How to make electrical wiring in a private house or apartment

The need for three-phase connection

In a single-phase network, often the only phase is overloaded due to the use of powerful units , which are becoming more and more common in modern homes. As a result, connected electrical appliances fail, creating an emergency situation that threatens a fire.

At the entrance to the house there are always three phases, which are distributed in a phase-zero set. Pairs power groups of loads of equal power. If a residential building is allocated 15 kW of power, then each group receives no more than 5 kW. If the rule is not followed, the circuit breakers will trip if the line is overloaded.

If consumers in the house require a total of more than 15 kW, a three-phase connection is needed

Equipment requiring a three-phase line connection:

• an electric heating boiler in a large house can take about 9 kW;
• water pump operating in a deep well;
• electric stove for baths, high-power saunas (from 5 kW);
• hob, oven;
• equipment for a private workshop at home, for example, milling and lathes, a circular saw, a welding machine, a jackhammer.

Such units can be found with a 220V connection, but 380V is more reliable, more powerful, and more economical . Modern devices for everyday use can be designed specifically for 380V, for example, a motor on a garage door or entrance to a yard.

Three phases are needed if there are three-phase motors on the site that are not designed to operate in single-phase regulation. Alternatively, the organization of such input is necessary when many electrical appliances are used at the same time, for example, a household has been developed, private production has been established.

They try to supply a three-phase power line to every private building, and the user can use it or not as he wishes.

Pros and cons of three-phase connection

Economical use of electricity

Low material consumption of transformers and power cables

Even load distribution

Synchronous and asynchronous current motors show high efficiency

It is possible to obtain simultaneously linear and phase voltage in one installation

Probability of reducing lamp flicker and stroboscopic effect of fluorescent lamps

In the event of an accident, one or two phases burn out, but for power supply there is the possibility of a temporary backup connection

Three phases are required if there is not enough single phase line, but in this case it is easier to request an increase in the limit

It is necessary to distribute the load evenly between phases

A new switchboard and accessories are required

The danger of electric shock increases, since the network contains not only single-phase voltage, but also linear

Disadvantages of three-phase power

Three-phase power also has several unpleasant aspects that should be considered before connecting:

1. Connection and equipment costs

If you already have a single-phase input into your house, then reconnecting to a three-phase one will require additional expenses. Such expenses include:

• Drawing up a contract . According to current legislation, drawing up an agreement for the installation of a three-phase input and a meter costs 550 rubles.
• Buying a meter and wires . The average cost of a three-phase meter included in the state register is 1,500 rubles. Also, for input you will need approximately 20 m of insulated SIP cable with a cross-section of 16 mm2, costing 1,200 rubles. It is also worth considering the need to organize wiring inside the house for a three-phase house. This indicator is difficult to calculate, since all houses are different in size.
• Additional machines . Each phase will require its own machine. You will also need to install a voltage monitoring relay so that you can always “monitor” the voltage in each phase and, in case of distortions, switch between phases.

In order for electricians to connect you to a three-phase network, you will have to stand in line and wait a couple of weeks. If you don’t want to wait, you will have to pay separately for urgency. As a result, connecting three-phase power will cost its owner a tidy sum.

1. Increased dimensions of the panel room

To connect three-phase power it is necessary to install a large switchboard. This is due to the presence of additional protective and distribution equipment. Typically, such a power cabinet or switchboard is installed outdoors so that it does not take up much space in the house.

It is worth noting that energy sales have certain requirements for distribution boards. For example, protection of the switchboard from dust and dirt should be at least IP31, and in wet rooms IP54. For some owners of summer cottages or private houses, finding a suitable place for a cabinet or installing such a structure can be a real challenge.

1. Re-wiring in the house

If initially the house had one phase, then connecting two more will require the owner to completely redesign the wiring. So initially all sockets and light bulbs were “planted” on one phase. With a three-phase connection, these sockets will need to be moved, and this means considerable repairs in the house, since you will have to trench the walls for the wiring. Naturally, this work requires additional time and money.

