The need for lightning protection devices. Do you need lightning protection? What is passive lightning protection

Lightning protection of buildings and structures is a rare system on the roofs of new and modern houses. This is due to a person’s confidence that a lightning bolt will strike anywhere but nearby.

When lightning strikes a roof, pipes or other elevated structures adjacent areas lightning overvoltage and electromagnetic pulses occur, which pose a threat to any electrical appliances included in electrical network alternating current.

Features of the lightning protection system

Lightning protection of an object is a set of measures and devices that can protect detached buildings and structures from lightning strikes.

There are three main factors affecting lightning:

• direct lightning strike on the roof of a building;
• impact on nearby communication and technical facilities;
• strike into the ground near a house or into a nearby object with further discharge into the ground.

In the first case, a direct blow can lead to serious damage - a sharp increase in temperature and baking of roofing materials, and in rare cases, even fire wooden structures and roof slabs. The main destructive factor is hidden in the shock wave generated by lightning.

When a strike occurs on communication objects or power lines, a lightning impulse current is created, which enters the home through electrical wires and pipes. This can lead to electric shock, damage to cable sheaths and cores, equipment failure, and internal system failure.

In the third option, the discharge hits the ground. If the ground resistance is high or due to other factors, the voltage can go through the ground electrode into the neutral wire back into the house. In private houses, the zero is grounded in village transformer substations. A case may arise when the voltage is both in phase and zero, which will also lead to breakdown of devices and equipment. But this is a rare case: as a rule, the current, entering the ground, spreads evenly.

Important! The most terrible consequences are the destruction or fire of the roof as a result of direct lightning strikes.

Types of lightning protection

According to the design of the protection system, there are:

• external;
• internal.

Each system has its own purpose, and they must be used in combination to eliminate all three factors of lightning damage.

An external lightning protection device for buildings and structures is mounted on roofs, nearby extensions, structures and consists of an air terminal, a down conductor and a grounding conductor.

Their main function is to divert the current discharge into the ground, preventing it from reaching the roof surface. The discharge enters the ground electrode through the down conductor and then spreads into the ground.

The internal type of lightning protection system consists of installing a device inside a building and serves to protect against surge voltages.

1. There are the following types of internal devices:
2. Voltage control relay with the ability to manually adjust the minimum and maximum voltage levels in the network. If critical points are violated, the device turns off the voltage. Can be installed throughout the house or separately for each device. The simplest and cheapest option.
3. Voltage regulator.

Phase control relay (for three-phase voltage). Refers to microprocessor devices.

Types of lightning rods

• According to design and material, lightning rods are:
• rod - separately located and on the roof;
• cable;

mesh - on the roof. The most common and frequently encountered are rod and cable, which are used on simple and complex two pitched roofs . If the roof structure is multi-level, it is recommended to use a combined system using two different types

receivers.

Rod lightning rods

The main feature is a long vertical pin, the main function of which is to receive a lightning strike. The device must be highly durable, resistant to precipitation and aggressive environments, but be light and easy to install.

Depending on the roof area, several such masts can be installed. Such structures must be installed on the highest point of the roof or wall. It is necessary that the pin rises at least 1.5 m. You can install such a system separately from your home. In the second case, the mast can reach several tens of meters. The rod structure forms an imaginary cone around the housing - a zone of protected space.

The size of the mast can be determined from the diameter of the cone and its height.

Cable lightning rods The horizontal mounting system presents a tensioned along the entire length of the ridge. The lightning strike is absorbed by the cable. You can install pins at different ends of the roof and stretch a cable between them, resulting in a combined type of protection. This is suitable for roofs where the length is many times greater than the width. The diameter of the cable must be at least 12 mm. The thickness of the cable is determined by the length of the installation span.

The system has special requirements for the strength of the tension element, which is associated with wind loads and icing. To avoid damage to the system, it is recommended to install several intermediate fasteners along the entire length of the roof.

An economical and simple option is obtained by using steel wire rod instead of a cable, which is easy to install (can be welded to structures and to each other) and is quite durable. To fasten the wire, you can use special bolt clamps - terminals.

Mesh lightning rods

The system is horizontal, mounted on flat roofs. The mesh is made from rolled wire with a diameter of 10 mm or steel strip of any diameter. Such receivers are mounted by welding and require a large consumption of material, so the system is considered very labor-intensive to install.

