As you know, repairs are akin to a small-scale natural disaster, and one of its integral components is the electrification of a residential or office space. We remember how important electricity plays a role in the home when it suddenly disappears due to an accident. Providing an apartment or private house with electricity, as a rule, includes two basic components, this is the installation of electrical wiring and the assembly of the electrical panel.
Each of these components provides for the sequential implementation of a number of steps, which at first glance are quite simple, however, as practice shows, in the overwhelming majority of cases requiring the participation of a professional electrician. If the owner of the premises intends to independently solve the problem of supplying electricity to the house or apartment, it is necessary, at least, to carefully study the materiel, that is, prepare theoretically before assembling the electrical panel with your own hands.
The electrical panel is the heart of the home electrical system
We will not be mistaken if we say that the main function of an electrical panel installed at home, office, cafe or any other room is to distribute electricity to consumers and ensure safety when using electrical appliances. Each owner of a residential or office space at some point is forced to deal with a problem: how to assemble an electrical panel. Long-term uninterrupted operation of a huge amount of household appliances, which any house or office is filled with today, to a large extent depends on how correctly the electrical panel is assembled.
The shield itself is a plastic or metal box in which components (or modules) are placed, each of which performs a specific function. There are so-called internal switchboards, that is, recessed into the wall, and external ones, located on the wall.
In a private house, an electrical switchboard is often installed in the open air, in this case, a waterproof design of the device will be required (degree of protection IP65). Given the fact that it is unlikely that the electrical panel will change annually or even every five years (as a rule, the device serves much more), it will be advisable when choosing a device to give preference to a more expensive but high-quality shield of a well-known brand with a stock of seats.
Where to start?
Each experienced electrician will confirm that it is much easier to get started on the installation of the electrical panel and wiring, having before your eyes a floor plan indicating the intended location of household appliances, lighting fixtures, as well as sockets and junction boxes. Having decided on the number and power of consumers, it is necessary to draw up a diagram of the switchboard itself. A single line diagram might look like this:
In this diagram, all consumers are divided into 20 groups, for each of which are indicated:
- wire brand and conductor cross-section, mm²;
- power;
- consumed current;
- type of circuit breaker with indication of rated current.
For the uninitiated, such a scheme looks quite complicated, so you can use a simplified schematic representation of the location of the electrical panel components.
For greater clarity, the electrical panel diagram can be depicted as follows:
Or even like this:
- 1 - introductory AB;
- 2 - counter;
- 3 - zero bus;
- 4 - grounding bus;
- 5–10 - AV consumers.
With such a circuit in hand, it is much easier to figure out how to properly assemble an electrical panel.
How to properly form consumer groups
When distributing electricity consumers into groups, certain rules should be adhered to:
- powerful consumers (2 kW or more), which, as a rule, include a hob, an oven, a water heater, a washing machine, and so on, should be powered by a separate switch. In this case, the cable must go from the panel to the consumer, bypassing the junction boxes;
- two-kilowatt consumers are connected with a 2.5 mm² copper cable and a 16 A circuit breaker. If you follow the tabular data, then for a 2 kW device, 1.5 mm² wires are enough, as well as a 10 A machine, but to create some margin, the components of the following are usually mounted level;
- in some cases (if the consumer's power exceeds 2 kW), a wire with a cross section of 4 mm² with AB 25A or a wire of 6 mm² with AB 32 A may be required - such components are sometimes used when connecting a hob, oven or instantaneous water heater;
- for each room, a separate outlet line should be made, which will branch out from the distribution box to the required number of outlets;
- the same applies to the lighting line - each of them is connected, as a rule, with a 10 A automatic machine and a 1.5 mm² wire.
It is this approach to the distribution of consumer groups that can ensure the smooth and safe operation of home and office electrical appliances. It is highly undesirable to use components and materials of dubious origin, even if they are much cheaper than "branded" ones: with a high degree of probability, such parts will have to be changed in the near future.
The socket line, as a rule, is equipped with a 16 A circuit breaker.
Electrical panel components
The assembly of the electrical panel provides for the presence of mandatory components, which include circuit breakers, residual current devices, RCDs, electricity meters, buses, as well as additional and auxiliary components that add convenience when using the panel: voltage control relays, light indicators, digital voltmeters, contactors, etc. etc.
