Which pipes are lightning protected. The need for lightning protection of buildings. What is external lightning protection

In St. Petersburg, it is customary to install active lightning rods. The entire installation takes about five hours (including driving deep ground electrodes). We ordered from a specialized company (StroyMaximum-STMX, read more on the website).
What prompted us to install professional lightning protection was the fact that in our cottage town (in the Priozersky district) in a little over two months, two houses with home-grown lightning protection burned down during a thunderstorm.
As the saying goes, God saves the safe.
In general, there is an interesting article: Statistics say that on a planetary scale, lightning strikes everything that is on the ground with an intensity of about a hundred beats per second! And about 2000 thunderstorms themselves rage on the planet at the same time. One of the results of this can be fires (only in our country, 7% of fires in residential buildings are caused by lightning)
Ask your friends who have recently built a country house if they have protected it from lightning. 90% of respondents will answer "no". The reason is ignorance of the possible consequences of such frivolity or a typical Russian "maybe". There are primary striking factors of lightning - this is a fire, destruction, as well as secondary ones - the drift of the induced potential, the appearance in the internal network of sources of consumption of electrostatic and electromagnetic induction. Lightning is a huge spark that has a complex trajectory. Only 25-30% of lightning goes from the cloud to the ground. Very often we see a lightning discharge that has arrived from somewhere on the side, and the place of its origin can be located several kilometers from the place of impact. External lightning protection
A lightning rod is a device of three main elements: a lightning rod that receives a lightning discharge; a current collector, which should direct the received discharge to the ground, and a ground electrode, which gives a charge to the ground. The lightning rod can be in the form of a metal pin (rod), stretched along the ridge of the roof of a metal cable or a metal mesh made of reinforcement with a mesh spacing of usually 6-12 m. protection (this is everything that fits in a cone, the height of which is determined by the height of the lightning rod, and the diameter of the base is equal to the triple value of the height) hit the selected objects. Quite often you can hear the opinion that a metal roof (for example, a metal tile) allows you not to worry about lightning protection. A very dangerous delusion! It is supported mainly by the sellers of metal tiles themselves. A metal roof can act as a lightning rod. However, such protection will not save you from "serious" lightning, since the calculated thickness of the roof sheets must be at least 4 mm (and who uses this?). Lightning simply burns through sheets of smaller thickness. If there are protruding elements on the roof (for example, metal chimneys), lightning rods are mounted on them, protruding 0.2 m above the upper edge and securely attached to the roof metal. Once again we remind you: buildings with a metal roof must be equipped with a lightning protection system.
In addition to "mechanical" lightning rods, there are "physical" ones. The ability to artificially create a column of ionized air has long suggested the use of a counter lightning leader as a kind of lightning rod. The first ionization devices were based on the use of a radioactive isotope. When voltage was applied to such a device, a column of ionized air appeared, to which the leader from a thundercloud closed. Later, these devices were transformed into safe lightning rods that no longer operate from radioactive isotopes, but with the help of electronics (ERICO, USA). The devices turned out to be quite effective, there is experience of their use in the Russian Federation. The undoubted advantages of such lightning rods include an excellent opportunity to preserve the architectural appearance of the building without distorting it with visible additions. Many of us have observed how often lightning discharges near various high objects, not always hitting them. But few people pay attention to the fact that near high objects lightning is observed somewhat more often than in other places. This pattern is explained by the fact that the "counter leader" from high objects, as it were, attracts leaders from the cloud not only strictly above its top, but also from the peripheral parts of the cloud. It turns out that any mast (for example, a cellular communication) objectively attracts a larger number of lightnings to its location zone. grounding
In any case, both for "external" and "internal" lightning protection, the role of grounding is very important. Let's return to our instructions. She strongly recommends grounding lightning rods on the foundation reinforcement of the house or, if this is not possible, burying electrodes in the ground (by the way, it is not always possible to ground on the foundation reinforcement, there are some limitations: if the foundation is waterproofed with epoxy-based compositions or if the soil moisture is less 3%). The electrodes must be deepened so as to reach the moist soil layers. We are talking about the so-called step voltage, which in the immediate vicinity of the ground electrodes can be very significant and life-threatening. During a thunderstorm, it is not recommended to be closer than five meters from the ground electrode of the lightning rod, so as not to fall under the action of step voltage and touch voltage.