It can also be installed on pitched roofs. In this case, the mesh is mounted around the perimeter of the plane. This is the main reason why cheaper, simpler and safer systems are installed on pitched roofs. This type of protection is suitable for installation on the roofs of schools and kindergartens, institutes and government agencies. Considered the most reliable.

Down conductors

This element connects the lightning rod to the ground electrode. For manufacturing, steel wire with a diameter of 6–10 mm is used; a steel strip or a half-inch water pipe is also suitable.

It is very important to make a strong and reliable connection between down conductors and lightning rods with grounding conductors. The strongest connection is considered to be a welded or bolted connection. To make the down conductor invisible on the facade, it can be painted in the color of the cladding or finishing of the house. Along the entire length of the descent it is necessary to make intermediate fastenings at a distance of 1.5 - 2 meters.

Grounding

The device is a metal structure buried or driven into the ground and ensuring good contact of the system with the ground. In wet soils, there is no point in equipping a ground electrode deeper than 80 cm. As a rule, a steel rod 18–20 mm or an angle 40–50 mm, or a steel strip 40 mm wide is used. The length of the ground electrode must be at least 3 meters.

The design may have the shape of a triangle or resemble an inverted letter “W”. The connection of the grounding elements is carried out by welding or bolting. The design must be reliable for many years, not weaken and have no backlash.

Important! If there is a ready-made grounding loop near the house, lightning protection for buildings can be connected to it.

Installation of lightning protection

Installation should begin with the installation of lightning rods. When working at height, follow safety rules. If you plan to do the installation yourself, start with a primitive project. When you are going to connect to a finished ground loop, plan the installation taking into account this connection location.

Always follow the rule: down conductors should be as short and straight as possible. Get out the best shortest distance from the lightning rod to the grounding conductor.

Note! If you are not confident in your abilities, entrust the installation of lightning protection to professionals. Specialists will complete the project and conduct pre-operational tests.

Test and inspection

Before using lightning protection, you must check the following system elements:

1. Welding joints for strength. This is done visually or by tapping with a hammer.
2. Bolted connections and ties. It is necessary to tighten all connections, especially those that will be in the ground or on the roof.
3. Ground resistance. Measured special device- insulation resistance meter.
4. The transition resistance of contacts and joints is measured with an insulation resistance meter or an ohmmeter.
5. Measuring current flow resistance with an insulation resistance meter.
6. Check for compliance with project documentation.
7. Reliability of fastening the lightning rod and intermediate clamps.

It is not worth saving money on protecting people from electric shock and the safety of housing and electrical appliances. The best option- a set of measures to prevent the consequences and destruction from lightning strikes.

The need for lightning protection of ground-based objects is prescribed primarily by classifying buildings and structures as lightning protection in accordance with RD 34.21.122-87 “Instructions for lightning protection of buildings and structures.” The instruction establishes the necessary set of measures and measures designed to ensure the safety of people (farm animals), to protect buildings, structures, equipment and materials from explosions, fires and destruction possible due to lightning. The requirements of the instructions are observed when developing projects for the construction of buildings and structures.

Today, the problem is often considered to be the owner’s desire to build a facility at the lowest cost, which pushes them to carry out construction without proper design study, with the involvement of unskilled third-party labor, as well as to use materials and equipment from “random” manufacturers.

Despite the differentiated approach to solving issues of providing lightning protection to buildings and structures, a number of conventions, uncertainties and ambiguous interpretations of a number of conditions in Table 1 of the current instructions for the installation of lightning protection create erroneous opinions in design decisions, which leads to either underestimation or overestimation of the requirements for lightning protection equipment buildings and structures. Today, the ambiguity of interpretations of RD also complicates the correctness and necessity of designing lightning protection. Ambiguous interpretation of lightning protection of architectural monuments based on the number of thunderstorm hours, uncertainty in clause 9 of Table 1 on lightning protection of small buildings, lack of practical instructions for lightning protection of metal building elements (roofing elements, etc.), use of grounding and, finally, lack of practice in applying IEC requirements – all this leads to a situation where the problem of lightning protection of ground-based objects is becoming global. Together with the lack of proper supervision, everything leads to the fact that often constructed objects suffer considerable losses, primarily of an economic nature. And the confidence that such a small structure is struck by lightning 1-2 times a century frees in most cases the need for lightning protection for residential buildings in rural areas, gardens and country houses.

