Not so long ago, owners of private houses connected to the power lines themselves. In controlling organizations it was only necessary to submit an application, as well as install a counter. Today, the situation has changed radically. To connect to the mains, you need to provide a project with a description of the power supply methods for all appliances installed in the house (boiler, speakers, etc.). That is, the package of documents necessary for obtaining permission must necessarily include a single-line diagram of the system that ensures their operation. We will talk about how to compile it, and how to arrange the power supply of a private house competently, and we will talk further.
Electrification project of a country house. Three phase or single phase network?
Of course, before you draw any schemes and go to make out the connection, you will need to determine the type of power supply, its source, etc.
In private houses, as in urban apartments, a three-phase or single-phase network can be used. Both varieties have their own disadvantages and advantages. Initially, any industrial network has three phases. In high-rise buildings, they are usually distributed into apartments. Moreover, due to the difference in the number of electrical appliances used, the load on the phase wires is often different. As a result, sometimes the neutral wire 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 the phase distribution. However, with improper use of the network, various kinds of problems - up to the failure of electrical appliances - may occur in this case too. To prevent such troubles, you should use a stabilizer, which is very expensive. In addition, it will be necessary to purchase equipment and elements designed specifically for the three-phase line. Which also will fly a pretty penny. Therefore, a three-phase power supply circuit of a private house should be used when there really is a need for it. That is, if it is supposed 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 a comfortable stay in any building is the constant availability of current in the network. However, unfortunately, when the power supply of a private house is made from a common power line, problems often arise due to interruptions in its supply. A good way out of this situation may be the additional use of autonomous power supplies. These include:
- UPS In the event of a power outage, this device begins to function 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 sufficient power, the generator can provide electricity to even a very large house for a long time.
How to get permission to connect
So, with the number of phases, a variety of additional power sources, etc., you have decided. What next? In what order is a private house connected to the power line? Power supply of suburban buildings is controlled by the network supply company in whose area of responsibility they are located. It will also be necessary to turn to its specialists by collecting the necessary package of documents. Their list should be known in advance.
After receiving the documents, the network company will prepare technical conditions for the power supply of a private house. Most likely, they will have to be coordinated with various related organizations. Next is a contract. After the network is mounted, a representative of the network organization comes to the place and performs its check for compliance with the requirements set forth in the technical conditions. Inspection is carried out with the participation of all interested parties. Then Rostekhnadzor gives permission to operate the network.
Single line circuit
First, let's see what, in fact, is such a drawing. A single-line circuit is, in fact, the same principle, but made in a simpler form. That is, all the mains, both single-phase and three-phase, are indicated on it by one line. Detailed detailing in such schemes is absent. 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 performed.
There are some rules for drawing up such schemes, which we will talk about later. They are not particularly difficult, but you need to know about them. Otherwise, the project will not be accepted.
Purpose and main requirements
The single-line power supply scheme of a private house is an important document by which all installation work is performed. It must be composed in such a way that:
- The safety of using electrical equipment was ensured in terms of electric shock.
- It was guaranteed that there was no risk of a fire in the house as a result of a short circuit, melting of wires, etc.
- During the operation of the building, the people living in it had the opportunity to easily use all the modern, powerful electrical appliances they needed.
These are the basic requirements for this document.
What types exist
Such a simplified power supply scheme for 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 existing system or for some reason there is a need to provide information to the energy distribution company. Before drawing up the circuit, 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 with a complete replacement of the old wiring. In this case, all the necessary calculations are made (loads, cable cross-sections, etc.), as well as the selection of suitable equipment (protection devices, etc.).
Compilation rules (conventions)
Of course, a linear diagram of the power supply of a private house should be drawn in compliance with all the required standards. The latter are determined by GOST 2.702-75 and have been in force since 1988. They indicate exactly which conventions should be used to represent certain elements of the electrical wiring of the house on the diagram. To display a three-phase connection, the following methods can be used:
- a crossed-out line with the number “3” affixed next to the output or input,
- a straight line crossed out by three oblique lines.
For the designation of devices, contactors, starters, switchboards, sockets, etc., exactly the same symbols are used as in any other wiring diagrams (GOST 2.709).
What should be present
A single-line power supply scheme of a private house must necessarily include the following elements:
- connection point to the electric highway;
- brand of input device and rated current at the connection point;
- cable brand, its cross section and length (accurate to a meter);
- voltage loss values in the lines;
- rated and actual power of ASU, their cosφ and rated current;
- brand of protective devices and their rated current;
- design loads;
- the boundary of the balance sheet;
- a kind of cabinet ABP with an indication of the mode of its operation;
- used devices of commercial accounting and control.