This topic is very relevant for Belarusian designers. I planned to write it about two years ago. During this time, a lot of things have changed, there were several publications on this topic from leading experts in the country, but, nevertheless, I want to express my humble opinion.

As you know, in the Republic of Belarus, instead of RD 34.21.122, from November 1, 2011, TCP 336-2011 (Lightning protection of buildings, structures and utilities) was put into effect.

As soon as this TAP came out, I began to study it diligently. At that time, I was already beginning to realize what design really is.

Now I have accumulated a lot of which are created specifically for specific design tasks. But, in this list there is no program for calculating the need for a lightning protection device.

In fact, I have such a program, or rather even two.

My very first program with which I started creating my personal programs was called: The program looked like this:

By the way, my name is on the top. I made this program when this blog did not yet exist, and the link is to my old blog, which I have not been doing for a long time and on which I practiced site building skills. There were 3 versions of the program where I fixed my mistakes.

The program could be freely downloaded on the Internet at the forum. I am one of the first who made such a program and put it on the Internet. Now the download links do not work, because. this program is not up to date and in some cases may not produce completely correct results.

The fact is that at that time the experts did not yet require a calculation, and the program simply turned out to be unnecessary.

After some time, I made a program for myself, which I called: I do not distribute this program, I will not even review it, since there is an official program from the Ministry of Emergency Situations of Belarus: And she looks like this:

I came across this program quite by accident. I bring my calculation to an expert, and they tell me why you manually calculated everything if there is a program developed by the Ministry of Emergency Situations

Personally, I have never used this program until now, but the fact that the program does not work correctly is 100%. There is a good review of their program on the Internet, where they give a bunch of errors, I hope these errors have now been eliminated.

On the website of the Ministry of Emergency Situations of the Republic of Belarus you can download the version of the program from 04/08/2015.

Before proceeding with the calculation, you need to understand the essence of the calculation. The calculation is done in order to understand what measures need to be taken to protect the building and people from lightning strikes.

The most expensive thing that may appear is an external lightning protection device. I do the installation of surge arresters and a potential equalization system in almost every project.

Initially, you do not take any measures to protect against lightning strikes. After calculating how you have determined that your risk is higher than acceptable, you begin to add various measures, thereby reducing the corresponding coefficients.

The employees of the Ministry of Emergency Situations considered that it was enough to calculate only R1. I, as a designer, am very happy, because they made it easier for us to calculate, but why shouldn't we count R2? The most obvious error that catches the eye is that when calculating the risk, they sum up all intermediate values from Ra to Rz. Not even in my first program.

The most important thing is that the examination accepts it, and it will not be difficult to select the necessary coefficients. Although, there were cases (not for me) when the expert forced to do external lightning protection, despite the calculation that did not require it.

My personal opinion.

With this calculation, you need to do the following:

Risk calculation

This does not apply specifically to the MES program. There is very little meaning from all the calculations. All calculations can be adjusted to the desired results, since not all experts are well versed in this calculation. This was especially true at the beginning.

The most difficult thing that I had while developing the program was the calculation associated with the shielding of cables and the choice of appropriate coefficients. I stupidly adjust these values to the desired result, since no one inside the building will shield the power cables.

I would like to ask a question to specialists, developers of TCP 336-2011: why did you not like table 1 in RD 34.21.122-87 (Instruction for lightning protection of buildings and structures)?

In my opinion, it is necessary to take this table and rework it. Add more objects.

For instance:

School - III class.

Residential building 16 floors - IV class.

One-story house - MOH is not required.

It is quite realistic to list 100 objects in the table, on which to make decisions on external lightning protection. Moreover, one object must be brought in different cases: in the city, in the countryside, perhaps even depending on the height of the building.

This will save time for both the designer and the checking expert.

Next time I will check if all the mistakes that I made in the RMZ v.1.03 program have been corrected.

In this article, you can discuss other problems and questions on TCP 336-2011.

Lightning protection of buildings and structures is a rare system on the roofs of new and modern houses. This is due to the person's confidence that a lightning discharge will strike anywhere, but not nearby.

When lightning strikes the roof, pipes and other towering structures of adjacent territories, lightning overvoltage and electromagnetic impulses occur, which pose a threat to any electrical appliances connected to the AC electrical network.

