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Today we will talk about how to protect a private house from a lightning strike.
What is lightning?
Many owners of private houses try to make their home as comfortable and safe as possible, but at the same time they forget about the possibility of a lightning strike at home.
Lightning is one of the most unpleasant phenomena that can cause tremendous damage to a home.
As you know, it is a high-power electrical discharge, so even if it enters the house indirectly, it can damage electrical equipment in the premises.
It is good if there is a tall building near the house, equipped with lightning protection.
In this case, you do not have to worry about the possibility of lightning entering the house, since such houses often have lightning rods with a large protection zone, which will cover the area with adjacent buildings.
A feature of lightning is the discharge to the highest point. Therefore, if the house stands on the outskirts, it is the highest point, unless, of course, a tree grows next to it, which is taller than the house.
But the tree is also not a guarantee of protection. The danger of a home being struck by lightning increases many times over if there are reservoirs, strong streams, and swampy areas near the house.
So, if a private house is not surrounded by high-rise buildings, it is better to be safe by providing a home with lightning protection.
Striking factors of lightning
But before you figure out how to protect your home from a possible lightning strike, you should consider the damaging factors of this phenomenon.
There are two of these factors.
Primary.
This is a direct lightning strike into the house, as a result of which it can get structural damage, there is a possibility of a fire. This factor is the most dangerous.
Secondary.
It is less dangerous for the house and residents. This factor is reduced to the appearance of electromagnetic induction in the wiring of the house during a lightning discharge near the house.
Due to induction in the wiring, there is a significant power surge that can damage all electrical appliances in the house that are connected to the network.
And if you can protect yourself from the secondary factor without additional equipment by disconnecting all devices from the network during a thunderstorm, then it is impossible to protect the primary factor in this way, you need to equip the house with lightning protection.
Ohio, a house that was struck by lightning.
Since lightning is just an electrical discharge, albeit of great strength, it acts like any other discharge, that is, it moves along the path of least resistance.
Ensuring this path is the task of lightning protection.
If lightning hits a house equipped with this type of protection, then the electric discharge through it will go into the ground without causing damage to the building.
In the people, such protection is called grounding the house, lightning rods, lightning rods.
As for the latter, the definition is not entirely correct, because thunder is just a sound accompaniment that occurs when lightning strikes.
Criteria and types of lightning protection
Now let’s analyze the types of lightning protection.
Here, this equipment has several criteria that divide it into types.
The first criterion is the method of protection.
According to it, lightning rods are divided into:
- Active;
- Passive.
Active appeared relatively recently. They have a lightning rod, which is discussed below, is equipped with a special ionizer, which “provokes” lightning with its impulses.
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In fact, this device specifically attracts lightning to itself, which completely eliminates the possibility of a secondary factor of lightning strike.
Passive ones are not equipped with anything like that, lightning can discharge on it, or maybe not. This type of protection is used everywhere.
Further, we will consider only such protection, since it is possible to equip the house with it yourself, but the equipment for active protection is installed only by specialists.
The second criterion is the types of protection.
According to it, lightning rods are also divided into two types – external and internal.
Everything is simple here – the outer one protects the house from the primary factor of lightning impact, and the inner one – from the secondary one.
And the third criterion is design features.
But here the division into types is more related to lightning rods. According to them, the lightning rod is divided into pin, cable and mesh.
Lightning protection design
Now, regarding the design of lightning protection, let’s talk only about the external one.
It consists of only three elements – a lightning rod, down conductors and a ground electrode.
Lightning rod.
It takes on a lightning discharge, so it is fixed on the roof of the house so that the receiver itself is the highest point.
The simplest is the rod type of the receiver.
A metal rod with a diameter of 10-18 mm and a length of 250 mm is considered standard.
You can also use a pipe, but only its ends must be welded.
The number of receivers is calculated from the size of the building. For small houses, one is enough, if the area of u200bu10bthe house exceeds XNUMX square meters. two rods are installed with a distance between them of XNUMX m.
So that the discharge through the receiver does not go to the house, it is fixed on the roof with wooden bars or special fasteners.
Some, in order not to spoil the appearance of the house, install the lightning rod on a separate support near the house.
Some, if possible, mount an additional lightning rod directly on the tree.