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 simply prints to the printer. For example, the program “1, 2, 3 circuit” is designed to create a single-line circuit of the electrical panel, 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 you to:
- in accordance with the requirements to choose the body of the electrical panel;
- equip it with modular devices;
- determine the hierarchy of connection of the latter;
- form a ready-made diagram.
The program database contains current certified articles of the necessary equipment.
Load calculation
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 cross-section of the cables. How this is done, and we will talk further.
A residential private house, the power of which 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, add their power and divide by voltage. The result is the required amperage. Knowing it, you can determine from the special tables whether the network is overloaded and what cable is needed for wiring. When making calculations, it is necessary to take into account the power of not only existing electrical appliances, but also those planned for purchase in the future.
For some very powerful household appliances, for example, a washing machine, boiler or electric stove, it is best to stretch a separate cable. Often a separate highway is also carried out to office equipment. In the case of the use of some professional equipment in the garage or commercial building, as already mentioned, three-phase power supply of a private house is used.
How to choose a cable for the network
For a single-phase connection, you need wires with three wires, for a three-phase connection, respectively, with five. When developing a project, it is very important to choose a cable of suitable section (guided by the PUE). This indicator can be found in special tables, depending on the current strength. The required conductor diameter is pre-calculated. This is done by the formula d = k × I + 0.005. Here k is a constant coefficient for the metal of the conductor. For example, for copper it is equal to 0.034. The letter I denotes the current strength.
They sell wires using a cross-section rather than a diameter as a measurement system. Therefore, further it will be necessary to determine it. For this, there is a formula S = 0.785 × d2.
A preliminary calculation can be done based on the fact that per square millimeter of copper wire can be 10 A, aluminum - 7 A. In practice, outlets usually use a wire of 2.5 mm 2 , and for lighting 1.5 mm 2 .
Input device selection
The power supply of a private house is connected through the so-called VU. They are metal enclosures in which devices are designed to control the building’s electricity network. Models that perform the distribution function including are called ASUs. Install input devices either on the pole of the power line, or next to the building.
When choosing an ASU in a private house, the power supply of which should be safe and uninterrupted, you need to consider:
- The value of the line voltage. To country houses, usually 220 V.
- Current frequency. 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 neutral and protective wires extend in one conductor. Their separation is carried out inside the WU.
- 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 according to special formulas.
- Installed capacity.
TN-C systems typically use a single-pole input circuit breaker at 220 V, and at three-pole at 380 V. In the first case, the power calculation of the input device is calculated by the formula I p = P p / U f × cos f (where U f is the phase voltage, Pp is the rated power, Cos f is the active / reactive power). The power of the input device for the 380 V network is found by the formula Ip = Pp / (√3xUhx cos ) (where Uh is the network voltage).
The rated current must be 10% higher than the rated current. Therefore, the final result is determined by the formula I TR = I p × 1,1.
Shields ABP
The power supply system of a private house usually includes this element. The ABP shields 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 a stationary network and to a generator. There are such types of shields:
- Priority first entry. In this case, when the voltage disappears at the main input, it automatically switches to the backup. In the event of a current, the reverse process occurs.
- No priority. Back to the main input when voltage appears on it, such devices do not automatically switch. This procedure in this case is performed manually.
- With partitioning. In such devices, power is supplied through a system of switches mounted on the inputs. In the event of a power failure, a third switch starts to function on one of them, supplying voltage to de-energized consumers from the working input.
- With DGU. In this case, when the voltage drops on both inputs, the generator starts. When restoring the main power, the system returns to its original state. The power supply of a private house using this option will be uninterrupted in any case.
The ABP shields differ, among other things, by execution. For currents of 25-160 A, mounted models are used, for 160-400 A - floor mounted. Cables enter and exit through the hatch at the bottom of the chassis. Accessories are installed inside the cabinet on a special panel.
Basic rules for wiring
Of course, the power supply of a private house with their own hands should be arranged in compliance with all necessary rules. This also applies to operations such as cabling in rooms. Directly into the house, wiring is started through a hole in the wall. Indoors, cables are best pulled in pipes laid in the walls during construction. In this case, if necessary, it will be possible to easily replace any wire that has become unusable. Each pipe should be filled with a cable no more than 40%. This will ensure easy disassembly. Also, closed wiring is sometimes mounted behind suspended or suspended ceilings, along walls lined with plasterboard on the frame, etc. Plastic or metal pipes are also used.
Internal power supply of a private house made of wood is provided by wiring open wiring. Cables are pulled in special channels made of plastic. The height of their position on the walls is not standardized. In one channel, it is impossible to extend simultaneously lighting, power and low-current wires. Junction boxes are installed at branch locations in both open and closed systems.