Back in the 50s of the last century in regulatory documents regulating the requirements for lightning protection of buildings and structures, prescribed methods for lightning protection of houses in rural areas. A number of examples were given on reliable protection from direct lightning strikes. The types of lightning rods were indicated depending on the configuration and geometric dimensions. The types of materials from which lightning rods were made were given. Despite the requirements for the use of factory-made lightning protection elements, it was allowed to use lightning rods from improvised means to protect private households. Black iron with a minimum diameter of 6 mm was used as lightning protection elements. Down conductors and grounding conductors were also made from similar material and were laid over combustible building structures or placed in the ground, regardless of soil properties. In a number of cases, such methods of protection against manifestations of atmospheric electricity contributed to the independent equipping of buildings and structures of the agricultural complex, as well as residential buildings, mainly in rural areas, with lightning protection. This policy in the field of protection from atmospheric electricity was also partly due to the lack of the required number of organizations with sufficient practical experience in the field of lightning protection, publications on the study of lightning phenomena, installation of lightning protection, etc. In addition, first of all, the regulatory documents paid attention to the high-quality and mandatory implementation of lightning protection of government facilities.

Lightning is concentrated electricity, which is emitted by a thundercloud formed when high humidity air and sudden temperature changes. Lightning can overcome huge distances. A direct hit by a lightning discharge on an object causes heating to ultra-high temperatures followed by melting and even evaporation. Explosions can occur in structures due to a sharp increase in electrodynamic voltage. There is also a following Negative influence lightning discharge: the magnetic field provoked by the strike generates an electromotive force in closed circuits from metal structures, which, in turn, can cause sparks and intense heat, damage electrical installations and cause electrical shocks and other accidents to people. To prevent negative consequences from lightning strikes, it is necessary to provide a lightning protection device.

What is lightning protection of buildings and structures

Briefly, this is a set of actions and measures, as well as various protective devices to prevent accidents and fires in buildings and structures for residential and industrial purposes when they are struck by lightning.

Lightning protection measures are divided into external and internal. External protection consists of devices that intercept the electric charge from lightning and direct it to the ground through special down conductor channels. Such structures, installed in accordance with mandatory technical rules for lightning protection, reliably protect buildings and people inside them from damage.

External lightning protection measures for buildings and structures are divided into active and passive.

Passive protection is presented in the followingoptions:

• lightning protection mesh made of steel rods or wire rods, its use is permitted by all lightning protection standards, although at small excesses the mesh is not able to protect the roof surface reliably;

• metal rods (from one to several pieces) for receiving lightning strikes, a special cable connects them and grounding circuits - lightning rods;
• lightning-receiving metal cables.

All external lightning protection devices have the same standard and consist of three main parts: an interceptor of an electric discharge from a thundercloud - a lightning rod; a structural part that conducts electricity to the grounding conductors, and a grounding element that discharges the lightning charge into the soil.

The internal set of lightning protection measures is aimed at preventing damage that may occur to electrical equipment from a sudden surge in voltage in the network as a result of a lightning strike. The design of internal lightning protection is presented in two types: 1 – resistance to a direct lightning strike, 2 – resistance to an indirect strike passing near buildings/structures.

The secondary impact of lightning in the form of high potentials inside buildings is combated with the help of proper grounding. Electromagnetic induction in long iron structures is removed by installing metal jumpers. The introduction of high electrical potentials through communication inputs is prevented by valve-type arresters and special spark breakers, which are triggered by a sudden voltage surge.

The problem is also solved by prohibiting the entry of overhead lines for certain categories of structures and replacing them with underground cable entries.

Operating principles of lightning rods

The operation of these devices is based on the fact that lightning always strikes the highest and most prominent metal parts. All lightning rods have their own protection zone - this is an area that is protected from direct lightning strikes. When a discharge approaches, the very first lightning strikes the highest point of a building or structure, and the protection discharges electrical energy into the soil, and the protected object itself is not affected. In the case when the dimensions of the structure exceed the dimensions of the security zone of one lightning rod, additional devices of this type are installed (three or four interconnected rod devices with a common grounding).

