How to make grounding in a private house, in a summer cottage

Operation of modern household and computer equipment without grounding is fraught with its failure. A large part of our country, especially in rural areas, has old-style power transmission systems. In them, the presence of protective grounding is not provided or they are in such a state that simply do not meet the requirements of electrical safety. Therefore, the owners have to do themselves grounding of a private house or dacha.

What it gives

Protective grounding is necessary to ensure electrical safety in the house. Properly made, the appearance of leakage current, it leads to the immediate operation of RCD (damage to electrical insulation or when touching live parts). This is the main and primary task of this system.

The second function of earthing is to ensure the normal operation of electrical equipment. For some electrical appliances, the presence of a protective conductor in the socket (if there is one) is not enough. It is necessary to connect directly to the ground bus. For this purpose, there are usually special clamps on the body. If we talk about household appliances, then this is a microwave oven, oven and washing machine.

Few people know, but a microwave without a direct connection to the “ground” during operation can significantly phonate, the reception of the level of radiation can be life-threatening. In some models on the back wall you can see a special terminal, although the instructions usually have only one phrase: “grounding is necessary” without specifying exactly how it is desirable to make it.

When touching the body of the washing machine with wet hands, a tingling sensation is often felt. It is not dangerous, but unpleasant. You can get rid of it by connecting the “earth” directly to the housing. In the case of an oven, the situation is similar. Even if it does not “pinch”, a direct connection is safer because the wiring inside the unit works under very difficult conditions.

With computers, the case is even more interesting. By connecting directly the “ground” wire to the case, you can times raise the speed of the Internet and minimize the number of “hang-ups”. It’s that simple because of the direct connection to the ground bar.

Do you need grounding at the dacha or in a wooden house

In dacha settlements, it is necessary to do grounding. Especially if the house is built of combustible material – wooden or frame. The thing is about thunderstorms. In dachas, there are a lot of elements that attract lightning. These are wells, boreholes, pipelines lying on the surface or buried to a minimum depth. All these objects attract lightning.

If there is no lightning rod and grounding, a lightning strike is almost equivalent to a fire. There is no fire station nearby, so the fire will spread very quickly. Therefore, in conjunction with grounding do also make a lightning rod – at least a couple of rods a meter long, attached to the ridge and connected with steel wire to ground.

Earthing systems of a private house

In total, there are six systems, but in individual construction is used, mainly only two: TN-S-C and TT. In recent years, the TN-S-C system has been recommended. In this scheme, the neutral at the substation is blind-earthed, and the equipment has direct contact with the ground. To the consumer, the earth (PE) and neutral/zero (N) are carried by a single conductor (PEN), and at the entrance to the house it is again divided into two separate conductors.

In this system, a sufficient degree of protection is provided by automatic circuit breakers (RCDs are not necessary). The disadvantage is that if the PEN wire burns out or is damaged in the section between the house and the substation, phase voltage appears on the earth bus in the house, which is not disconnected by anything. Therefore, PUE imposes strict requirements to such a line: there must be mandatory mechanical protection of the PEN wire, as well as periodic backup grounding on poles after 200 m or 100 m.

However, many power lines in rural areas do not meet these conditions. In this case, the TT system is recommended for use. Also this scheme should be used in detached open outbuildings with an earthen floor. In these there is a risk of touching the earth and the ground at the same time, which can be dangerous with the TN-S-C system.

The difference is that the “earth” wire to the panelboard comes from an individual ground loop, not from the transformer substation, as in the previous scheme. Such a system is resistant to damage to the protective conductor, but requires the mandatory installation of RCDs. Without them, there is no protection against electric shock. Therefore, the PUE defines it only as a backup, if the existing line does not meet the requirements of the TN-S-C system.

Earthing device of a private house

Some older power lines have no protective grounding at all. All of them must be changed, but when this happens is an open question. If you have exactly such a case, it is necessary to make a separate circuit. There are two options – to make grounding in a private house or dacha yourself, with your own hands, or to entrust the execution of the campaign. Campaign services are expensive, but there is an important advantage: if in the process of operation there are problems caused by improper functioning of the grounding system, the company that made the installation will compensate for the damage (must be spelled out in the contract, read carefully). In the case of independent execution, everything is on you.

The grounding system of a private house consists of:

• grounding pins,
• metal strips, they combine them into one system;
• line from the grounding loop to the electrical panel.

From what to make grounding pins

As pins you can use a metal rod with a diameter of 16 mm or more. And you can not take rebar: the surface of it has a hardened surface, which changes the distribution of the current. Also, the hardened layer in the ground is destroyed faster. The second option is a metal angle with shelves of 50 mm. These materials are good because they can be hammered into soft soil with a sledgehammer. To make it easier to do this, one end is sharpened, the second is welded to a platform, on which it is easier to hit.

Sometimes use metal pipes, one edge of which is flattened (welded) into a cone. In their lower part (about half a meter from the edge), holes are drilled. When soils dry out, the distribution of leakage current is significantly worsened, and in such rods you can pour salt solution, restoring the work of grounding. The disadvantage of this method is that you have to dig/drill holes for each rod – you can’t hammer them with a sledgehammer to the required depth.