Requirements for connecting 380 volts

The rules for connecting the site are prescribed in the text of Federal Law No. 35 “On Electric Power Industry” dated March 26, 2003 (Articles 20 – 26), edited on December 27, 2019. The work of electric grid companies is regulated by Federal Law No. 135 “On the Protection of Competition” dated July 26, 2006.

Example specifications

Basic Rules:

• the user cannot independently connect electricity to the house; an energy supply organization is needed;
• connection is possible after fulfilling the requirements of the technical specifications;
• use cables with aluminum (not less than 16 mm²) or copper (not less than 10 mm²) conductors; armored cables are laid underground;
• with an aerial connection, the cable does not sag below the road below 6 m, above the sidewalks - below 3.5 m;
• the underground line is buried 0.7 - 1 m or lower;
• entry into the dwelling - not lower than 2.75 m from the ground;
• devices installed upstream of the electricity meter must be sealable.

In a 380V network, it is allowed to connect a three-phase meter in a private house with a maximum current strength of 50A, accuracy class - 2, last check - no more than 1 year ago. It is fixed on the DIN rail of the distribution panel, but it can be located outside the switchboard. The house must have a grounding system.

How to apply for a permit

The consumer has the right to connect to any electrical facility within 300 m from the site (power line supports, transformer substations, cable lines). The contract is concluded for a new connection, increasing power or moving the entry point.

List of project documents:

• site plan in the general layout of the development;
• connection diagram for power receivers;
• internal wiring diagram;
• PPR for connection.

The application is written at the company’s office, or submitted in your personal account through the website.

Information to be submitted with the application:

• Full name of the applicant;
• address of the connected site and the actual location of the user;
• project development period and commissioning time;
• power separation between phases;
• highest required power;
• type of load.

The company must meet deadlines for making decisions on the application. For individuals with a required power of up to 15 kW, this period is equal to 15 days, with other indicators or for a temporary connection - up to 30 days. After signing the contract, the specifications are given, which the user must exactly carry out on his site.

The owner notifies the company about the completion of preparation; in response, the electrical network checks the compliance of the specifications and the actual work in the presence of a representative of the supplier’s supply organization. A certificate of compliance is drawn up (within 3 days), the owner of the site signs the document within 5 days. This is followed by: an agreement on technological connection, an agreement on the supply of electricity. After this, 380V is supplied to the site.

Features of connecting power to a private home

Many people believe that a three-phase network in the house increases power consumption. In fact, the limit is set by the electricity supply organization and is determined by the following factors:

• supplier capabilities;
• number of consumers;
• condition of the line and equipment.

To prevent voltage surges and phase imbalance, they should be loaded evenly. The calculation of a three-phase system is approximate, since it is impossible to accurately determine which devices will be connected at a given moment. The presence of pulsed devices currently leads to increased energy consumption during their startup.

The electrical distribution panel for a three-phase connection is larger in size than for a single-phase supply. Options are possible with the installation of a small input panel, and the rest - made of plastic for each phase and for outbuildings.

Connection to the main line is carried out using underground and overhead lines. Preference is given to the latter due to the small amount of work, low connection cost and ease of repair.

Nowadays it is convenient to make an air connection using a self-supporting insulated wire (SIP). The minimum cross-section of the aluminum core is 16 mm 2, which is sufficient for a private home.

The SIP is attached to the supports and the wall of the house using anchor brackets with clamps. The connection to the main overhead line and the input cable to the electrical panel of the house is made with branch piercing clamps. The cable is taken with non-combustible insulation (VVGng) and passed through a metal pipe inserted into the wall.

Selection of materials and equipment

Input components and the meter are placed on the distribution panel, the dimensions of which are determined by the number of connection points. Metal boxes with protection from moisture are placed outside, steel and plastic cabinets are used inside.

Set of components for connection:

• corrugated tubes, self-extinguishing or non-flammable cable ducts;
• copper cable VVGng;
• three-phase meter;
• connecting switches: combs, buses, terminals;
• protective and safety fittings;
• automatic circuit breakers complete with RCDs or combined automatic circuit breakers;
• a relay that protects against voltage surges in the circuit.

A DIN rail is prepared for high-quality fastening of automatic machines and protective devices; mounting spaces for these devices are provided on the bar.