Among the most respected by specialists manufacturers of components used in the installation of an electrical panel are ABB, Legrand, Shcneider Electric. The prices for the devices of these brands are about the same. Chinese appliances are much cheaper, but practicing electricians claim that once using Chinese appliances when completing an order, you can lose your reputation for a long time, therefore, such components are used only at the request of a customer who cannot afford branded components.
Everything is ready for installation
So, the diagram is drawn up and comprehended, the components are prepared - nothing prevents you from starting the assembly of the switchboard. First of all, the location of the flap is chosen, on which the device is attached, as a rule, with self-tapping screws or clamps. The body of the electrical panel is located, as a rule, not far from the entrance to the house or apartment - in the vestibule or hallway. If the owner has expressed a desire to hide the shield in the wall, and the wall turns out to be concrete, you can use a false wall or a plasterboard ledge: the area of the room may decrease somewhat.
When choosing a place on the wall to install the electrical panel, it should be borne in mind that the distance from the device to the nearest doorway should be at least 15 cm, the distance to the floor should be 1.5–1.7 m. : it is absolutely unacceptable to place the device inside cabinets or other furniture. The device should be located away from gas pipes and flammable materials.
So that the electrical panel does not turn out to be too large or small, you can pre-determine its size, knowing the dimensions of the components that will be located in it. For example, the width of a standard single-pole circuit breaker is 17.5 mm, a double-pole circuit breaker is 35 mm, and a three-pole circuit breaker is 52.5 mm. The rest of the components have the following dimensions:
The modules are located on the so-called DIN rail - a special metal plate 35 mm wide. The socket is not included in the number of mandatory elements, but it can be useful when carrying out repair work. If, when summing up the number of components, it turned out that a shield for 20 modules is needed, then it would be reasonable to install an electrical panel for 24 or even 32 modules - who can know how many household electrical appliances will be added to the house in a year, two or five?
We put cables into the electrical panel
The presence of a special cable gland with a removable cover can save you from problems with cable routing into the shield. On high-quality panels, such an input, as a rule, is provided, it is better not to consider low-quality ones at all. If the switchboard is installed outside, there are usually no problems with cable routing. If the flap is hidden in a niche, there may be nuances: getting to the inlet in this case is quite difficult, so the electrician needs to be patient and enduring.
The design of the cable entry of the electrical panel provides, as a rule, perforated holes, which are brought to the required size by simply removing unnecessary jumpers. Cables are led into the shield through a corrugated pipe, the standard size of which is 16 or 20 mm, respectively, and the holes should be made of this size.
Often an electrician is prevented from working by the mobility of the wires inside the corrugated tube. To fix the wires and make them stationary, some use alabaster, which is fed to the inlet from the side of the strobe. Let's make a reservation right away that this method of fixation is not convenient and aesthetic enough. It is much more efficient to secure the wires using special removable plugs or gland plates.
To avoid confusion with the wires in the future, you should immediately label them. The lead-in cable is usually fed in in the upper left corner - where the automatic input machine is usually installed.
We cut cables and assemble modules
Every electrician will confirm that it is easier and more enjoyable to work with a tool specially designed for a particular operation. You can cut the cables inside the shield with an ordinary construction knife, but if you do this with a special knife with a heel, everything turns out faster and better.
After cutting the cables, you should re-mark the wires, since there will be a lot of them and if you get tangled in them, it will take a lot of time to put things in order. When supplying cables to the shield, leave such a length that will be equal to the double height of the shield, that is, pass the cable through the entire shield, and then measure the same amount. Such a measure is not wasteful: the wires inside the shield do not go in a straight line, but along an intricate curved line, and let it be better to have a little extra wire than not enough.
There are no strict rules for the location of modules in the switchboard, however, electricians, as a rule, use one of two installation schemes - linear or group. In the first case, all the elements are arranged one after the other in the order shown in the single-line diagram: input machine, RCD, difavtomats, consumer circuit breakers. Among the advantages of this location option are ease of implementation, the disadvantage is that it is difficult to find the "culprit" of an emergency.
If a group layout of modules is implemented in the panel, the components alternate according to consumer groups: AV input, RCD, a group of switches tied to this RCD. Next, the next RCD and the corresponding group of circuit breakers are installed. Such a circuit is somewhat more difficult to assemble, but the problem line is immediately visible by the triggered RCD.
Build rules
There are certain rules that should be followed when assembling an electrical panel:
- all wires inside the shield must be of the same cross-section as the lead-in wire;
- any module must have an entrance at the top, an exit at the bottom;
- if the installation is carried out using a stranded wire PV3, it is imperative to use NSHVI lugs.