Depth of hammering the pins

Grounding pins should go into the ground below the frost depth by at least 60-100 cm. In regions with dry summers, it is desirable for the pins to be at least partially in moist soil. That is why angles or bars with a length of 2-3 m are mainly used. Such dimensions provide a sufficient contact area with the ground, which creates normal conditions for the dissipation of leakage currents.

What must not be done

The function of protective earthing is to dissipate leakage currents over a large area. This is accomplished by the tight contact of the metal earth electrodes – pins and strips – with the ground. This is why grounding elements are never painted. This greatly reduces the conductivity between the metal and the ground, the protection becomes ineffective. Prevent corrosion in the places of welding can be anticorrosive compositions but not paint.

The second important point: grounding should have a small resistance, and for this a good contact is very important. It is provided by welding. All connections are welded, and the quality of the seam should be high, without cracks, caverns and other defects. Once again we draw attention: grounding in a private house can not be done on threaded connections. Over time, the metal oxidizes, deteriorates, the resistance increases many times, the protection deteriorates or does not work at all.

It is very unwise to use pipelines or other metal structures in the ground as an earth electrode. For a while, such grounding in a private house works. But over time, the joints of pipes due to electrochemical corrosion activated by leakage currents, oxidized and destroyed, the grounding is inoperable, as well as the pipeline. Therefore, it is better not to use such types of earthing devices.

How to do it correctly

First, let’s understand the form of the earthing electrode. The most popular – in the form of an equilateral triangle, in the tops of which the pins are driven. There is also a linear arrangement (the same three pieces, only in a line) and in the form of a contour – the pins are driven around the house with a step of about 1 meter (for houses with an area of more than 100 square meters). The pins are connected to each other with metal strips – metal ties.

Procedure

From the edge of the house scarp to the place of installation of the pins should be at least 1.5 meters. On the selected site dig a trench in the form of an equilateral triangle with a side of 3 meters. The depth of the trench is 70 cm, width – 50-60 cm – so that it was convenient to cook. One of the tops, usually located closer to the house, connect to the house trench with a depth of at least 50 cm.

In the tops of the triangle are hammered pins (round bar or angle length of 3 m). Above the bottom of the excavation leave about 10 cm. Note that the earth electrode is not brought to the surface of the ground. It is located below the ground level by 50-60 cm.

To the protruding parts of the rods / angles weld the metal bond – a strip of 40 * 4 mm. The created earth electrode is connected to the house with a metal strip (40*4 mm) or a round conductor (cross-section 10-16 ^mm2). The strip with the created triangle of metal is also welded. When everything is ready, the welding places are cleaned from slag, covered with an anticorrosive composition (not paint).

After checking the resistance of grounding (in general, it should not exceed 4 ohms), the trenches are filled with earth. The ground should not contain large stones or construction debris, the earth is tamped layer by layer.

At the entrance to the house to the metal strip from the earthing switch weld a bolt to which is attached a copper conductor in insulation (traditionally, the color of grounding wires – yellow with a green stripe) with a core cross-section of not less than 4 ^mm2.

In the electrical panel grounding is connected to a special busbar. Moreover, only on a special site, polished to a shine and lubricated with grease. From this tire “earth” is connected to each line, which is distributed throughout the house. And the distribution of the “earth” separate conductor on the PUE is inadmissible – only as part of a common cable. This means that if your wiring is divorced with two-core wires, you will have to change it completely.

Why you can not do separate grounding

Redoing the wiring in the whole house, of course, long and expensive, but if you want to operate modern electrical appliances and household appliances without problems, it is necessary. Separate grounding of certain outlets is ineffective and even dangerous. And here’s why. The presence of two or more of these devices sooner or later leads to the output of the equipment included in these outlets. The whole point is that the resistance of the circuits depends on the condition of the soil in each particular place. In some situation, a potential difference occurs between the two grounding devices, which leads to equipment failure or electrical injury.

Modular Pin System

All the previously described devices – from hammered corners, pipes and rods – are called traditional. Their disadvantage is the large amount of ground work and the large area that is required when installing an earth electrode. All because a certain area of contact between the pins and the ground is required, sufficient to ensure normal current flow. Difficulty can cause and the need for welding – otherwise connect the grounding elements can not. But the advantage of this system – a relatively small cost. If you do the traditional grounding in a private house with their own hands, it will cost at most 100$. This is if you buy all the metal and pay for welding, and the rest of the work is done independently

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A few years ago, modular pin (prong) systems became available. This is a set of pins that are driven to a depth of up to 40 meters. That is, a very long earth electrode is obtained, which goes to depth. Fragments of the pin are connected to each other with the help of special clamps, which not only fix them, but also provide a high-quality electrical connection.

The plus side of modular grounding is the small area and less work that is required. A small pit with sides 60*60 cm and a depth of 70 cm, a trench connecting the earthing device to the house is required. The pins are long and thin, it is not difficult to hammer them into suitable soil. Here we come to the main disadvantage: the depth is large, and if you meet, for example, a stone on the way, you have to start over. And taking out the rods is a problem. They are not welded, and whether the clamp will hold or not is a question.

The second disadvantage is the high price. Together with the installation will cost you such grounding in 300-500$. Self-installation is problematic, as hammering these rods with a sledgehammer will not work. You need a special pneumatic tool, which learned to replace the perforator with an impact mode. It is also necessary to check the resistance after each hammered rod. But if you do not want to mess with welding and land works, modular pin grounding is not a bad option.