Not so long ago, the owners of private houses connected to power lines on their own. It was only necessary to submit an application to the controlling organizations, as well as install a meter. Today the situation has changed radically. To connect to the mains, you need to provide a project describing how to power all appliances installed in the house (boiler, column, etc.). That is, the package of documents required to obtain a permit must necessarily include a single-line diagram of the system that ensures their operation. We will talk further about how to compose it, and how to arrange the power supply of a private house correctly.
Country house electrification project. Three-phase or single-phase network?
Of course, before drawing any diagrams and going to make a connection, you will need to decide on the type of power supply, its source, etc.
In private houses, as well as in city apartments, a three-phase or single-phase network can be used. Both varieties have their drawbacks anddignity. Initially, any industrial network has three phases. In high-rise buildings, they are usually distributed among apartments. At the same time, due to the difference in the number of electrical appliances used, the load on the phase wires is often different. As a result, the neutral wire sometimes burns out. In a private house, such problems usually do not arise, since the owner is alone, and therefore, it is much easier to control the load during phase distribution. However, if the network is used incorrectly, various kinds of problems - up to the failure of electrical appliances - can also arise in this case. To prevent such troubles, you should use a stabilizer, which is very expensive. In addition, you will have to purchase equipment and elements designed specifically for a three-phase line. Which also costs a pretty penny. Therefore, a three-phase power supply scheme for a private house should be used when there really is a need for it. That is, if it is planned to install very powerful devices or equipment - machine tools, 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 country houses.
Autonomous power supply
One of the important conditions for comfortable living in any building is the constant presence of current in the network. However, unfortunately, when the power supply of a private house is made from a common power line,often there are problems associated with interruptions in its supply. A good way out of this situation may be the additional use of autonomous power sources. These include:
- UPS. In the event of a power outage, this device will start functioning instantly and automatically.
- Generator. Such equipment runs on gasoline, diesel or gas. It can also turn on automatically. The operating time depends only on the amount of fuel. With enough power, the generator can power even a very large house for a long time.
How to get permission to connect
So, you have decided on the number of phases, the type of additional power sources, etc. What's next? In what order is a private house connected to the power line? The power supply of suburban buildings is controlled by the network supply company in whose area of responsibility they are located. It will be necessary to contact its specialists, having collected the necessary package of documents. Their list should be known in advance.
After receiving the documents, the network company will prepare the technical conditions for the power supply of a private house. Most likely, they will have to be coordinated with various related organizations. Next comes the contract. After the network is installed, a representative of the network organization arrives at the site and checks it for compliance with the requirements set forth in the technical conditions. The inspection is carried out with the participation of all interested parties. Next, Rostekhnadzor issues a permit to operate the network.
Single line diagram
For starters, let's see what, in fact, is such a drawing. A single-line diagram is, in fact, the same principle, but made in a simpler form. That is, all lines, both single-phase and three-phase, are indicated on it with 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 how exactly the power supply of a private house is carried out.
There are some rules for drawing up such schemes, which we will discuss later. They are not particularly difficult, but you need to know about them. Otherwise, the project will not be accepted.
Purpose of compilation and main requirements
A single-line power supply scheme for a private house is an important document, according to which all installation work is carried out. You need to compose it in such a way that:
- The use of electrical equipment in terms of electric shock has been ensured.
- It has been guaranteed that there will be no risk of fire in the house as a result of a short circuit, melted wires, etc.
- During the operation of the building, people living in it had the opportunity to easily use all the modern powerful electrical appliances they needed.
These are the main requirements for this document.
What species exist
So simplisticthe power supply scheme of a private house can be:
- Executive. Most often, this option is already made during the operation of the facility. For example, if you need to make any changes to the existing system, or for some reason there is a need to provide information to the power supply company. Before drawing up the diagram, the line in this case is simply examined visually.
- Estimated. Such a scheme is drawn up before installing the system, for example, in a new house or when the old electrical wiring is completely replaced. At the same time, all necessary calculations are made (loads, cable cross-sections, etc.), as well as the selection of suitable equipment (protective devices, etc.).
Composition rules (symbols)
Of course, a linear power supply scheme for a private house must be drawn in compliance with all applicable 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 certain elements of the electrical wiring at home on the diagram. To display a three-phase connection, the following methods can be used:
- crossed line with the number "3" next to the output or input,
- a straight line crossed out by three oblique lines.
To designate devices, contactors, starters, a shield, sockets, etc., exactly the same symbols are used as in any other electrical circuits (GOST 2.709).
What should be present
Single-line power supply diagram of a private housemust include the following elements:
- point of connection to the mains;
- brand of input device and rated current at the connection point;
- cable brand, cross-section and length (accurate to the meter);
- voltage loss values in lines;
- calculated and actual power of the ASU, their cosφ and rated current;
- brand of protective devices and their rated current;
- calculated loads;
- balance sheet ownership boundary;
- a kind of ATS cabinet with an indication of its mode of operation;
- used commercial metering and control devices.