The sequence of steps for an electrician performing an assembly might look like this:
The final stage
Installation of the shield in its place is carried out at the end of all dirty repair work. The shield body is mounted in a niche, din-rails with assembled modular equipment are fastened with self-tapping screws. The busbars of the working (N) and protective (PE) zero are fixed. Phase and neutral wires are arranged in separate bundles and laid on opposite sides of the shield. The force with which the connections are clamped is 0.8 Nm.
Before starting commissioning work, make sure that all sockets, junction boxes, switches are assembled. All consumer groups should be signed on the external panel of the electrical panel. After about a month of work, all connections of the shield should be tightened.
Related Videos
Connecting circuit breakers in a switchboard requires a lot of knowledge. First, you need to correctly design the wiring, then choose a location, make diagrams, choose a case and accessories. After all these procedures, you need to install the equipment, and connect the shield to the cable.
Incorrect connection of the machines can lead to big wiring problems, so it is better to contact an experienced electrician in this matter.
In this article, we will talk about the process of correctly connecting the machines to the panel, laying cables and the correct layout of all parts. It is impossible to imagine a modern house without electricity, this issue should be in the forefront.
Electric panel for counter and vending machines - choice of installation location
Let's start with the simplest part - where to place the switchboard in the apartment? It is most convenient to place it near the front door in the hallway. In this case, you do not have to pull the power cable far from the platform. The most optimal height option is at the eye level of an adult. And it is convenient to take meter readings, and turn off the machines if necessary.
For supporters to cram everything under the ceiling, “for greater safety, as they say they used to hang meters before,” let's say the following. Old electricity meters with plug fuses were simply mounted on the wall without drawers, and therefore hung under the ceiling.
The modern electrical panel has a sturdy housing and is lockable so that children will not fit in unless you drop the key in a prominent place.
When choosing a place for mounting the shield in a private house or cottage, you need to consider where and how the cable is installed or will be started from the overhead line or underground supply line. Data on external networks can be obtained from the local power supply company.
Buy ready-made or assemble an electrical panel with your own hands
As the old song says, "how much progress has come," that you can buy a ready-made shield with a full filling or assemble a ready-made one. If your electrician offers such a “proprietary” build design, then don't be alarmed. Shields are assembled by enterprises and electrical installation firms, including on order or for standard projects of apartment wiring.
The main point that needs to be clarified is whether your master has worked with ready-made shields before or this is the first experience. If he has installed a dozen or two of such assemblies and knows their features, then feel free to agree. But if you are a guinea pig for the first experiment, refuse. Better to collect it himself, with pens, in the old fashioned way.
Connection diagram of machines in the dashboard
The scheme of the dashboard in the apartment is one of the main points, but before dealing with it, let's see what elements are included in the design. So that you understand the designations and composition of the wiring diagram.
- Usually, when installing the shield, use:
- Introductory machine.
It is put to protect the entire wiring circuit. The cores of the main incoming cable are connected to the terminals of the input machine. For convenient work with the electrical panel, a switch is often installed in front of the input machine.
It allows you to de-energize the entire assembly for replacement of elements, safe prevention and completely cuts off the power supply to an apartment or house. In this case, the power cable is connected to the switch.
- Electricity meter.
It is installed after the introductory machine and counts the power consumption in the house or apartment. Sometimes the meter stands separately, up to the dashboard, along with an automatic shutdown. For example, at the site of an apartment building.
- Residual current device - designed to protect against electric shock and prevent fires.
The RCD in the circuit can be as one installed after the meter, for example, in a one-room apartment with a small load. Or they put several RCDs on separate lines with high consumption (on an electric stove, washing machine, air conditioner).
- Linear machines.
Needed for separate lines for different rooms, household appliances and lighting. Break the circuit if an overcurrent or short circuit is detected, protect the wiring and connected equipment from damage. The operation of the machine can prevent fire due to heating and ignition of the wire.
- Diffautomat of protection.
It can be installed instead of a pair of automatic machine + RCD on separate power lines of electrical appliances.
- DIN rail - a mounting element for installing equipment.
Fastened to the rear wall of the electrical panel housing. Depending on the size of the cabinet, the number of DIN rails and the possible number of installed modules may be different. In order not to be mistaken with the purchase of the shield case according to the number of modules, it is necessary to draw up a wiring diagram.
- Connecting busbars.