The reliability of the protective zones provided by lightning rods, according to GOST, is divided into types: “A” – the degree of reliability is close to one hundred percent (99.5) and “B” – the degree of protection is from 95 percent. The protective zone itself is cone-shaped; its height and base area are determined by the dimensions of the building. The highest height of lightning rods allowed by building codes is 150 meters.

Lightning rod device

Any lightning rod consists of three main elements: a lightning receiver, conductor conductors (usually made of copper or steel) and a clamping circuit that transmits the accumulated charge into the ground to a depth of one and a half to three meters. The simplest form Such a device is a metal mast. The support posts of lightning protection devices are usually designed in the form steel pipes of the same diameter, as well as columns made of wood or reinforced concrete. Current-carrying parts of lightning removal devices are often attached to the structural elements of the structures themselves. Lightning traps on rod-type lightning rods are made of steel and must be at least 20 centimeters high.

Cable lightning rods are also called linear; they are a wire stretched between a pair of iron masts. Such a device allows you to collect all lightning strikes entering the protection field. Linear lightning rods are connected to the grounding loop with a cable large diameter made of copper or simple metal fittings.

On high-rise buildings Often a metal or reinforced concrete frame is installed as a down conductor.

Note! It is imperative to establish a reliable connection (provided by the snip) for all frame elements. Balcony railings, emergency evacuation stairs and other metal structural elements can also serve as down conductors. Conductor conductors are attached to the wall surfaces of structures using plastic clips; you can also use a cable channel, which will help increase the service life of the lightning conductor. When planning construction, you should provide for the presence of grounding loops with a pitch of 20-30 meters along the entire perimeter of the building.

Classification of objects to be protected

According to GOST standards, buildings and structures that need to be protected from lightning strikes are divided according to the degree of danger into ordinary and special objects. Common objects are considered to be residential and administrative buildings for commercial, industrial and agricultural purposes, the height of which does not exceed 60 meters. Special facilities include instructions for lightning protection of buildings and industrial structures:

• potentially dangerous to surrounding people and buildings;
• hazardous to the environment;
• capable, in the event of a lightning strike, of causing radiation, biological or chemical contamination - emissions exceeding sanitary standards (as a rule, this applies to state-owned enterprises);
• structures with a height exceeding 60 meters, temporary shelters, playgrounds, objects under construction and others.

For such objects, a lightning protection level of at least 0.9 is established. The owner of the structure or the customer of the construction can independently set an increased reliability class for the building.

Conventional construction projects, according to GOST, have four levels of reliability of protection against direct lightning strikes:

• first (at a peak lightning current of 200 kiloamperes), reliability – 0.98;
• second (lightning current 150 kiloamperes), reliability – 0.95;
• third (current 100 kiloamperes), reliability – 0.9;
• fourth (current 100 kiloamperes), reliability – 0.8.

Lightning protection categories

Guiding documents (RD) identify three main categories of lightning protection, determined by the average number and duration of thunderstorms in a particular area, the location of the building and the likelihood of it being struck by lightning, and the presence of fire and explosion hazard zones in the building.

The first category of road lightning protection includes objects industrial production with B-2 and B-1 explosion hazard categories. The second category of complete lightning protection is assigned to buildings with explosion hazard classes B-2a, B-1a and B-1b; such areas occupy at least 30 percent of the premises. The same level of protection against lightning strikes is assigned to fuel and lubricants warehouses, fertilizer warehouses, ammonia refrigerators and flour mills. According to the RD, in industrial buildings with lightning protection category 2, it is necessary to ground all electrical machine housings made of metal. When transitioning overhead lines to cable lines, it is necessary to install a jumper arrester on each phase.

Lightning protection category 3 is installed on structures with 3 and 4 degrees of fire resistance, as well as with an annual thunderstorm duration of at least 20 hours: children's institutions, schools, hospitals, entertainment centers, water towers, poultry farms and livestock complexes, as well as detached residential buildings buildings with a height exceeding 30 meters.