How to draw
Of course, you can draw a diagram on paper using a pencil and a ruler. However, nowadays it is easier to do this on a computer or laptop. There is a variety of software with which the power supply scheme of a private house can be drawn up quickly and without problems. After rendering, it is simply printed on the printer. For example, the program "1, 2, 3 scheme" is designed to create a single-line electrical panel diagram, and Semiolog allows you to create all the necessary labels. You can download this software from the official website, which guarantees the absence of "garbage" and viruses. Installation and use are free. "1, 2, 3 scheme", among other things, allows:
- according to the requirements, select the electrical panel housing;
- complete it with modular devices;
- define the connection hierarchy of the latter;
- form a finished scheme.
In the program databasethere are actual certified articles of the necessary equipment.
Calculation of loads
Thus, when drawing up 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 cable cross-section. How this is done, and we'll talk further.
A residential private house, the power supply of which can be carried out 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 lines, you should add their power and divide by voltage. The result is the required current. Knowing it, you can use special tables to determine if the network is overloaded and which cable is needed for wiring. When making calculations, one should take into account the power of not only existing electrical appliances, but also those planned for purchase in the future.
To some very powerful household appliances, for example, to a washing machine, boiler or electric stove, it is best to stretch a separate cable. Often a separate highway is carried out to office equipment. In the case of using any professional equipment in a garage or outbuilding, as already mentioned, a three-phase power supply to a private house is used.
How to choose a cable for the network
For a single-phase connection, you will need wires with three cores, for a three-phase connection, respectively, with five. When developing a project, it is very important to choose a cable of a suitable section (guided by the Electrical Installation Code). This indicator can be found in special tables, independing on the strength of the current. The required conductor diameter is preliminarily calculated. This is done according to 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 indicates the current strength.
They sell wires using cross-section rather than diameter as a measurement system. Therefore, it will be necessary to define it further. For this there is a formula S=0.785×d2.
A preliminary calculation can be made based on the fact that copper wire can have 10 A per square millimeter, aluminum - 7 A. In practice, 2.5 mm wire is usually used for sockets2, and for lighting 1.5 mm2.
Selection of input device
The power supply of a private house is connected through the so-called WU. They are metal cases in which devices are assembled designed to control the building's electrical network. Models that also perform the distribution function are called ASPs. Install input devices either on a power line pole or next to a building.
When choosing an ASP in a private house, the power supply of which must be safe and uninterrupted, you need to consider:
- The value of the line voltage. 220 V lines are usually connected to country houses.
- Current frequency. This is a constant value and is 50 Hz.
- Neutral mode. That's what they callgrounding type. In the private sector, it is usually carried out according to the TN-C scheme. In this case, the neutral and protective wires are pulled in one conductor. Their separation is performed inside the VU.
- Short circuit current characteristics. In the calculations of electrical circuits, a short circuit on three phase conductors under voltage is usually taken into account. Calculations are made using special formulas.
- Installed capacity.
In TN-C systems at 220 V, a single-pole incoming circuit breaker is usually used, at 380 V - a three-pole one. In the first case, the calculation of the power of the input device is calculated by the formula I p \u003d P p / U f × cos f (where U f is the phase voltage, Pp is the calculated power, Cos f is the active / reactive power). The power of the input device for a 380 V network is found by the formula Ip \u003d Pp / (√3xUhx cos f) (where Uh is the mains voltage).
The rated current must be 10% more than the calculated one. Therefore, the final result is determined by the formula I tr=I p × 1, 1.
ATS Shields
The power supply system of a private house usually includes this element. AVR boards are designed to provide backup power in the event of a power failure in the main source. Additional inputs of these devices can be connected both to the fixed network and to the generator. There are such types of shields:
- Priority to first input. In this case, when the voltage at the main input fails, it automatically switches to the backup one. In the event of a current, the reverse occurs.process.
- No priority. Such devices do not automatically switch back to the main input when voltage appears on it. 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. In the event of a power failure on any of them, the third switch starts to function, supplying voltage to de-energized consumers from the working input.
- FROM DGU. In this case, when the voltage is lost at both inputs, the generator starts. When the main power is restored, the system returns to its original state. The power supply of a private house using this option will be uninterrupted in any case.
ATS shields, among other things, can differ in execution. For a current of 25-160 A, mounted models are used, for 160-400 A - floor models. Cables are brought in and out through a hatch in the bottom of the case. Accessories are installed inside the cabinet on a special panel.
Basic wiring rules
Of course, the power supply of a private house with your own hands must be arranged in compliance with all necessary rules. This also applies to such an operation as cabling around the premises. Directly into the house, the wiring starts through a hole in the wall. It is best to pull the cables around the premises in tubes laid in the walls during construction. In this case, if necessary, it will be easy to replace any wire that has become unusable. Each pipe must be filled with cable notmore than 40%. This will ensure easy disassembly. Also, closed wiring is sometimes mounted behind suspended or stretch ceilings, along walls sheathed with plasterboard on a frame, etc. Plastic or metal pipes are also used.
Internal power supply of a private wooden house is provided by open wiring. At the same time, the cables are pulled in special plastic channels. The height of their position on the walls is not standardized. Lighting, power and low-current wires cannot be pulled in one channel at the same time. Junction boxes are installed at branch points in both open and closed systems.