To carry out internal wiring , you need wires, boxes for changing the direction of wiring, socket boxes and for switches. You will need alabaster or plaster to fix the cables in the wall grooves, clamps, electrical tape, and adapters.

Sequence of correct installation of an electrical panel

To ensure that the electrical panel in your home is installed correctly, you should use only high-quality electrical products, as well as consumables. Only after installation is completed, operating voltage is supplied to the panel.

The correct assembly of a three-phase electrical panel has the following sequence:

1. Installation of an introductory machine. The device rating must cover the maximum power consumption. Since 3 phases will be brought into the house, the voltage between them will be 380 V, it is necessary to install a three-pole circuit breaker. To save money, it is not recommended to install 3 single-pole circuit breakers and connect them with a special strip. The input machine is installed in the upper left corner of the shield and is marked accordingly.
2. After the introductory machine, it is necessary to install an RCD. The rating of the device must correspond to the rating of the input switch. You should also pay attention to the cut-off current - the lower this indicator, the faster the RCD will turn off the network. There are differential circuit breakers that include protective functions against short circuits and shutdown the network when a leakage current occurs (RCD and standard switch). It is easier to use such a product, but its cost is quite high.
3. To the right of the RCD, at a short distance, a zero bus is mounted. Modern busbars provide a plastic dielectric between the copper strip and the shield body. This is done so that if the zero burns out and a phase gets on it, the electrical panel does not end up under life-threatening voltage.
4. Measuring instruments and voltage relays can also be placed on the strip with the input circuit breaker, RCD and zero bus. If you install a voltmeter and an ammeter in a three-phase network, then you must select products that display both linear and phase loads. And also capable of showing data on each phase separately.
5. The lower DIN rail contains automatic switches for power and lighting lines. In order not to get confused and not constantly look at the rating of the machines, lighting line products should be located at a short distance from the power switches.

Input of three phases into the building and outgoing lines

Electricity from the pole is connected to the building through the air or underground.
All conductors are connected to the electrical panel, then the electric current enters the meter and passes to the distribution unit. Here the working zero and the grounding wire are separated, they are connected to the grounding bus, which is connected to the repeated grounding branch. Formation of outgoing lines :

• additional circuits come from the input switchboard (VRS);
• an introductory switch is installed in it, all phases are connected to it;
• circuit breakers are installed for each group circuit in the home, each of them is powered from different phases;
• groups are formed according to the power of units and devices so that each phase has approximately equal value;
• three phase conductors and a neutral conductor from the grounding bus are connected to the meter contacts;
• the meter output is connected to a common circuit breaker for the entire house.

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For connection, use the triangle or star method. The first method is to connect the phases sequentially: the end of the first to the beginning of the second, the end of the second to the beginning of the third, and so on. Star - when the ends of the phases are joined at a common point and the ends of the phases of consumer windings - also in one place.

Electric meter

For any connection scheme, an electricity consumption meter is required. A 3-phase meter can be connected directly to the network (direct connection) or through a voltage transformer (semi-indirect), where the device readings are multiplied by a coefficient.

It is important to follow the connection order, where odd numbers are power and even numbers are load. The color of the wires is indicated in the description, and the diagram is located on the back cover of the device. The input and corresponding output of a 3-phase meter are indicated by the same color. The most common connection order is when the phases come first and the last wire is zero.

A 3-phase direct connection meter for a home is usually designed for a power of up to 60 kW.

Before choosing a multi-tariff model, you should coordinate the issue with the energy supply company. Modern devices with tarifficators make it possible to calculate electricity charges depending on the time of day, register and record power values ​​over time.

The temperature readings of the devices are selected as widely as possible. On average they range from -20 to +50 °C. The service life of the devices reaches 40 years with a calibration interval of 5-10 years.

The meter is connected after the input three- or four-pole circuit breaker.

Electrical panel assembly

The input switch and meter are sealed by power grid workers, so they are located at the beginning of the switchboard so as to provide this opportunity.