Regulatory documents on lightning protection

Due to the importance of protecting buildings and structures from lightning strikes, the state regulates the requirements for lightning protection by issuing regulatory documents:

• technical regulations;
• national standards - GOST (for example, GOST R IEC 62305-1-2010. Risk management. Lightning protection);
• instructions for departments and local guidance documents - rd (for example, “Instructions for lightning protection of buildings and structures” rd 34.21.122-87);
• rules for the construction of electrical installations - PUE (currently edition No. 7 is in effect).

ISO international standards are also used.

Electrical discharges accumulated in thunderclouds and brought to the surface of the earth by lightning can cause significant damage to buildings, structures and people and other objects located in them and nearby. To prevent negative consequences, lightning protection measures are applied, in the form of a system of various devices and special measures that minimize the possibility of electric shocks, accidents and fires.

Video

Lightning discharges can affect buildings and structures with direct impacts (primary impact), causing their direct damage and destruction, and secondary impacts through the phenomena of electrostatic and electromagnetic induction. During lightning strikes, high potential can be carried into buildings through overhead lines and various metal communications. The lightning channel has a high temperature (20,000 ° C and above), and when exposed to lightning, the resulting sparks and heating of the flammable medium to the ignition temperature cause fires in buildings and structures.
The need for lightning protection of residential and public buildings and structures are installed in accordance with the requirements of the “Instructions for the design and installation of lightning protection of buildings and structures” (SN 305-69), based on their purpose, the intensity of thunderstorm activity in the area of ​​their location, as well as the expected number of lightning strikes per year. Average thunderstorm activity in hours for one year is determined from the map given in SN 305-69 or based on data from local meteorological stations.

The following residential and public buildings and structures are subject to lightning protection:
1. Residential and public buildings or parts thereof, rising above the level of the general building mass by more than 25 m, as well as separate buildings with a height of more than 30 m, distant from the building mass by at least 100 m.
2. Public buildings of III, IV, V degrees of fire resistance (kindergartens and nurseries, educational and dormitory buildings of schools and boarding schools, dormitory buildings and canteens of sanatoriums, recreation institutions and pioneer camps, dormitory buildings of hospitals, clubs and cinemas).
3. Buildings and structures of historical and artistic significance, subject to state protection as monuments of history and art.
Specified in paragraphs. 1 and 2 buildings and structures are subject to lightning protection if they are located in an area where the average thunderstorm activity is 20 or more thunderstorm hours per year. The buildings and structures specified in clause 3 are required to be provided with lightning protection throughout the entire territory of the USSR.
The above residential and public buildings and structures in accordance with SN 305-69 are subject to lightning protection according to category III, i.e. with a device for protection against direct lightning strikes and against the introduction of high potentials through overhead metal communications.

The value of impulse resistance of each ground electrode from direct lightning strikes for residential and public buildings is taken to be no more than 20 ohms.

Buildings are protected from direct lightning strikes by lightning rods, which consist of lightning rods that directly absorb a lightning discharge, grounding conductors for discharging lightning current into the ground, and a down conductor connecting the lightning rod to the grounding conductor. Lightning rods are divided according to location into free-standing and installed directly on a building or structure; by type of lightning rod - rod, cable and special; according to the number of lightning rods operating together on one structure - single, double and multiple. If, for architectural reasons, installing lightning rods on a building is unacceptable, lightning protection of buildings can be carried out by applying a metal grounded mesh. To do this, use steel wire with a diameter of 6-8 mm, which is fixed to the roof in the form of a sparse mesh. The lightning protection mesh must have cells with an area of ​​no more than 150 x2, i.e., 12 x 12 or 6 x 24 m in size. This mesh on at least two opposite sides is connected to grounding conductors using down conductors made of the same wire and laid along the walls buildings. If the protected building is covered with roofing steel, then there is no need to install special lightning rods. It is necessary to lay a steel wire with a diameter of 6 mm around the building along the eaves and securely attach it to the metal roof at least every 15-20 m and install current conductors from this wire to the grounding conductors. Down conductors are attached to the roof using bolted clamps or welding. Chimney and ventilation pipes protruding above the roof must be equipped with rod lightning rods made of steel wire with a diameter of 6-8 mm protruding above the pipe by 30 cm and connecting them to the grounded roof. On metal pipes The installation of rod lightning rods is not required, but the pipes and the metal braces securing them must be securely connected to the roof or grounding system. Lightning rod lightning rods are made of steel rods of various sizes and cross-sectional shapes with corrosion protection. The minimum area of ​​the lightning rod must be at least 100 mm2, which corresponds to round steel with a diameter of 12 mm, strip 35 X 3 mm, corner 20 x 20 x 3 mm or gas pipes with the free end flattened and welded. The lightning rod lightning rod lightning rod should be constructed from a galvanized multi-wire steel cable with a cross-section of at least 35 mm2 (diameter 7 mm). Down conductors must be made of steel with a cross-section of 25-35 mm2 using steel wire (wire rod) with a diameter of at least 6 mm or steel of flat, square and other profiles. The current conductor of a cable lightning rod must be made of a cable with a cross-section of at least 35 mm2 or steel wire with a diameter of at least 6 mm.