Features of the lightning protection system

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

There are three main impact factors of lightning:

direct lightning strike on the roof of the building;
strike at nearby communication and technical facilities;
a blow to the ground near the house or to a nearby object with a further discharge of the 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 a fire in wooden structures and roof slabs. The main destructive factor is hidden in the shock wave that lightning generates.

When hitting communication facilities or power lines, a lightning impulse current is created, which enters the housing through electrical wires and pipes. This can lead to electric shock to a person, damage to sheaths and cable cores, equipment breakdown and malfunction of internal systems.

In the third variant, the discharge hits the ground. With a large earth resistance or due to other factors, the voltage can go through the ground electrode to the neutral wire back to the house. In private houses, zero is grounded in the village transformer substations. A case may arise when the voltage is both in phase and at zero, which will also lead to breakdown of instruments and equipment. But this is a rare case: as a rule, the current, falling into 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 execution of the protection system there are:

external;
internal.

Each system has its own purpose, and they need to 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 outbuildings, structures and consists of a lightning rod, down conductor and ground electrode. Their main function is to divert the current discharge to the ground, preventing it from reaching the roof surface. The discharge through the down conductor enters the ground electrode and then spreads in the ground.

The internal type of lightning protection system is to install the device inside the building and serves to protect against surges.

There are the following types of internal devices:

Voltage control relay with the ability to manually adjust the minimum and maximum voltage indicators in the network. In case of violation of the indicators of critical points, the device performs a voltage shutdown. It can be installed on the whole house or separately on each device. The easiest and cheapest option.
Voltage regulator.
Phase control relay (at three-phase voltage). Refers to microprocessor devices.

Types of lightning rods

Lightning rods by design and material 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 gable roofs. If the roof structure is multi-level, it is recommended to use a combined system using two different types of 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 lightweight and easy to install.

Depending on the roof area, several of these 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 housing. In the second case, the mast can reach several tens of meters. The core 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.

Rope lightning rods

The horizontal mounting system is a tensioned steel cable along the entire length of the ridge. The lightning strike is taken over by the cable. It is possible to install pins at different ends of the roof and pull a cable between them, resulting in a combined type of protection. This is suitable for roofs that are many times longer than wide. The cable diameter 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 tension several intermediate fasteners along the entire length of the roof.

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

Mesh lightning rods

The system is horizontal, mounted on flat roofs. The grid is made of a wire rod with a diameter of 10 mm or a steel strip of any diameter. Such receivers are mounted by welding and require a lot of material, so the system is considered very laborious to install.

It can also be installed on pitched roofs. In this case, the grid 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 is considered 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 house decoration. Along the entire length of the descent, it is necessary to make intermediate fastenings at a distance of 1.5 - 2 meters.

grounding

Device - a metal structure buried or hammered into the ground and ensuring good contact of the system with the ground. With wet soils, it makes no sense to equip a ground electrode deeper than 80 cm. As a rule, they use a steel bar 18–20 mm or a corner 40–50 mm, a steel strip 40 mm wide. The length of the ground electrode must be at least 3 meters.

The design can be in the shape of a triangle or resemble an inverted letter "Sh". The grounding elements are connected 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 ground loop near the house, the lightning protection of buildings can be connected to it.

Installation of lightning protection

Installation should begin with the arrangement of lightning rods. Follow the safety rules when working at height. If you plan to install it yourself, start with a primitive project. When you are going to connect to a ready-made ground loop, plan the installation taking into account this connection point.

Always follow the rule: down conductors should be as short and straight as possible. Choose the shortest distance from the lightning rod to the ground electrode.

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

Test and verification

Before using lightning protection, it is necessary to check the following elements of the system:

Welding joints for strength. It is carried out visually or by tapping with a hammer.
Bolted connections and couplers. It is necessary to lock all connections, especially those that will be in the ground or on the roof.
Ground resistance. It is measured with a special device - an insulation resistance meter.
The transient resistance of contacts and joints is measured with an insulation resistance meter or an ohmmeter.
Measurement of current spreading resistance with an insulation resistance meter.
Check for compliance with project documentation.
Reliability of fastening of the lightning rod and intermediate clamps.

It is not worth saving money on protection against electric shock to a person and the safety of housing and electrical appliances. The best option is a set of measures to prevent the consequences and damage from lightning.