They are needed to disconnect the electrical panel and connect the working zeros and ground wires. In the shield, both zero terminal strips and grounding ones are used.
- Distribution busbars.
Installed for the "bundle" of linear automata, RCDs, difavtomats. The combs have reliable insulation and allow you to quickly and safely connect a number of machines through the input terminal block. They can be used for both current conductor and working zero.
What are circuit breakers
These are specially designed devices, the main task of which is to protect the wiring from reflow. In general, machines will not save you from electric shock and will not protect equipment. They are designed to prevent overheating.
- The technique of their work is based on opening the electrical circuit in several cases:
- short circuit;
- excess of the current flowing through the conductor for this not intended.
As a rule, the machine is installed at the input, that is, it protects the following section of the chain. Since different wiring is used for breeding to different types of devices, it means that protection devices must be able to operate at different currents.
At first glance it may seem that it is enough to install just the most powerful machine and there are no problems. However, it is not. A high current, which has not been triggered by the protection device, can overheat the wiring and, as a result, cause a fire.
What the machine consists of
- A typical automaton consists of the following elements:
- Cocking handle. With the help of it, you can turn on the machine after it is triggered, or turn it off to de-energize the circuit.
- Activation mechanism.
- Contacts. Provides connection and opening of the circuit.
- Terminals. They are connected to the protected network.
- Conditionally triggered mechanism. For example, a bimetallic heat plate. In many models, an adjusting screw may be present to adjust the nominal current value.
- Arc-extinguishing mechanism. Present at each pole of the device. It is a small chamber in which copper-plated plates are placed. On them, the arc is extinguished and comes to naught.
Depending on the manufacturer, model and purpose, the machines can be equipped with additional mechanisms and devices.
The device of the shutdown mechanism
The machines have an element that breaks the electrical circuit at critical current values.
- Their principle of operation can be based on different technologies:
- Electromagnetic devices. They are characterized by a high speed of reaction to a short circuit. Under the action of currents of an unacceptable value, a coil with a core is triggered, which, in turn, turns off the circuit.
- Thermal. The main element of such a mechanism is a bimetallic plate, which begins to deform under the load of high currents. Bending, exerts a physical effect on the element that breaks the chain.
An electric kettle works in approximately the same way, which is able to turn itself off when the water boils in it. There are also semiconductor circuit breakers. But they are rarely used in household networks.
Time-current characteristics of circuit breakers
Devices differ in the nature of operation for an unnecessarily high current value. There are 3 most popular types of machines - B, C, D.
- Each letter means the sensitivity coefficient of the device:
- B (3 to 5 xln);
- C (5 to 10 xln);
- D (from 10 to 20 xln).
What does it mean? It's very simple - to understand the range at which the machine is capable of triggering, you need to multiply the figure next to the letter by the xln value.
- So for the B16 machine:
- 16 * 3 = 48A;
- 16 * 5 = 80A.
- Take, for example, three machines with the same rated current 16A, but different time-current characteristics:
- the machine marked B16 will shut down in the range 48 ... 80A;
- marked C16 will shut down in the range 80 ... 160A;
- and marked D16 will shut down in the 160… 320A range.
The most common type of machine is C, it is used in almost every home.
The machines with the D marking are used mainly in places with consumers that have high starting currents, for example, electric motors.
Type B is the most sensitive, rarely used, mainly for the protection of electronic equipment. And it is correspondingly more expensive.
At a current of 100 A, the B16 machine will turn off almost instantly, while the C16 will not turn off immediately, but after a few seconds from thermal protection (after its bimetallic plate heats up).
Symbols
Different types of machines are marked in their own way for quick identification and selection of the one needed for a particular circuit or its section. As a rule, all manufacturers adhere to one mechanism, which allows unifying products for many industries and regions.
- Let's take a closer look at the signs and numbers printed on the machine:
- Brand. Usually, the manufacturer's logo is placed on the top of the machine. Almost all of them are stylized in a certain way and have their own corporate color, so it will not be difficult to choose a product for your favorite company.
- Indicator window. Shows the current status of contacts. If there is a malfunction in the machine, then it can be used to determine whether there is voltage in the network.
- Machine type. As already described above, means the tripping characteristic at currents significantly higher than the rated one. C is used more often in everyday life and B is used a little less often. The differences between the types of electric machines B and C are not so significant;
- Rated current. Shows the value of the current that can withstand continuous load. Rated voltage. Very often this indicator has two meanings, written with a slash. The first is for a single-phase network, the second is for a three-phase one. As a rule, in Russia the voltage is 220 V.