Step by step assembly:

• fastening of automatic devices and RCDs on the rail according to the drawn up diagram;
• connecting elements to the input switch using a comb;
• connecting phase wires with wires with lugs;
• installation and connection of the zero bus;
• checking (tightening) joints with a screwdriver;
• turning on the power, checking the operation of the machines;
• determining network parameters using a multimeter.

Before starting to operate the 380V network, make sure that all elements of the internal system (sockets, sockets, switches) are installed and connected.

Wiring of a single-phase panel

For example, the following are connected to the panel: stove (hob) 7.2 kW; oven 4.3 kW; kitchen 5.5 kW; room 3.5 kW; bathroom 3.5 kW; 3-phase motor 1.5 kW; 3-phase socket.

Let's consider this situation: you had a single-phase network and now have been given permission to install a three-phase one. In this case, all consumers need to be distributed among phases.

The most powerful device is a 7.2 kW hob (stove), which needs to be placed in the first phase. Connect the oven and room to the second one. The result is 7.8 kW. And in the third phase, connect the kitchen and bathroom. The total power will be 9 kW. Let's add more engine power, dividing it equally into each phase. The result was: in the first phase 7.8 kW; in the second phase 9.4 kW; on the third - 9.6 kW. Approximately distribute the load across the phases as evenly as possible. Let's see what kind of shield we ended up with.

• So, a three-phase panel consists of an input circuit breaker and a three-phase meter. Next, a 40 Amp circuit breaker is connected to the first phase, through which a 7.2 kW stove is powered. If you sum it up with the engine, it will be 7.8 kW.
• An oven and a microwave oven are connected to the second phase through a 25 Ampere circuit breaker. A room with a design power of 3.5 kW is connected through a second 16 Ampere circuit breaker. The total power was 8.4 kW.
• The third phase is connected to a DIF machine and a regular machine. A kitchen with a design power of 5.5 kW is connected through a regular 25 Ampere circuit breaker. A bathroom with a design power of 3.5 kW is connected via a DIF machine. The total power for the third phase is 9.6 kW.

Distribution of total motor power into three phases of 0.6 kW:

• first phase: 7.2+0.6=7.8 kW;
• second phase: 4.3+3.5+0.6=8.4 kW;
• third phase: 5.5+3.5+0.6=9.6 kW.

Connecting sockets

The peculiarity of 380V sockets is that they block from asymmetrical connection to avoid short circuit. The contacts are placed at an angle, they are different in size, with guide elements.

Stationary 380V sockets are produced in the following types:

• 2P+PE has two power (phase) terminals and a grounding terminal;
• 3P+PE or 3P+N is characterized by three phase terminals and one for grounding connection;
• 3P+PE+N - there are places for connecting three phases, one for zero, one more for grounding.

The sockets are interlocked to prevent switching off under load. The current strength (25, 63, 125A) for which these sockets are made is significant, and the products do not have an arc-extinguishing effect. Removing plugs under such a load is dangerous in terms of burns or burnt out sockets. The lock can be of an electronic or mechanical type.

Sockets are connected to the power cable in series, parallel or in a mixed way.

What is a three-phase network?

Before putting into operation, any house or apartment is connected to the local power grid. Such a network can be single-phase or three-phase. With a single-phase connection, two wires are supplied to the house, a phase and a zero, between which the voltage is 220 V. A three-phase network is characterized by the presence of four wires: three phases and a zero. Between each phase and zero the voltage is 220 V, and between the phases themselves 380 V (as shown in the image).

To account for electricity in such a network, a three-phase meter is required, which is installed by the local distribution zone. A typical example of such a meter is INCOTEX Mercury 231 AM-01, designed for metering active electricity.

Electrician's recommendations

For hidden wiring, built-in electrical panels are chosen, and exposed wires are connected in overhead distribution panels. The shield body is placed so that it can be easily reached.

Electricians advise observing the following conditions:

• horizontal sections of wires from the panel to the sockets are made at a height of 2.5 m from the floor;
• wiring in the walls is placed vertically or horizontally; it is prohibited to install it along an oblique line;
• connect the wires with adapters in installation boxes;
• the underground connection to the power pole is made with a single piece of wire without connections;
• Do not connect the switch to the neutral wire;
• When laying on wooden walls, insulating hoses with asbestos linings are used.