A direct lightning strike into a building or structure and discharges from electrostatic induction of clouds and from electromagnetic induction of lightning current inside a building can strike people in it, cause fires and explosions, destroy stone and concrete structures, split wooden poles of overhead lines and damage insulation. Protection against atmospheric electricity must be organized in accordance with the Instructions for the installation of lightning protection of buildings and structures.
Depending on the presence and class of explosive zones in a given building, one of the three categories of lightning protection is required or lightning protection is optional at all.
Lightning protection category I is used for industrial buildings with explosive zones of classes B-Ia and B-II. All these are not rural objects.
Category II lightning protection is used for industrial buildings with zones of classes B-Ga, B-Ib and B-IIa (provided that they occupy at least 30% of the volume of the entire building, and if less, then either the entire building is protected by category III, or part of category II), as well as open installations with zones of class B-Ig. Lightning protection for these outdoor installations is mandatory throughout the area, while category II lightning protection for buildings is required only in areas where there are at least ten thunderstorm hours per year. The division of the territory into areas with a different number of thunderstorms (thunderstorm hours) is given in the PUE and in the Instructions for the installation of lightning protection for buildings and structures. Category II lightning protection is performed for ammonia refrigerators, mills, factories or workshops for the production of animal feed, hay flour, TSM warehouses with gasoline, some fertilizers, pesticides.
For other industrial, residential and public buildings, lightning protection of category III should be built or not built at all, depending on the purpose and nature of the building, and sometimes also on the expected number of direct lightning strikes to this building per year.
This number is determined by calculation depending on the size of the building and the number of thunderstorm hours.
Regardless of the number of expected direct lightning strikes at 20 or more thunderstorm hours per year, category III lightning protection is constructed in the following cases: for outdoor installations of classes II ... III; for buildings of fire resistance degrees III ... IV - kindergartens, nurseries, schools and boarding schools, dormitories and canteens, recreational children's camps and rest homes; for hospitals, clubs, cinemas; for vertical exhaust pipes of boiler houses or industrial plants, water towers and silos at a height of more than 15 m from the ground. In areas with at least 40 thunderstorm hours per year, category III lightning protection is required for livestock and poultry buildings with fire resistance degrees III ... V: barns, calves and pigsties for at least 100 heads of all ages and groups of animals, stables for 40, sheepfold for 500 and poultry houses for 1000 heads (of all ages); for residential buildings - only at a height of more than 30 m (more than five floors), if they are located more than 400 m from the general array.
Category III lightning protection protects against a direct lightning strike and against the introduction of high potentials into the building through overhead electrical lines, as well as through other elevated metal communications (trestle pipelines, overhead railways).
These communications, when entering the building and on the nearest support, are connected to grounding conductors with a resistance of not more than 30 ohms. At the input, you can use a grounding device to protect against a direct lightning strike.
On overhead electric lines with a voltage of up to 1000 V, passing through an open area or along a street with one-, two-story buildings (if the line is not shielded by tall trees or houses), ground insulator hooks or pins of phase wires (including street lighting lines ) and a neutral wire at least every 200 m with thunderstorms of 10 ... 40 hours a year and at least every 100 m with a greater number of thunderstorms (more often, for example, to the west of Moscow). The resistance of the grounding conductor should be no more than 30 ohms, it is made on poles with branches to the entrance to the building, where there can be many people (school, nursery, hospital, club), or to livestock buildings, warehouses, as well as on the final poles of the lines, if from them an input was made into any building. At the same time, the previous grounding should be no further than 100 m from the end support with grounding during thunderstorms of 10 ... 40 hours per year and no further than 50 m, if there are more of them.
