distribution of an electric discharge;
• earthing switch - a device for extinguishing an electric discharge.

There are several lightning protection schemes. Scheme based on a lightning rod includes a metal rod connected by cables to a ground electrode. Lightning rod based on "spatial grid" installed on the roof of the house. It distributes and extinguishes the discharge in the event of a direct hit. Scheme based on tension systems similar to the scheme of a rod lightning rod, but the conductors are stretched along the perimeter of the protected zone.

All of the above structures are made of steel rods, ropes or steel meshes (at least 6 mm in diameter). Elements in nodes are connected by welding. The design of rod lightning rods is the most common, since they are the easiest to manufacture and ensure the reliability of the system.

Lightning rods based on tension systems are used when constructing roofs of complex shape. Spatial mesh requires more material and is more difficult to install. This type of lightning rod is appropriate if the roof of the house is higher than other objects located within a radius of 50 m.

Absolutely any suburban a private house must have a ground loop to protect a person from injury electric shock. The biggest danger is represented by such devices - where electricity and water are combined. At your dacha, this is the boiler from which you take a shower, washing machine, kettle, pump, septic tank, dishwasher: all these you use daily and even don't think about how dangerous it is without grounding. If 380 volts are brought into your house, then re-grounding is a must!

Ground loop country house we perform as follows: first, a trench one bayonet wide is excavated in the form of an equilateral triangle to a depth of 0.5 m. The length of the sides of the triangle is 1.5 meters. Along the edges of the triangle, vertical ground electrodes made of a steel angle 50x50x5 are hammered to a depth of more than two meters. The structure is scalded with horizontal ground electrodes in the form of a 40x4 steel strip, which is removed from the contour and fixed on the facade of the building. At the edge of the strip, an M8 bolt is welded through which, using a special cable connecting lug, by crimping, there is a transition to a copper wire PV-1 (PV-3 or PUGV) with a cross section of at least 10 square millimeters. All connections are made only by welding, and treated with mastic against corrosion. Such grounding will serve you for decades. Ultimately, the ground wire is connected to the main ground bus (GZSH). Then comes the next crucial moment - the work of connecting the grounding in the shield. Need to choose correct system electrical installation grounding. The following systems are currently in use: TN (with subsystems TN-C, TN-S, TN-C-S) and TT. Contact us and we will professionally select the most suitable grounding system for your home.

If your home is at risk of being hit by lightning, then we can protect it too. Nowadays, two lightning protection systems are used - active and passive. The second one is most often used. We install lightning protection systems on any type of roof: metal tiles, ondulin, slate, tiles, soft roof and iron. We also carry out the installation of ready-made lightning protection kits from leading world manufacturers.

In a passive lightning protection system, a special lightning rod is mounted on the roof ridge. The descent from the roof along the facade is carried out by a galvanized steel conductor on special remote brackets. Through the down conductor, lightning enters the ground loop and the charge is extinguished in the ground at a depth. In an active lightning protection system, different manufacturers use various principles work: for example, active lightning rods with electronic devices are used that emit a high-voltage pulse of a certain frequency and amplitude directed towards lightning. Having captured the lightning discharge, it is also directed to the ground through the down conductor.

We also strongly recommend installing a surge protection device (SPD) to protect your electrical wiring and expensive equipment from lightning strikes into the power grid or interference resulting from this natural phenomenon.