Grounding in the country with your own hands. Electrode installation diagram
Dacha today is no longer a summer building with amenities in the yard, but actually a full—fledged suburban housing. Moreover, it is equipped with powerful modern appliances — a refrigerator, a washing machine, a microwave oven. All these mechanisms facilitate homework, but they are also objects of increased danger. In order to avoid fires and tragic cases, it is recommended to equip the grounding at the cottage with your own hands. The circuit diagram is not so complicated, and it is not necessary to invite specialists for installation.
The most common grounding system is a construction of three metal pins (electrodes). The rods are buried into the ground and welded together with a horizontal steel strip. The finished grounding circuit is connected to the power shield using a steel rod held underground.
Useful advice! The grounding circuit is not recommended to be installed in rocky and stone soils — the resistivity of the rock is too high.
The principle of operation of the grounding system
Residential buildings are usually powered by a single-phase 220 volt AC power grid. The operation of household mechanisms and installations is provided by an electrical circuit in which there are two conductors — a phase and a zero wire.
The design of each electrical appliance provides for the presence of insulation and fuses that protect a person from electric shock. Imagine a situation where unreliable contacts sparkled. The voltage in this case will fall on the body, for example, of a washing machine. The hostess, touching her faithful assistant with a wet hand, will receive a strong electric shock.
It is especially dangerous when metal structures with so-called natural grounding are located next to a faulty unit. These include:
- heating pipes and radiators,
- water supply,
- gas pipes,
- open reinforcement of reinforced concrete slabs.
Taking hold of the battery and the body of the machine at the same time, the person closes the electrical circuit to himself. The current will go towards zero potential (into the ground), including passing through the body. The nature of electricity is such that the flow of electrons, like a stream of water, moves through channels with the smallest resistance.
To protect the household from such accidents, they mount the grounding circuit at the cottage with their own hands. Whether the circuit of the device will fail, or the insulation will break through with a discharge, there will be no trouble. A pre—created grounding line will take the dangerous voltage to a point with minimal resistance, namely, into the ground.
Unacceptable grounding schemes
Some home craftsmen are convinced that water pipes and heating risers can be used to divert current. Such grounding in the country with your own hands can not be called a safety scheme. Pipes can be highly oxidized, or have poor contact with the ground. In addition, plastic connections are often included in the pipeline system, which will open the electrical circuit.
Many modern electrical appliances are equipped with a cable with a three-core plug. The same sockets are installed to them. The zero wire in the cable is indicated in blue, the grounding wire is yellow—green, the phase is any other than those mentioned.
Wanting to save money on the grounding device at the dacha with their own hands, the scheme is used as follows: a jumper is made in the outlet between the grounding and zero contact. However, such a project is extremely unpredictable. If there is a phase change or a bad contact of the working zero in any part of the circuit, a dangerous voltage will occur on the instrument body.
Some homeowners, having installed a special protective device (RCD) into the network, consider the problem solved. But the operation of the RCD will be correct only if there is grounding. Then, when the current leaks, the electrical circuit will immediately close, and the mechanism will work, turning off the power to the dangerous area.
Grounding in the country with your own hands. Outline of contours
The resistance of the current removal system should be less than the resistance of the human body. For calculations, the average value is less than 4 ohms. In the standards, there are values of permissible resistance in 0.5 ohms, 30 ohms, 60 ohms. But here, where we are actually talking about life and death, it’s better less than more.
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The grounding circuit must provide the minimum possible resistance and reliable contact with the ground. However, the soil has different resistivity. It depends on its composition:
- sand — 1000 ohm*m;
- chernozem — 200 Ohm*m;
- sandy loam — 150 ohm*m;
- loess loam — 100 Ohm*m;
- semi—hard clay – 50 Ohm *m;
- plastic loam — 30 ohm*m;
- peat or clay plastic — 20 Ohm * m.
We see that the layers with the lowest resistance values are at a considerable depth. The problem of successful grounding is solved in several ways:
- deeper immersion of the electrodes into the soil;
- adding additional vertical elements;
- increasing the contact area of the rods with the ground (using wider pins with a larger cross section);
- increasing the distance between the electrodes.
Basic grounding schemes in country houses
Useful advice! Metal elements acting as electrodes cannot be painted. This worsens their conductivity.
Installation of the grounding system with your own hands
For a detailed consideration, let’s take the grounding system at the dacha with our own hands, scheme No. 2 — a triangle with pins in the vertices.
Material for electrodes:
- steel corner with a width of at least 4×4;
- reinforcing bar with a section of 10-12 mm;
- metal pipe with a wall cross section of 3.0-5.0 mm;
- steel strip with a width of 50 mm.
Useful advice! The fittings should be smooth. The grooved surface does not provide a strong contact of the electrode with the ground. When clogging, voids are created that reduce the quality of grounding.
The length of the pins should be approximately 3 m. As a binding, you can use a metal strip with a cross section of 4 × 40 mm, or a rebar with a diameter of 14 mm. Welding is always used when connecting the contour.
The order of work
First, we select and clear a place on the site where the contour will be installed. It is optimal if the distance from the electrodes to the power cabinet is about 10 m. Further work is carried out in this way:
- we dig a pit as under a ribbon foundation, only in the form of an isosceles triangle. The depth of the trench is 1 m, the width is half a meter. The distance from the rod to the rod should be approximately 1.2 m. From one corner of the triangle we dig a ditch to the power shield;
- we hammer the electrodes into the vertices of the triangle. With a high density of soil, it will be necessary to drill pits;
Useful advice! If the pin cannot be immersed in the ground for the entire length, you can take shorter rods (2-2. 5 m). Then their number should be increased.
- the driven rods should be visible above the ground surface so that they can be connected with a tire. It is recommended to fill the pits with earth mixed with salt. This will greatly reduce the resistance of the electrodes. However, metal corrosion will go faster;
- we weld the binding to the rods, forming a triangle. From one electrode we lead the strip along the trench to the switch cabinet. The conductor is attached to the shield by means of a welded bolt;
- we check the resistance using an ohmmeter. If the indicator is less than 4 ohms, you can fill up the trench. If more, we drive in a few more electrodes and connect them with the previous ones. After that, the risk of electric shock from household appliances will be reduced to zero.