The distribution housing is selected according to the type of room, taking into account the characteristics of the microclimate - in aggressive environments, boxes with maximum protection from direct water jets and dust are used.

Power consumption

It is important for the home owner to know how much energy is consumed. This is easy to calculate for all electrical appliances. Adding up all the powers and dividing the result by 1000, we get the total consumption, for example 10 kW. For household electrical appliances, one phase is sufficient. However, current consumption increases significantly in a private home where there is powerful equipment. One device can have 4-5 kW.

It is important to plan the power consumption of a three-phase network at the design stage in order to ensure symmetry in voltages and currents.

A four-wire wire with three phases and a neutral enters the house. The voltage of the electrical network is 380/220 V. 220 V electrical appliances are connected between the phases and the neutral wire. In addition, there may be a three-phase load.

The power calculation of a three-phase network is carried out in parts. First, it is advisable to calculate purely three-phase loads, for example a 15 kW electric boiler and a 3 kW asynchronous electric motor. The total power will be P = 15 + 3 = 18 kW. In this case, current I = Px1000/(√3xUxcosϕ) flows in the phase wire. For household electrical networks cosϕ = 0.95. Substituting numerical values ​​into the formula, we obtain the current value I = 28.79 A.

Now you need to define single-phase loads. Let them be PA = 1.9 kW, PB = 1.8 kW, PC = 2.2 kW for the phases. The mixed load is determined by summation and is 23.9 kW. The maximum current will be I = 10.53 A (phase C). Adding it to the current from the three-phase load, we get IC = 39.32 A. The currents in the remaining phases will be IB = 37.4 kW, IA = 37.88 A.

When calculating the power of a three-phase network, it is convenient to use power tables taking into account the type of connection.

Using them it is convenient to select circuit breakers and determine wiring cross-sections.

Electrical grounding diagram

There are many examples of how grounding works. Let's assume that a breakdown occurs in the washing machine motor, due to which some of the electric current is supplied to the outer frame of the device. If there is no grounding, the electrical charge will remain on the shell of the washing machine and can pose a danger to humans; when a person touches the machine, it becomes an excellent outlet for electricity.

In this case, the ground wire can drain the current charge. The neutral conductor can also act as a grounding and is often used at power plants, but at home you should never try to make a grounding wire out of the neutral wire, since if the neutral wire breaks, all the housings of the devices grounded with its help will immediately be energized. 220 V. In most cases, in ordinary apartments a single-phase circuit is implemented. It is quite easy to distinguish a single-phase circuit from a three-phase one. If there are 2 or 3 wires in the incoming wire, then the circuit is single-phase, if there are 4 or 5 wires, then the circuit is three-phase.

To save money, current is often supplied to residential buildings through a three-phase network, but it enters the apartment through a single-phase network. The circuit is split through an input-distribution device, where a five-core cable is connected, and a three-core wire extends from it. This must be taken into account when calculating the cost of an electrical project.

When considering the method of splitting a three-phase circuit, a natural question may arise: where do the two remaining wires disappear? In reality, everything is very simple: they are used to feed other apartments within the same building. One cable can power a large number of buildings, the number of which is limited only by the capabilities of the wire itself.

Three-phase and single-phase wiring in the apartment

Many, even the most important concepts in the field of building electrification can remain mysteries for ordinary people who do not encounter them in everyday life.
Single-phase and three-phase wiring diagrams in an apartment, grounding - all these are fundamental aspects, without knowledge of which it is impossible to prepare a single electrical project for a wooden house or apartment. If we don’t talk about technical aspects that are not very necessary for the homeowner, three-phase wiring is a separate type of electricity transmission that involves transmitting current through three wires and returning one at a time.

An example of a three-phase wiring project in an apartment

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For clarity, it is worth noting that any wiring consists of two cables, through one the current flows to the electrical consumer, and through the second it returns. If such a circuit is broken, the current will stop flowing in both directions. This description applies to a single-phase network.

The wire through which the current flows to the consumer is usually called the phase wire, and the second through which the current returns is called the neutral wire. As the name implies, a three-phase circuit includes three phase wires and one neutral wire.