Electricity supply of a private house: a single-line scheme. Power supply scheme for a private house

Not so long ago, owners of private houses connected to the power lines independently. The controlling organizations needed only to apply, and also to install a counter. Today the situation has radically changed. To connect to the power grid, you need to provide a project describing the ways of supplying all the appliances installed in the house (boiler, column, etc.). That is, the package of necessary documents for obtaining permission documents must necessarily include a single-line diagram of the system that provides them. About how to make it up, and how to arrange electricity supply to a private house correctly, and we'll talk further.

The project of electrification of a country house. A three-phase or single-phase network?

Of course, before drawing any schemes and going through the connection, it will be necessary to decide on the type of electricity supply, its source, and so on.

In private houses, as in urban apartments, a three-phase or single-phase network can be used. Both kinds have both their shortcomings and virtues. Initially, any industrial network has three phases. In high-rise buildings they are usually distributed among the apartments. At the same time, due to the difference in the number of electrical appliances used, the load on the phase wires often varies. As a result, the neutral wire sometimes burns out. In a private house, such problems usually do not arise, since the owner alone, and therefore, control the load in the distribution of phases is much easier. However, if the network is misused, all sorts of problems - up to the failure of electrical appliances - can arise in this case. To prevent such trouble, you should use a stabilizer, which is very expensive. In addition, it will be necessary to purchase equipment and elements designed specifically for a three-phase line. That will also fly into a lot of money. Therefore, a three-phase power supply scheme for a private house should be used when there really is a need. That is, in the event that it is expected to install very powerful instruments or equipment - machines, electric stoves, etc.

The advantage of single-phase networks is the relative cheapness and ease of use. The disadvantage is not too high power. It is more expedient to mount such a network in small residential or cottage houses.

Autonomous power supply

One of the important conditions for comfortable living in any building is the constant availability of current in the network. However, unfortunately, when the power supply of a private house is produced from a common power line, there are often problems associated with interruptions in its supply. A good way out of this situation may be the additional use of autonomous power supplies. To such it is possible to carry:

• UPS. In the event of a power outage, this device starts to function instantly and automatically.
• Generator. Such equipment operates on gasoline, diesel or gas. Also can be turned on automatically. The operating time depends only on the amount of fuel. With sufficient power, the generator can supply even a very large house with electricity for a long time.

How to get permission to connect

So, with the number of phases, a variety of additional power supplies, etc., you are determined. What next? In what order is a private house connected to the power line? The power supply to suburban buildings is controlled by the network supplying company in whose area of responsibility they are located. To her specialists and will need to apply by collecting the necessary package of documents. Their list should be known in advance.

After receiving the documents, the grid company will prepare technical conditions for the electricity supply of the private house. Most likely, they will have to be coordinated with various related organizations. Further the contract is concluded. After the network is mounted, the representative of the network organization arrives at the site and performs its verification for compliance with the requirements set out in the technical conditions. The inspection is carried out with the participation of all interested parties. Rostekhnadzor is then given permission to operate the network.

Single line diagram

First, let's see what, in fact, is a drawing. A single-line scheme is, in fact, the same basic, but executed in a simpler form. That is, all the trunk lines, both single-phase and three-phase, are marked on it by one line. There is no detailed detail in such schemes. Therefore, they are compact and at the same time give a fairly clear idea of exactly how the power supply of a private house is being carried out.

There are some rules for drawing up such schemes, of which we will talk later. They are not particularly complicated, but they need to be known about them. Otherwise, the project will not be accepted.

Purpose of compilation and basic requirements

The single-line scheme of power supply for a private house is an important document, through which all installation work is carried out. It should be compiled in such a way that:

• The safety of using electrical equipment in terms of electric shock was ensured.
• It was guaranteed that there was no risk of fire in the home due to short circuits, melting of wires, etc.
• During the operation of the building, the people living in it had the opportunity to use all the modern powerful electric appliances they needed without problems.

These are the main requirements for this document.

What kinds exist

Such a simplified scheme of power supply of a private house can be:

• Executive. Most often this option is already in the process of operating the facility. For example, if you need to make any changes to the current system, or for some reason, there is a need to provide information to an energy sales company. Before drawing up the scheme, the line in this case is simply visually inspected.
• Estimated. Such a scheme is made before the installation of the system, for example, in a new house or with a complete replacement of old electrical wiring. In this case, all necessary calculations (loads, cable sections, etc.), as well as the selection of suitable equipment (protection devices, etc.) are made.

Compilation rules (symbols)

Of course, the linear scheme of power supply for a private house is drawn with all prescribed standards. The latter are defined by GOST 2.702-75 and have been in force since 1988. They indicate which symbols should be used to represent the elements of the wiring at home. To display a three-phase connection, the following methods can be used:

• A crossed out line with the number "3" next to the output or input,
• Crossed out by three oblique dashes straight line.

For the designation of devices, contactors, starters, shields, sockets, etc., exactly the same symbols as in any other wiring diagram are used (GOST 2.709).

What should be present

The single-line scheme of power supply to a private house must necessarily include such elements:

• Point of connection to the electric main;
• The brand of the input device and the rated current at the connection point;
• The cable brand, its cross-section and length (to within a meter);
• Values of voltage loss in lines;
• The calculated and actual power of the ASP, their cosφ and design current;
• The brand of protective devices and their rated current;
• Design loads;
• Boundary of the balance sheet;
• A kind of ATS cabinet with the indication of its operation mode;
• Used instruments of commercial accounting and control.