In all cases, it is recommended to use metal structures of protected buildings and structures (columns, trusses, frames, fire escapes, metal elevator guides, etc.) as down conductors. In this case, it is necessary to ensure the continuity of electrical communication in the connections of structures and fittings, which, as a rule, is ensured by welding. Prestressed reinforcement of reinforced concrete columns, trusses and other reinforced concrete structures cannot serve as down conductors.

If buildings have an upper ceiling made of metal trusses, the installation of lightning rods or the application of lightning protection mesh is not required. In this case, the trusses are connected by down conductors to grounding conductors. In all cases, it is permitted to combine grounding conductors for protection against direct lightning strikes, protective grounding electrical equipment and grounding switch for protection against electrostatic induction.

If the building has a width of 100 m or more and is protected from direct lightning strikes by lightning rods installed on the building, lightning protection mesh or using metal roofing, then, in addition to external grounding switches, additional grounding switches should be installed to equalize the potential inside the building. These grounding conductors are made in the form of extended steel strips laid no more than 60 m apart and along the width of the building. The strips are accepted with a cross-section of at least 100 mm2 and are laid in the ground at a depth of at least 0.5 m. Each ground electrode is connected at its ends to the external contours of the ground electrode for protection against direct lightning strikes, and is also connected at intervals of no more than 60 m to down conductors from lightning rods.

Depending on the location in the ground and the shape of the electrodes, ground electrodes are divided into the following types:
recessed - made of strip or round steel. They are laid horizontally on the bottom of the pit in the form of extended elements or contours along the perimeter of the foundations;
vertical - from steel vertically screwed round steel rods and driven rods from angle steel and steel pipes. Screw-in electrodes are assumed to be 4.5-5 m long, and driven electrodes are 2.5-3 m long. The upper end of the vertical ground electrode rises from the ground surface by 0.5-0.6 m;
horizontal - made of strip or round steel. They are laid horizontally at a depth of 0.6-0.8 m from the ground surface in one or several beams diverging from one point to which the down conductor is connected;
combined - combining into common system vertical and horizontal grounding conductors.

The design of grounding conductors is adopted depending on the required impulse resistance, taking into account the resistivity of the soil and the convenience of laying them. SN 305-69 provides standard designs grounding conductors and the value of their resistance to the passage of current. All connections of grounding conductors to each other and to down conductors must be performed only by welding with a welding step length of at least six diameters of the round conductors being welded. Bolted connections can only be used when installing temporary grounding conductors.

Non-metallic vertical pipes of boiler houses and enterprises, water towers, fire towers with a height of 15 m or more are protected from direct lightning strikes. In this case, the value of the pulse resistance of the grounding electrodes is assumed to be 50 ohms for each current-current electrode. For pipes up to 50 m high, one lightning rod and one external down conductor are installed. When the pipe height is more than 50 m, at least two lightning rods and down conductors are installed, located symmetrically along the pipe. Pipes with a height of 100 m or more along the perimeter of the upper end are equipped with a steel ring with a cross-section of at least 100 mm2, to which at least two down conductors are welded. The same rings are repeated along the height of the pipe every 12 m.
For metal pipes, towers and derricks, the installation of separate lightning rods and down conductors is not required; just connecting them to a grounding conductor is sufficient.

Metal sculptures and obelisks (historical and artistic monuments) should be connected to grounding conductors with a pulse resistance value of no more than 20 ohms.