- Cut-off current limit. It means the maximum permissible short-circuit current at which the machine will shut down without failure. Current limiting class. Expressed in one digit or absent at all
- Scheme. On the machine, you can even find a connection diagram for contacts with their designations. It is located almost always in the upper right part. Thus, by looking at the front of the machine, you can immediately establish what type of current it is intended for and what it is capable of.
What type of machine to choose
When choosing a protective device, it is the rated current that is considered one of the main characteristics. To do this, you need to determine what current strength is required by the totality of all consumer devices in the house.
And since electricity flows through the wires, the current strength required for heating depends on its cross section. The presence of poles also plays an important role.
- The most common practice is:
- One pole. Chains with lighting devices and sockets to which simple devices will be connected.
- Two poles. It is used to protect the wiring to electric stoves, washing machines, heating devices, water heaters. It can also be installed as a protection between the shield and the room.
- Three poles. It is mainly used in three-phase circuits. This is true for industrial or near-industrial premises. Small workshops, production facilities and the like.
The tactic of installing machines comes from more to less. That is, it is first mounted, for example, two-pole, then single-pole. Next come devices with power decreasing at each step.
The first thing to start with is the correct connection of the machine in principle. As you know, the circuit breaker has two contacts for connecting movable and fixed.
Which pins do you need to connect power to the top or bottom? To date, there have been a lot of controversies on this matter. On any electrotechnical forum, there are a lot of questions and opinions on this matter.
Let's turn to the regulatory documents for advice. What does the PUE say about this? 7th edition PUE clause 3.1.6. said:
3.1.6. Circuit breakers and plug type fuses must be connected to the network so that when the fuse (circuit breaker) plug is unscrewed, the screw fuse (circuit breaker) sleeve remains de-energized. With one-sided power supply, the connection of the supply conductor (cable or wire) to the protection device should be carried out, as a rule, to fixed contacts.
As you can see in the rules, it is said that the supply wire when connecting the machines in the shield should be connected, as a rule, to fixed contacts. This also applies to all RCDs, difavtomats and other protection devices. From this whole clipping, the expression "as a rule" is not clear. That is, it seems, as it should, but in some cases there may be an exception.
To understand where the movable and fixed contact is located, you need to imagine the internal structure of the circuit breaker. Let's look at the example of a single-pole machine where the fixed contact is located.
Before us is an automatic machine of the BA47-29 series from iek. From the photo it is clear that its fixed contact is the upper terminal, and the moving contact is the lower terminal. If we consider the electrical designations on the switch itself, then it is also clear here that the fixed contact is on top.
Circuit breakers from other manufacturers have similar markings on the case. Take, for example, an automatic machine from Schneider Electric Easy9, it also has a fixed contact on top. For Schneider Electric RCDs, everything is similar on top there are fixed contacts, and on the bottom there are movable ones.
Another example is protective devices from Hager. On the case of the hager circuit breakers and RCDs, you can also see the designations, from which it is clear that the fixed contacts are on top.
Let's see if it matters from the technical point of view how to connect the machine from above or below.
The circuit breaker protects the line against overloads and short circuits. When overcurrents appear, the thermal and electromagnetic release located inside the housing react.
From which side the power will be connected from the top or from the bottom to trip the releases, there is absolutely no difference. That is, we can say with confidence that the operation of the machine is not affected by which contact will be supplied with power.
In truth, I must say that manufacturers of modern "branded" modular devices, such as ABB, Hager and others, allow the power supply to be connected to the lower terminals. For this, the machines have special clamps designed for comb tires.
Why, in the PUE, it is advised to connect to fixed contacts (upper)? This rule is approved for general purposes. Any educated electrician knows that when performing work, it is necessary to remove voltage from the equipment on which he will be working.
"Climbing" into the switchboard, a person intuitively assumes the presence of a phase on top of the machines. Having disconnected AB in the shield, he knows that there is no voltage at the lower terminals and everything that leaves them.
Now let's imagine that the connection of the machines in the switchboard was performed by an electrician, Uncle Vasya, who connected the phase to the lower contacts of AB.
Some time has passed (week, month, year) and you need to replace one of the machines (or add a new one). Uncle Petya, an electrician, comes in, turns off the necessary machines and confidently climbs under tension with his bare hands.