How to draw

Of course, you can draw a diagram on paper, using a pencil and ruler. However, in our time it's easier to do this on a computer or laptop. There is a variety of software with which the scheme of power supply of a private house can be made quickly and without problems. After drawing, it is simply printed on the printer. For example, the program "1, 2, 3 scheme" is designed to create a single-line circuit board, and Semiolog allows you to create all the necessary labels. You can download this software from the official site, which guarantees the absence of "garbage" and viruses. Installation and use are free. "1, 2, 3 scheme", among other things, allows:

• In accordance with the requirements to choose the housing of the electrical board;
• Equip it with modular apparatus;
• Determine the connection hierarchy of the latter;
• To form a complete scheme.

In the program database there are actual certified articles of the necessary equipment.

Calculation of loads

Thus, when compiling a single-line power supply scheme at home, it will be necessary to calculate the loads, voltage losses, determine the power of the equipment and the cross-section of the cables. About how this is done, and we'll talk further.

Residential private house, whose electricity can be produced both through a single-phase, and through a three-phase network, of course, will be equipped with a variety of electrical appliances. In order to calculate the load on the line, you should add their power and divide by the voltage. The result is the required current. Knowing it, you can determine from the special tables whether the network is overloaded and what cable is needed for wiring. Performing calculations, it is necessary to take into account the power of not only existing electrical devices, but also planned for purchase in the future.

To some very powerful home appliances, for example, to a washing machine, a boiler or an electric stove is best to stretch a separate cable. Often a separate highway is also used for office equipment. In case of using any professional equipment in the garage or farm building, as already mentioned, a three-phase power supply of the private house is used.

How to choose a cable for the network

For a single-phase connection, you need wires with three cores, for three-phase, - respectively, with five wires. When designing a project, it is very important to choose a cable of suitable cross-section (guided by the PUE). This indicator can be determined by special tables, depending on the current strength. The necessary diameter of the conductor is preliminarily calculated. This is done using the formula d = k × I + 0.005. Here k is a constant coefficient for the conductor metal. For example, for copper it is 0.034. The letter I denotes the strength of the current.

Sell wires, using as a measurement system is not a diameter, but a section. Therefore, further it will be necessary to define it. For this, there is the formula S = 0.785 × d2.

Preliminary calculation can be made based on the fact that per square millimeter of copper wire can be 10 A, aluminum - 7 A. In practice, the sockets usually use a wire of 2.5 mm ² , and for lighting 1.5 mm ² .

Selection of the input device

Connection of the power supply of a private house is carried out through so-called ВУ. They are metal enclosures in which devices intended for controlling the electrical network of a building are assembled. Models that perform, including the distribution function, are called ASP. Install the input devices either on the power line pole , or next to the building.

When choosing an ASP in a private house, the electricity supply of which must be safe and uninterrupted, it is necessary to take into account:

• The magnitude of the line voltage. To suburban homes, usually lines of 220 V.
• Frequency of current. This is a constant value and is 50 Hz.
• Neutral mode. This is the type of grounding. In the private sector, it is usually carried out according to the TN-C scheme. In this case, the zero and protective conductor are drawn in one conductor. Separation of them is carried out inside the VU.
• Characteristics of short-circuit current. In the calculation of wiring diagrams, a short circuit on three phase conductors under voltage is usually taken into account. Calculations are carried out according to special formulas.
• Installed power.

In TN-C systems at 220 V, a single-pole input circuit breaker is usually used, at 380 V - a three-pole circuit breaker. In the first case, the calculation of the power of the input device is calculated by the formula I p = P p / U fs cos φ (where U is the phase voltage, Pp is the calculated power, Cos is the active / reactive power). The input power for the 380 V network is given by the formula Ip = Pp / (√3xUhx cos φ) (where Uh is the mains voltage).

The rated current must be 10% higher than the rated current. Therefore, the final result is determined by the formula I tp = Ip × 1.1.

ATS shields

The power supply system of a private house usually includes this element. The ATS shields are designed to provide backup power when the mains voltage fails. Additional inputs of these devices can be connected to both the fixed network and the generator. There are such types of shields:

• With the priority of the first input. In this case, when the mains voltage disappears, the system automatically switches to the backup one. In the event of a current, the reverse process occurs.
• Without priority. Back to the main input when voltage appears on it automatically such devices do not switch. This procedure in this case is done manually.
• With sectioning. In such devices, power is supplied through a system of switches installed on the inputs. If a voltage drops out on any one of them, the third switch starts functioning, supplying voltage to the de-energized consumers from the working input.
• With the DSU. In this case, when the voltage drops out, a generator is started at both inputs. When the main power is restored, the system returns to its original state. Electricity supply of a private house using this option will be uninterrupted in any case.

Among the other things, ATS shields can also be executed. For a current of 25-160 A hinged models are used, for 160-400 A - outdoor. The cables are inserted and output through the hatch at the bottom of the housing. The equipment is installed inside the cabinet on a special panel.

Basic rules for wiring

Of course, the power supply of a private house with its own hands must be arranged in compliance with all the necessary rules. This concerns also such an operation as the routing of cables through the premises. Directly into the house, the wiring is wound through the hole in the wall. On the premises, it is best to pull the cables in tubes laid in the walls during construction. In this case, if necessary, you can easily replace any worn out wire. Each pipe must be filled with cable no more than 40%. This will ensure easy dismantling. Also, closed wiring is sometimes mounted behind hanging or tension ceilings, along walls covered with plasterboard on a frame, etc. Plastic or metal pipes are also used.

Internal power supply of a private house made of wood is provided by wiring of open wiring. Cables in this case are stretched in special channels made of plastic. The height of their position on the walls is not standardized. In one channel it is impossible to stretch simultaneously light, power and low-current wires. Junction boxes are installed in the junction points both in the open and in the closed system.