The protection zone is the space around the lightning rod in which a building or structure is protected from direct lightning strikes. There will be sufficient reliability of protecting an object from direct lightning strikes only if all its parts fall within this zone. The protection zone can be calculated analytically and graphically using formulas and nomograms. Protection zones can be formed by single, double and multiple rod lightning rods, as well as single and double cable lightning rods.

Rice. 4. Protection zone of four lightning rods in plan

The height of lightning rods is determined using a nomogram quite accurately and does not require mathematical calculations. For example, to find the height of a double cable lightning rod in Fig. 5 shows a nomogram constructed in such a way that the height of the lightning rod h is determined depending on the distance between the lightning rods a and on the value h0, which is the smallest height of the protection zone between two lightning rods (the height of the protected building) - g
The resulting height of the cable lightning rod supports must be increased by the height of the sag boom, depending on the span length. G1o the nomograms given in SN 305-69 can also determine the height of single and double rod lightning rods, as well as single and double cable lightning rods up to 60 m high.

Protection against the introduction of high potentials (atmospheric overvoltages) is arranged as follows. On the external wires of power lines with a voltage of up to 1000 V, lightning strikes cause overvoltage, and the transfer of high potentials through the wires into buildings can cause fires and accidents with people and animals. This can be prevented by installing arresters, spark gaps (5-8 mm) on the lines or by grounding the hooks and pins of insulators phase wires and wires of radio broadcasting, telephone and other networks. Such protection is mandatory for schools, nurseries, clubs, hospitals and other buildings with large crowds of people. Hooks on power poles must be grounded with a down conductor made of wire with a diameter of 5-6 mm, wound onto the hooks, and connecting neutral wire to the grounding connection with bolted tinned clamps.

If the inputs go to auxiliary premises (warehouses, sheds, etc.), then protection on the supports should be carried out for every 5 inputs to consumers, alternating them with unprotected supports. The distance between protected supports should not exceed 200 m (5-6 spans). Entry into the building can be made from an unprotected support, provided that it is located at a distance of no more than 30 m from the protected support.

The specified protective measures may not be implemented if the network low voltage shielded from lightning damage by tall trees, buildings, etc. or located in areas not subject to lightning damage. The possibility of refusing to implement the specified protection in each individual case should be decided by operating or design organizations together with representatives of energy supervision organizations. To prevent radio antennas from carrying high potentials, it is necessary to lay a current conductor along each rack, connecting one end to the ground electrode, and placing the other 10-12 mm from the antenna cable.

Protection of residential and public buildings from the secondary effects of lightning is not required.

Lightning protection is a set of measures aimed at ensuring the safe operation of buildings, structures and utilities when exposed to thunderstorm manifestations caused by a direct lightning strike and its secondary manifestations.

Remember:

Installing a lightning protection system ensures the safety of both the building and the people in the building.

Lightning protection of buildings and structures consists of: an lightning rod (lightning rod) and a down conductor (galvanized circle or strip).

The lightning rod receives the lightning discharge and transmits it through the down conductor to the grounding device.

The lightning protection system for a residential building differs from an industrial facility, not only in the scale of lightning protection, but also in its constituent elements.

Opportunity to get acquainted with current catalog products of the TerraZinc company. In the catalog you will find all the necessary lightning protection and grounding elements with brief description and important characteristics.

Opportunity to familiarize yourself with the current product catalog of the TerraZinc company, on the website page with a detailed description of all lightning protection elements. All elements are clickable, which makes it possible to familiarize yourself with a detailed description and technical characteristics selected element.

Opportunity to familiarize yourself with the current product catalog of the TerraZinc company, on the website page with a detailed description of all lightning protection elements. In the near future, work will be carried out on the village and there will be detailed description each grounding element.

Lightning protection of buildings

Let's consider lightning protection of buildings. Let's take .

For installation to the surface of the roof, facade, gutters and other structural elements of the building, lightning protection elements are used - clamps, clamps, etc.

The ground electrode serves as a grounding device. Grounding can be implemented various options, more information about grounding can be found in our article: grounding.

The result of high-quality grounding is the execution of an action - the discharge of the resulting charge into the ground.

It's interesting to know that active lightning protection is nothing more than a hyped myth. We will release a detailed article about this soon. Stay tuned.