When lightning surges appear on the wires of the line, the insulators overlap on the surface with an electric discharge to grounded hooks, and only relatively small surges penetrate the houses. Only approaching a few centimeters to the wiring during a thunderstorm can be dangerous, for example, when trying to turn on or off the light, radio. And in the absence or improper implementation of lightning protection, there were cases of people being struck at a distance of 2 m from the wiring or more.
All of the above applies to both wooden and reinforced concrete supports. For those reinforced concrete poles where lightning protective grounding is not required, the fittings, insulator hooks or pins and lamps are neutralized. A steel rod with a diameter of at least 6 mm is used as a grounding conductor, which is attached to the hooks with a wire bandage, and to the neutral wire with a clamp. On reinforced concrete supports, support reinforcement is used, to which the upper and lower ground outlets are welded for attaching grounding hooks and for connecting to the ground electrode. Lightning protection grounding on the line is done more often than repeated grounding of the neutral wire.
To protect against a direct lightning strike, rod or cable lightning rods are used. A rod lightning rod is a vertical steel rod of any profile, mounted on a support standing close to the protected object, or on a tree. The distance from the support to the building is not standardized, but it is desirable that it be at least 5 m. The cross-sectional area of the rod, called a lightning rod, is usually at least 100 mm2, and the length is at least 200 mm It is connected to the grounding conductor with a down conductor made of steel rod with a diameter of at least 6 mm, but it can be used as down conductors for metal structures of protected buildings and structures with welding of their joints. These are metal trusses, columns, elevator rails, fire escapes.
For lightning protection, it is necessary to use as much as possible natural rod lightning rods: exhaust pipes, water towers and other tall structures located close to the protected object. Trees growing closer than 5 m from buildings of III...V degrees of fire resistance can be used as a support for a lightning rod, if a down conductor is laid on the wall of the building against a tree to the entire height of the wall, welded to the ground electrode of the lightning rod. However, it is allowed for any category of lightning protection to place lightning rods directly on the protected building without any additional measures. As a lightning rod, you can use a metal roof, grounded at the corners and along the perimeter at least every 25 m, or a grid of steel wire rod with a diameter of 6 ... grounded in the same way as a metal roof. Iron caps over chimneys or a wire ring specially applied to the pipe, if there is no cap, are attached to the grid or metal roof.
No special lightning rods are required if the roof covering consists of metal trusses or reinforced concrete, and the waterproofing and insulation are non-combustible (from slag wool, etc.). Farms are grounded.
It is possible to have one common grounding conductor for protection against a direct lightning strike, against the drift of lightning surges along overhead lines or other extended communications, and against electric shock. Chimneys of power plants and boiler houses or silos and water towers must have a lightning rod height above the chimney of at least 1 m. It is recommended to use a reinforced concrete foundation of the chimney or tower instead of a special artificial grounding device. For reinforced concrete pipes and towers, steel reinforcement serves as a down conductor, while for metal lightning rods and down conductors are not required at all.
On fig. 38 shows the protection zone of a single rod lightning rod with a height h. It is a circular cone with a vertex at a height h 0 1 and with a zone boundary at ground level in the form of a circle of radius r 0 . The horizontal section of the protection zone at a height h x is a circle with a radius r x . There is a narrower zone, in which the object is protected from a lightning strike with a probability of 99.5%, and a wider zone, where the probability of protection is 95%. Rural facilities generally require a wider protection zone. For it, the following relations take place: h 0 = 0.92h; r0 = 1.5h; r x \u003d 1.5 (h-h x / 0.92); h = 0.67r x + h x /0.92.