There is no particular difference, since even with a nearby lightning rod, the protection zone will cover the house.
The main condition for installing the receiver is that it should be located above the house, as well as other buildings near it.
Another type of lightning rod is a cable.
A cable is used, which is stretched along the entire length of the roof ridge and fixed on wooden supports. An important condition is the tension of the cable – it should not touch the roof.
The third type of receiver is a grid.
It is made from any wire (steel, aluminum, etc.) with a cross section of at least 6 mm.
It is stretched over the area of the entire roof, the cells of this grid should form a square of about 6×6 m.
At the same time, the mesh should also not touch the roof, it is fixed on wooden or special non-conductive supports at a height of 6-8 cm from the roof.
There are no strict requirements for the use of one or another type of lightning rod, any one can be used, they are all quite effective, so they are chosen at will.
Down conductors.
Further on the second element of this protection – down conductors.
Their main task is to transfer the discharge from the receiver to the ground electrode.
Most often, steel wire with a diameter of 6 mm or more is used as down conductors.
If the walls of the house are made of brick or foam block, in general, from any non-combustible material, then the down conductor can be fixed along the wall in any inconspicuous place, most importantly, not near windows and front doors.
It is possible to use a metal tape as a down conductor, but with a thickness of at least 2 mm and a width of 30 mm or more.
The down conductor is attached to the receiver using a welded, bolted or soldered connection.
The number of down conductors depends on the number of lightning rod ends.
If only one rod receiver is used, then one outlet is attached to it. When using a cable receiver, two outlets are already needed.
Also, two down conductors are used with a grid receiver.
Grounding.
The last element is the ground electrode. The simplest grounding conductor is two metal rods buried in the ground by 2-3 m.
The distance between them should be at least 3 m. These rods should be connected to each other by a jumper at a level of 0,5-0,8 m in the ground. The down conductor is connected to this jumper.
On soils with a high level of groundwater, it is better to use a horizontal position of the ground electrode at a depth of 0,8 m. In this case, a metal corner or strip with a width of 50 mm and a thickness of 4 mm should act as a ground electrode.
The grounding conductor is connected to the down conductor only by a welded joint.
Read on the topic – protection of electrical appliances with the help of special devices.
Features of installation of lightning protection
Based on the above, it can be understood that it is quite possible to make lightning protection yourself, having only the necessary materials.
To protect your home from lightning, you must first take measurements.
It is necessary to find out the height at which the receiver should be located, as well as determine the method of its attachment.
Then you need to calculate the length of the down conductor. Here it is important to take into account that the path of the lightning charge to the ground electrode must be as short as possible. Therefore, you should not make any contours, bends, etc. And even more so, it is impossible to form rings from the branch.
As for the ground electrode, it should be located at least 1 m from the nearest wall of the house. After all the calculations, you can proceed with the installation.
You need to start with the ground electrode.
If it is made of rods, it is enough to dig a trench 0,5 m deep and 3 m long.
At the edges of this trench, drive rods at least 2 m long into the ground.
Then, using a welding machine, weld a jumper to these rods.
If the ground electrode is horizontal, then you will have to dig a trench much deeper.
The next step is to install the receiver.
An important condition must be observed here – it should not come into contact with the roof of the house, therefore, to fix it, use only wooden supports.
Or you need to fix it directly to the non-conductive structures of the house.
Then a down conductor is attached to the receiver and the ground electrode, which can then be attached to the roof with special devices, and then to the wall of the house.
The down conductor can also be fixed to the receiver with the help of bolts, but to the ground electrode – only by soldering or welding.
It remains only to bury the trench dug in advance.
As for the installation of protection on a house with wooden walls, the principle is identical, but there is one condition – it is impossible to attach down conductors directly to the wall.
They should be located at a distance of at least 150 mm from the wall.
Internal protection of the house
It was all about the external type of protection. Finally, a little about the internal, because the external type cannot completely protect the building from the effects of lightning, so it is advisable to use both of these types.
So, internal protection protects household appliances from power surges that a lightning charge can create.
For internal protection, special surge protection devices (SPDs) are used.
A large number of such devices are produced with varying degrees of protection.
These devices are connected to the electrical network of the house and are installed in the switchboard at the entrance.
Only after installing this device it will be possible to say with confidence that the house is fully equipped with lightning protection.