Lightning protection of industrial buildings (industrial lightning protection)

Let's consider lightning protection industrial building , or any other large structure with a straight roof.

A significant difference is the presence of a straight roof; in this case, the method of placing the conductor is used (usually a galvanized circle Ø8 mm is used) in the form of a grid. This creates a kind of shielded barrier that prevents lightning from entering the roof of the building.

In this case, or is used.

The holders are placed over the entire roof surface at a distance of 0.8 to 1.2 meters from each other.

The main requirement, in addition to the relative position of the holders (according to TKP 366-2011), is maintaining the height. The conductor should not be closer than 110 mm. to the roof surface.

This requirement is met by the overall dimensions of the roof holder (code: 30000 or code: 30001) TerraZinc.

It is worth noting that this requirement (to maintain a height of 110 mm) is specified only in technical requirements Belarusian standards and in the requirements specified in the technical documentation of the countries of the former CIS. And yet, knowing the requirements, Polish and German manufacturers continue to produce holders of a much smaller height.

Under these conditions, when using such holders, when installing a galvanized conductor in a lightning protection system, it is necessary to use additional pads and extensions, which greatly increases the cost industrial lightning protection.

The Belarusian company TerraZinc LLC proposed a way out of this situation. The enterprise for the production of lightning protection and grounding systems, in April 2015, began producing roofing holders of its own production that meet all the requirements specified in the technical documentation.

Similar roof holders made in Poland:

All other lightning protection elements: lightning rods; fastening elements and clamps used for mounting the conductor to the facade of a building, etc., are similar to the lightning protection elements used for a residential building.

What effects does lightning have on unprotected objects?

Lightning is characterized by a direct strike - a powerful damaging factor that causes explosions, fires, death of people and animals, destruction (damage) building structures And engineering equipment. At direct blow The lightning current can reach up to 200 kA, the voltage can reach 1000 kV, and the lightning channel temperature can reach up to 30,000 0 C.

Secondary manifestations of lightning occur as a result of a direct or close (up to 1 km) lightning strike. Secondary manifestations mean carried electrical potential through the wires of power supply systems and metal pipelines, accompanied by overvoltage pulses up to 100 kV, and electromagnetic interference that interferes with the operation of highly sensitive equipment. With secondary manifestations, a person is injured by lightning current, damage and fire to the insulation electrical wiring, failure of electrical equipment, loss of databases and failures in automated systems.

Lightning protection price

To determine the cost of a lightning protection system, we need information:

1. building design;
2. photographs of the building from 4 sides;
3. overall dimensions of the building (length, width, height of the wall to the beginning of the roof, length of the slope, length of the ridge);
4. roof covering material;
5. ridge shape (semicircular/angular);
6. the presence of elements (dormer window, chimney, ventilation pipe, antenna, etc.) protruding above the roof (specify the distance);
7. material and size of pipes on the roof (diameter or perimeter, height);
8. presence of storm drains; location and diameter of drainpipes;
9. facade material (main wall material; insulation material and thickness);
10. the presence of snow retention, roof fencing and ladders for maintenance;
11. type of soil.

Use our service for .

It is necessary to refer to the accompanying documentation to answer what the price of lightning protection depends on, or more precisely to TKR 366-2011:

For buildings of the 1st level of lightning protection, the number of elements used in the lightning protection system will be greater and, accordingly, the price of lightning protection will be higher. And for Level 4 structures, the number of elements used is smaller and the price of lightning protection is correspondingly lower.

At the same time, regardless of the level of lightning protection, a large object requires a large amount of galvanized conductor (galvanized circle or galvanized strip).

And if there is a complex roof structure (broken roof, presence large quantity output pipes and receiving antennas and other protruding elements located above the roof) the number of lightning rods increases.

All these conditions will influence the formation of the price for lightning protection.

The price of lightning protection will depend on the number of elements required to provide lightning protection and grounding of the facility.

Specialists of TerraZinc LLC will quickly and free of charge carry out calculations and draw up a list of necessary elements for your building. They will also explain why these particular elements were chosen for lightning protection of your structure. And they will answer the question: lightning protection price.

If necessary, we will refer you to a friendly design organization (with a good discount), where they will draw up a project and issue the necessary set of accompanying documentation, in accordance with the legislation of the Republic of Belarus.