How to make lightning protection of a private house
Lightning possesses a huge destructive force, which is a big problem for mankind since ancient times. This is one of the most dangerous natural phenomena, which carries a threat to the health and life of people, as well as to their property. With the development of technology and the emergence of various wireless equipment, the risk of lightning strikes has increased. At the same time, modern scientific developments are successfully fighting it. When thunderclouds are approaching in the sky and lightnings pierce him, a warning and intelligent person will not be afraid of them, because he has previously protected his home from direct impact. So, a good host will certainly show interest in how to make lightning protection of a private house, will not neglect this simple, and at the same time brilliant invention of mankind.
- Lightning is a real threat
- Types, principle of lightning protection
- Lightning protection device
- Lightning rods: different types
- Functions and operation of the down conductor
- Lightning protection system grounding
Lightning is a real threat
It is important to know the nature of the occurrence of lightning. This is the basis of the protection system.
Lightning is not only fascinating, but also a very strong and terrible phenomenon. This is an impulse of electric current resulting from the accumulation of electric charge in thunderclouds. The current strength can reach 200,000 A. True, such lightnings are very rare, more often there are lightnings with a power of up to 100,000 A. On the globe, up to 200 lightnings are formed every second. And, although the probability of a lightning strike of just one house is very small, it is better to be careful than to regret later. Passing through different materials, an electric spark discharge leads to the formation of thermal energy, which is the cause of fires and destruction. This phenomenon is especially dangerous for wooden buildings, and most of the suburban houses and cottages are built from this material..
In this regard, homeowners have a question about the need to protect the house from lightning. Lightning protection of a private house is needed: it will protect the housing from fire. Moreover, the cost of the system will take a very tiny share in the construction estimate.
Types, principle of lightning protection
There are two types of building lightning protection systems:
- and active.
Passive system – a traditional protection system consisting of a lightning rod, down conductor and grounding. The principle of its operation is simple: a lightning rod catches a discharge, directs it using a down conductor to a ground electrode, which dampens it in the ground. It is necessary to take into account the material of the roof and the type of roof, so that depending on these features, the type of lightning protection is correctly selected and ensure its maximum reliability.
The principle of active lightning protection is as follows: a lightning rod ionizes the air around it, intercepting a lightning discharge.
The remaining elements of the active lightning protection system are the same as the passive, but its radius of action is much larger – up to 100 meters. In this case, protection is provided not only the house, but also nearby buildings. Such lightning protection of a country house is very common in many countries. But it costs more than a passive one.
Lightning protection device
Lightning protection is a protective measure that ensures the safety of buildings and the lives of people living in them from the damaging effects of a lightning strike. As a lightning protection of a building, lightning rods are used.
Lightning rod consists of 3 main elements:
- air terminal;
- down conductor;
- ground loop.
Lightning rods: different types
This is a metal conductor, which is installed on the roof of the house to receive a lightning discharge. It is important to install it at the highest point of the roof. In cases where the house is very large or has a complex structure, it makes sense to install several lightning rods.
The air terminal can have various types of design:
- Metal pin 0.2-1.5 meters long, mounted vertically at the highest point of the house. It can be a chimney, a skate of a roof or a mast of a television antenna. It is made of metal, less susceptible to oxidation under the open sky – copper or, for example, galvanized steel. The cross-sectional area of this type of air terminal should be at least 100 m2 (if its shape is round, a diameter of 12 mm will be sufficient). When using a hollow tube, the upward end must be brewed. This method is suitable for all types of metal roofing..
- Metal cable, stretched on two wooden supports 1-2 meters high along the ridge of the roof. To make the design more reliable, metal supports can be used, but in this case they will have to be isolated from the cable using insulators. This method is well used for wooden and slate roofs..
- Lightning protection mesh, fixed along the ridge of the roof of the house, with grounded down conductors extending over the entire surface of the roof, ideal for roofs made of tiles.