Rice. 38. Scheme of a single rod lightning rod and its protective zone

As grounding conductors for a lightning rod located on the roof of a protected building, it is possible to use ground electrode systems constructed for electrical safety reasons (repeated grounding of the neutral wire), and if they are far from the lightning rod or are absent at all (when power is supplied to the building via cables with plastic sheaths), then reinforced concrete the foundation of the building, connecting the down conductor from the lightning rod to the reinforcement of the foundation by welding. From each lightning rod on the roof ridge, two down conductors should depart along both roof slopes to their ground electrodes. If there is no reinforced concrete foundation, a special one is constructed in the form of two vertical rods with a diameter of 10 ... 20 mm and a length of 3 m, located at a distance of 5 m from each other and connected underground at a depth of at least 0.5 m with a steel strip with a cross section of at least 40x4 mm.
With a lightning rod in the form of a grounded metal roof or a mesh on a non-metal roof, the ground electrode is made in the form of a grounding steel strip 25x4 mm, laid on an edge along the building at a depth of 0.5 ... 0.8 m and at a distance of 0.8 m from the foundation. K all metal structures, equipment and pipelines located inside the building should be attached to these strips.
So that people and animals are not affected by step voltage, it is recommended to place concentrated lightning protection grounding conductors of all categories no closer than 5 m from roads and footpaths, from building entrances, in rarely visited places (lawns, shrubs). Down conductors should not pass near the doors or gates of livestock buildings. In case of forced placement of grounding conductors in frequently visited places, these places must be asphalted. For example, when placing a ground electrode along the barn wall, the width of the asphalt pavement must be at least 5 m from the walls.
Outdoor installations of class P-III, in which flammable liquids with a vapor flash point of more than 61 ° C are used or stored, are protected from a direct lightning strike as follows: the bodies of these installations or individual containers with a roof metal thickness of less than 4 mm are protected by a lightning rod (separately standing or installed on the protected structure), and the space above the gas pipes may not be included in the protection zone of the lightning rod. If the thickness of the roof metal is not less than 4 mm or, regardless of the thickness of the roof, the volume of individual tanks is less than 200 m3, then it is enough to connect them to the grounding conductors at least 50 m apart along the perimeter of the base.
Extended lightning rods (grounded cables made of stranded steel rope with a cross-sectional area of at least 35 mm2) are used to protect long buildings from a direct lightning strike. Then the height of the cable lightning rod is considered to be the height of the cable above the ground in the place where it is closest to the ground as a result of sagging Ht, and the sag is taken equal to 2 m with a building length of up to 120 m, i.e. Nopor = Ht + 2. At the level earth Ro = = 1.7 Nt. At the height Hx (wall height) Rx = 1.7(Hm + Hx/0.92), and if Hx and Rx are given (for example, half the width of the building), then you can find Hm = 0.6 RxHx/0.92.
Small buildings with a degree of fire resistance III ... IV, located in rural areas with an average duration of thunderstorms per year of 20 hours or more, are allowed to be protected from a direct lightning strike in a simplified way compared to lightning protection category III by one of the following methods.
1. A tree growing at a distance of 3 ... 10 m from the building is used as a support for the lightning rod, if its height is at least 2 times higher than the height of the building, taking into account the pipes and antennas protruding above its roof. A down conductor is laid along the tree trunk, which should protrude above its top by at least 0.2 m. a depth of at least 0.5 m (they are also grounded in three other versions of simplified lightning protection. All connections are bolted, not welded). The main simplification in this option is the absence of a check whether the entire structure is included in the protection zone of the lightning rod.
2. If the roof ridge corresponds to the maximum height of the building, a cable lightning rod is suspended above it, rising above the ridge by at least 0.25 m. The cable can be supported by wooden planks attached to the ends of the roof. With a building length of more than 10 m, down conductors from both ends of the cable are laid along the end walls or one roof slope from each end, and if the building is less than 10 m long, then only one end of the cable is grounded.
3. If a chimney rises above the ridge and other elements, a lightning rod is fixed on it, which rises above the chimney by at least 0.2 m. From it, one down conductor is enough for one roof slope.
4. The metal roof is grounded at one point, and all metal objects protruding above it are attached to the roof, and downpipes, metal stairs can serve as a down conductor, if they provide continuity of the electrical circuit.

Do you need lightning protection?

Lightning, atmospheric discharges are a constant and almost ubiquitous companion of people. Their terrifying power was presented to our ancestors as a manifestation of the will of the gods. In world science and practice, effective methods of protection against the consequences of atmospheric discharges have been developed. Lightning protection is a set of measures to protect the life and health of a person and his property. At the moment, lightning protection, as a set of norms, methods and means, is a dynamically developing part of world technology.

Lightning and its striking factors.

Atmospheric discharges have a crushing force and their various consequences pose a serious threat to human life and property.

There are several lightning theories, but the main thing is that a potential difference of up to 1000 kV in the clouds with respect to the earth's surface causes a monstrous discharge of up to 200kA, which is accompanied by flashes and thunder. The heating of the atmospheric discharge channel reaches 30,000 deg. The average duration of the discharge, the most common cloud-to-ground lightning strike, is approximately 60-100 µs. It is more convenient to analyze the variety of damaging factors and consequences using the example of a table.

Threat Manifestation	Affecting factors	Possible consequences
Direct lightning strike on a building	Discharge up to 200 kA, up to 1000 kV, 30 thousand o C	Damage to a person, destruction of parts of buildings, fires
Remote discharge during a lightning strike in communications (up to 5 km or more)	Introduced lightning potential through power supply wires and metal pipelines (possible overvoltage impulse - hundreds of kV)
Close (up to 0.5 km from the building) lightning strike	Induced lightning potential in the conductive parts of the building and electrical installation (possible overvoltage impulse - tens of kV)	Damage to a person, violation of electrical wiring insulation, fire, equipment failure, loss of databases, failures in the operation of automated systems
Switching and short circuits in low voltage networks	Overvoltage impulse (up to 4kV)	Failure of equipment, loss of databases, failures in the operation of automated systems

From the above, we can conclude:

lightning, lightning potential poses a real and diverse threat to human life and property.
The human environment, as it becomes saturated with sensitive modern electronic equipment, has become extremely vulnerable to the effects of atmospheric and switching overvoltages.