In the recent Soviet past, all machines had a fixed contact at the top (for example, AP-50). Now, by the design of modular AB, you cannot tell where is the movable, and where is the fixed contact. At AB, which we considered above, the fixed contact was located on top. And where are the guarantees that the fixed contact of the Chinese machines will be located on top.
Therefore, in the rules of the PUE, the connection of the supply conductor to fixed contacts implies only connection to the upper terminals for the purpose of general order and aesthetics. I myself am a supporter of connecting power to the top contacts of the circuit breaker.
For those who disagree with me, the question is about filling, why on electrical circuits the power to the machines is connected to fixed contacts.
If we take, for example, a conventional RB-type switch, which is installed at every industrial facility, then it will never be connected upside down. Connecting power to switching devices of this kind is supposed only to the top contacts. I turned off the switch, and you know that the lower contacts are without voltage.
Connection of circuit breakers
After the vending machine is selected, it must be connected. Connecting circuit breakers is not a difficult task and everyone can do it.
Automatic switches are installed in the box for electrical machines. To securely fix the machine in the electrical panel, it is placed on a special din rail. The wires in the terminal clamps of the machine are fixed with bolted contacts.
During installation in electrical panels and connecting supply or outgoing lines, it is necessary to tighten the bolt contacts carefully, without excessive force.
The tightening of the contacts should not be accompanied by deformation of the machine case, as this can lead to a violation of the positions of the current-carrying parts inside the machine case, which can cause excessive overheating of the machine and its failure even with minor loads.
When connecting the machine, it is necessary to observe the generally accepted rule: the input (power) is connected from the top of the machine, and the output (load) is connected from the bottom.
In the future, when it becomes necessary to replace or connect additional wires to the work machine, you will always know to which contact the load and power are connected.
Before connecting the cores of the cable to the terminals of the machine, the external insulation of about 10-15 cm is removed from it, after which the cable becomes more flexible and easily bends inside the electrical panel. This simplifies installation, especially if many machines are installed in the switchboard. Further, the internal insulation is removed from the wires by about 5-10 mm.
To connect small wires or stranded wires to the machine, it is advisable to use special terminals.
Where are used and how are one-, two-, three- and four-pole machines connected
In single-phase networks with a voltage of 220 V, single-pole or double-pole machines are usually installed to protect electrical appliances.
- Only the phase conductor is connected to the single-pole circuit breakers - L.
- Both wires are connected to two-pole, phase - L and neutral wire - N.
- Three-pole circuit breakers are used in 3-phase networks. Three phases of the power supply L1, L2, L3 are connected to the terminals of such machines.
- Four-pole machines are used in places stipulated by the rules of the PUE. As a rule, these are four-wire networks with a solidly grounded neutral, in which three phases L1-L2-L3 are used and a zero working one - N (TN-S system).
The main mistakes when connecting machines
- Let's analyze the most common errors:
- connection of the ends of the conductors of a flexible stranded wire without termination;
- contact with insulation;
- connection of conductors of different cross-sections to one terminal;
- soldering the ends of the veins.
The main mistake when connecting machines is the use of a flexible stranded wire without termination. It's easier and faster this way, but not right. Such a wire cannot be clamped securely; over time, the contact weakens ("flows"), resistance increases, and the junction heats up.
It is necessary to use lugs on a flexible wire or use a solid solid wire for installation.
Everyone knows that before connecting the machine in the dashboard, you need to remove the insulation from the wires to be connected. It would seem that there is nothing complicated here, I stripped the core to the required length, then we insert it into the clamping terminal of the machine and tighten it with a screw, thereby ensuring reliable contact.
But there are cases when people are at a loss why the machine burns out when everything is connected correctly. Or why the power in the apartment periodically disappears when the wiring and filling in the dashboard are completely new.
One of the reasons for the above is that the wire insulation gets under the terminal of the circuit breaker. Such a danger in the form of poor contact carries the threat of melting of the insulation, not only of the wire, but also of the machine itself, which can lead to a fire.
To exclude this, you need to follow and check how the wire is tightened in the socket. Correct connection of the circuit breakers in the switchboard should exclude such errors.
Never connect the machines with jumpers with cables of different cross-sections. When tightening the contact, a conductor with a large cross-section will be well clamped, and the one with a smaller cross-section will have poor contact. As a result, the insulation melts not only on the wire, but also on the machine itself, which will undoubtedly lead to a fire.
- An example of connecting circuit breakers with jumpers from different cable cross-sections:
- The first machine receives a "phase" with a wire of 4 mm2,
- and other machines already have jumpers with a wire of 2.5 mm2.