The scheme of a lightning rod based on a “spatial cell”
It’s important to know! Lightning rods must be connected to all metal objects on the roof: fans, gutters, stairs.
As an alternative to the construction of a lightning rod on the roof, you can use, for example, a nearby tree (if it is, of course, 10-15m higher than the house). The air terminal is mounted on its top so that it is at least half a meter higher than the crown.
Further, the air terminal is connected to the down conductor.
Functions and operation of the down conductor
A down conductor is a part of a lightning conductor that is designed to divert the lightning charge from the air terminal to the ground loop. This is a 6mm thick steel wire welded to an air terminal, which, in conjunction with an air terminal, must withstand a load of 200 thousand amperes. It should be noted that the welding between these two components of lightning protection should be very reliable in order to exclude the weakening of the fastening or the gap between them (for example, from falling snow layer or strong wind).
The down conductor is lowered from the roof along the walls, nailing it with brackets, and sent to the ground, to the ground loop. If there are several down conductors, they are laid along the walls at a distance of 25 meters from each other, and as far as possible from windows and doors. It must be remembered that they can not be sharply bent (a spark discharge may occur and, as a result, ignition).
According to the rules, the down conductor should be as short as possible, but at the same time it must be laid closer to the places of greatest risk: the edges of the gables, sharp protrusions, dormers.
Lightning protection system grounding
Lightning protection grounding is a device that provides reliable contact of the down conductor with the ground. This is a normal circuit (as for household electrical appliances): three electrodes connected together and clogged into the ground. Well, if it is already available.
According to the rules, grounding of household electrical appliances and lightning protection should be common. And if it is not yet, it is not so difficult to manufacture – the design of the ground electrode is quite simple.
To do this, we take copper with a cross section of 50 mm2 or steel – 80 mm2. We dig a trench 3m long and 0.8m deep and drive steel rods at its ends (not completely). Using steel and welding, we connect these two rods. We weld a tap to the house to this design, to which we connect a down conductor. Paint the welding spots, then hammer the ground electrode to the very bottom of the trench.
It’s important to know! According to the rules, the ground electrode system is placed at a distance of no closer than 1 meter from the walls and at least 5 meters from the walkways, porch and walkways for pedestrians.
Methods of fixing system elements
Ropes and wires of lightning rods, as well as down conductors are installed in 2 ways:
- using a tension system;
- with remote clamps.
The tensioning system for installing lightning rods is carried out with the installation of rigid anchors at the base, on the walls and on the roof of the house, between which a cable is stretched. They are equipped with special tension clamps. The distance between the anchors can be up to 20-30 meters. On a flat roof, such lightning rods are equipped with distance elements (for example, plastic brackets) that hold them above the roof surface (at a certain distance).
On walls and on flat roofs, angular and self-locking clamps are used, which are fixed with dowels. On steep roofs of houses covered with ceramic tiles, it is much more difficult to fix the clamps. It uses ridge clips that fit in shape and size to the ridge tile. By the way, such clips can be selected in the color of the tiles, so as not to spoil the appearance of the roof when the cottage is lightning protected.
Lightning rods and down conductors must be connected with each other, as well as with the elements of the house using special screw clamps, which are made of brass, copper or galvanized steel.
Some lightning protection tips
Every year, before the start of the thunderstorm season, it is necessary to inspect all parts of the lightning conductor and their mounting locations so that, if necessary, they are replaced and painted.
Once every 3 years it is necessary to check the serviceability of the connections, clean the contacts, tighten the weakened connections or replace them.
Every 5 years, you need to open the grounding electrodes, check the reliability of their connection, as well as the depth of corrosion. If the section of a rusted part decreases by more than a third, it must be replaced.
We described the simplest yet proven lightning protection system of a private house. And, although at present lightning protection for private houses is not provided for by electricity supply projects (it is not necessary to have it available at the time the house is commissioned), each owner decides independently whether it should be installed.