As an example, the following statistics can be cited: over 25% of insurance payments in Germany account for damage from lightning and surges.

The need for lightning protection and surge protection is beyond doubt for everyone who has witnessed the consequences of atmospheric discharges.

A short list of problems related to the security of existing structures, the design and implementation of lightning protection of buildings in the territory of the Russian Federation.

At their core, the problems of Russian lightning protection are of a regulatory nature. The norms in force in the territory of the Russian Federation in the field of lightning protection do not fully reflect the achievements of modern science and technology. Effective methods and means of lightning protection are most fully presented in the IEC (International Electrotechnical Commission) standards and confirmed by wide practical application in industrialized countries.

For convenient perception of the text of the article, it is necessary to give the functional names of the basic sections of the lightning protection system adopted in international practice.

With a very generalized comparison of world and Russian standards, a number of fundamental conclusions can be drawn.

According to the section of external lightning protection:

In contrast to the norms of the Russian Federation, the IEC standards have developed a detailed method of protection by applying lightning protection circuits (mesh) to complex roofs of buildings in combination with protection of protruding parts.
The Russian guiding document "Instructions for the installation of lightning protection of buildings and structures" (RD 34.21.122-87) does not fix the world practice of using anti-corrosion materials and prefabricated elements, including ground electrodes and bolted connectors made of galvanized steel in grounding devices.
The same instructions stipulate the unambiguous practice of receiving a lightning strike with a metal roofing. At the same time, in the IEC normative documents, this method is used only when there is no need to ensure the safety of this coating.

According to the section of internal lightning protection:

At the moment, the international concept of zonal surge protection for electrical installations of buildings, information and telecommunication systems, electronic equipment and terminal devices is practically outside the field of activity of Russian specialists.

The IEC standards carefully developed rules and recommendations for the use of surge arresters in accordance with the zonal concept of internal lightning protection, as well as requirements for them. At the same time, the new edition of the PUE contains only a fragmentary indication of the need to install arresters on the input electrical cabinets during the air input of the supply line.
The Russian standards have not developed a set of methods and means for protection against lightning and switching overvoltages of modern low-voltage networks, equipment and devices.

As a result, this is not an exhaustive list of the real problems faced by developers, contractors and property owners.

In the absence of practice of using prefabricated elements, it is possible to implement effective external lightning protection of cottages, estates and similar buildings only with the use of free-standing high rod lightning rods. As a rule, developers and owners are not satisfied with this decision, because. the architectural identity of the building is violated, and its implementation is associated with significant costs.

The use of a metal roofing (especially metal tiles) as a lightning rod can lead to deformation and destruction of the sheet material, as well as ignition of the underlying combustible materials of the roof structures.

Difficulties arise in the arrangement of external lightning protection on reconstructed industrial, public and administrative buildings. At such facilities, it is cheaper to perform external lightning protection and grounding, regardless of current-carrying building structures, than to determine their suitability and reconstruct. In conditions of practical unavailability of factory-ready elements on the market, it is difficult to effectively and economically implement lightning protection of these objects.

Parts of lightning protection and grounding devices made from improvised materials in construction conditions have, as a rule, a low durability, an insufficient degree of protection against a direct strike, and no means of protection against brought and induced lightning potential.

Public and industrial buildings of urban development, which are protected from direct lightning strikes using conductive building structures, as a rule, are equipped with electrical installations without internal lightning protection devices. Owners and operating organizations may incur significant costs to eliminate the consequences and cover damage from lightning and switching overvoltages in networks.

Every year, expensive and sensitive to impulse voltage information technology equipment, telecommunications and automation systems are increasingly used in everyday life, management, industry and communications. Their uninterrupted operation and safety require complex and high-quality equipment to limit lightning and switching overvoltages with rules of application, installation and operation that are understandable to specialists.

Under these conditions, the subject of a possible reduction in the risks of insurance companies, and, accordingly, the size of tariffs for real estate and property insurers, is of great interest.

Experts offer you to create a new level of security for the houses you live in, which you build, equip and design. Complex equipment with system equipment of the leading German manufacturer OBO Bettermann is a time-tested effective solution for lightning and surge protection.