As a result, poor contact, temperature rise, insulation melting not only on the wires, but also on the machine itself.
For example, let's try to tighten two wires with a cross section of 2.5 mm2 and 1.5 mm2 in the terminal of the circuit breaker. No matter how hard I tried to ensure reliable contact in this case, nothing worked for me. A wire with a cross section of 1.5 mm2 dangled freely and sparked.
Separately, I would like to dwell on this method of terminating the wires in the shield as soldering. Human nature is so arranged that people try to save money on everything and do not always want to spend money on all kinds of tips, tools and all kinds of modern small things for installation.
For example, consider the case when Uncle Petya, an electrician from the housing office, conducts the wiring of the electrical panel with a stranded wire (or connects outgoing lines to the apartment). He does not have NSHVI tips. But there is always a good old soldering iron at hand.
And the electrician Uncle Petya does not find any other way out how to irradiate the multi-wire conductor, stuffs the whole thing into the contact terminal of the machine and tightens it heartily with a screw. Why is such a connection of automatic machines in a switchboard dangerous?
When assembling the switchboards, DO NOT solder or service the stranded conductor. The fact is that the tinned compound begins to "float" over time. And in order for such a contact to be reliable, it must be constantly checked and tightened. And as practice shows, this is always forgotten.
The soldering begins to overheat, the solder melts, the junction is weakened even more and the contact begins to "burn out". In general, such a connection can cause a FIRE.
How to properly connect an electric meter and vending machines
- For the safe operation of your shield, follow these simple rules:
- use a single-wire monolithic wire for installation;
- when using a flexible wire, use ferrules;
- use non-breaking jumpers;
- use a U-fold to increase the contact area.
Using lugs on flexible wires
For wiring switchboards, electricians often prefer a flexible wire with a multi-wire conductor of the PV-3 or PuGV type. It is easier and easier to work with it than with a monolithic vein. But there is one peculiarity here.
The main mistake that beginners make in this regard is to connect a stranded wire to the machine without termination. If you clamp the bare stranded wire as it is, then when tightening, the veins are squeezed and break off, and this leads to a loss of section and deterioration of contact, and the contact itself has been weakening from time to time.
Experienced "experts" know that it is impossible to tighten the bare stranded wire in the terminal. Therefore, if a stranded wire is used during installation, then NSHV or NSHVI tips must be used to terminate it.
In addition, if there is a need to connect two stranded wires to one terminal of the machine, for this you need to use a double lug NSHVI-2. It is very convenient to use it to form jumpers for connecting several group machines.
Using a U-fold
To connect the veins of outgoing wires and cables to the machines, we remove the insulation from them by about 1 cm, insert the bare part into the contact and tighten it with a screw. According to statistics, 80% of electricians are connected this way.
The contact at the junction is reliable, but it can be further improved without wasting time and money. When connecting cables with a solid core to the machines, make a U-bend at the ends.
This formation of the ends will increase the contact area of the wire with the terminal surface, which means that the contact will be better.
The inner walls of the contact pads AB have special notches. When the screw is tightened, these notches cut into the core, which increases the reliability of the contact.
If there is a need to connect several machines standing in the same row from one source (wire), a comb bus is the best fit for this purpose. But these tires are not always at hand.
How to combine several group machines in this case? Make a homemade jumper from the cable cores. To do this, use pieces of wire of the same cross-section, or it is better not to break it at all along its entire length.
- How to do it:
- Without removing the insulation from the wire, form a jumper of the desired shape and size (according to the number of branches).
- Then we strip the insulation from the wire at the bend to the desired length, and we get an unbreakable jumper from a single piece of wire.
Today, almost no object can do without electricity, since they need sockets for connecting electrical equipment and lighting of premises. All apartments, houses, offices, garages, warehouses and so on have an extensive power supply network. To protect it, for the electrical safety of people, for effective management of the power grid, it is necessary to install electrical distribution boards. They contain switching protective devices that perform all of the above functions. The switchboard is divided into groups, which makes it possible to achieve convenient and independent operation of powerful household appliances.
All objects are different and, accordingly, their power supply networks will also be different. Below we will consider a few simple examples, which show five options for single-phase power supply schemes for apartments and private houses.
General principles for constructing any dashboard scheme:
- The input must have an input switching device. It can be a circuit breaker or a circuit breaker (load switch).
- All group lines outgoing from the board must be protected against overload and short-circuit currents.
- All receptacles must be protected against electric shock by a person. For these purposes, residual current devices (RCDs) or difavtomats with a leakage current of 10-30mA are installed.
Option 1
This is the simplest diagram of an introductory board with an electricity meter. It shows the TN-S grounding system, that is, when separate independent zero working and zero protective conductors come from the power source. In this single-phase circuit board, a two-pole circuit breaker is installed at the input.
Here and in the following diagrams, the ratings and characteristics of the protective devices are randomly selected. They may differ for you, but the very essence of the connections between circuit breakers and other protective devices remains the same.
After the introductory machine comes the counter. To be taken into account, the input switching device and the electricity meter itself must be sealed. Next are single-pole group circuit breakers. The phase is always fed to the circuit breakers, and zero to the zero bus. It so happens that all zero working conductors of different groups are combined with each other, and the phase conductors are switched using automatic machines.
This version of the scheme is the simplest and is very often found at various objects.
Option 2
This version of the shield is similar to the previous scheme. There is only no electricity meter. Such options for boards are used if the meters are located on the street in metering boards or on the staircase in floor boards. The first option is relevant for the private sector, and the second for apartment buildings. Since almost all connections between protective devices are described in the first version, there is nothing special to comment on here.
The only thing that can be noted here is that at the input, instead of installing a circuit breaker, you can choose a switch (load switch). It is required to manually disable the entire shield. Installing an automatic machine here will lead to duplication of the nominal value of the input circuit breaker from the metering board or from the floor board. You don't need to do this.
Option 3
As I wrote above, all groups of outlets must have protection against current leaks, that is, they must be protected using an RCD. In the third version of the circuit, an introductory RCD is presented, which is installed after the meter. An RCD cannot be installed before the metering device, since it will need to be sealed, which the inspectors do not want to do. Therefore, they allow it to be installed only after the counter.
To protect a person, you need to use an RCD with leakage currents of 10-30mA. This is a safe current for a person, in which he is able to withdraw his hand and not receive any injury. The option using one 30mA RCD at the input has one drawback. When it is triggered, the entire apartment, house, etc. is turned off. Also, if the network is highly branched, then the RCD may operate falsely due to natural leakage currents that are present in every household appliance.
In this embodiment, the phase and zero are fed to the input contacts of the RCD. Further, from the output contacts, the phase is fed to the circuit breakers, and zero to its zero bus. Remember that zero before the RCD and zero after it cannot be combined with each other, that is, connected to the same bus. Otherwise, you simply will not cock the residual current device, since it will turn off immediately.
Option 4
In this version of the circuit, a fire-prevention RCD for 100-300 mA is installed at the input, and then some groups are protected by individual RCDs for 10-30 mA. To exclude the simultaneous operation of the input and group devices at the input, it is recommended to install a selective RCD. It has a time delay for actuation and is designated on the body by the Latin letter "S".
In this scheme, you need not get confused with the connection of zero working conductors. Zeros after different RCDs cannot be combined with each other, otherwise the devices will turn off immediately. Therefore, after each RCD, you need to put your own zero bus if several groups are connected to it, or the zero working conductor must be immediately connected to the RCD if it protects one group. This is shown in the diagram below.
Option 5
In this variant, difavtomats and conventional circuit breakers are used to protect groups. Residual current circuit breakers (RCBOs) protect the cable from overload, short-circuit current and protect a person from electric shock. For each difavtomat, phase and zero must be applied. It is also impossible to concatenate zeros after exiting these devices. Zero working conductors of the remaining groups, which are protected by conventional circuit breakers, are connected to the input common zero bus.
This article presents the simplest options for single-phase electrical switchboards. Almost all protective devices are considered in them, it is shown how they need to be connected and there are descriptions of the use of one or another option. Based on your individual situation, you must develop your scheme. Remember that it must meet all modern electrical safety standards.
We mount the electrical panel ourselves
The importance of the electrical panel in the apartment in the power supply system of the house is extremely high. The wiring will not be able to function efficiently and fully without proper distribution of electrical energy consumers, and fire and electrical safety will be minimized in the absence of the necessary protection elements. Of course, it will be better if specialists will be engaged in laying wires and installing equipment, but with some study of this issue (this article will help you with this), you will be able to independently install the electrical panel with your own hands without much effort and cost by assembling a simple electrical circuit. The main thing is to figure out what power supply schemes are, what equipment you need to choose, how to calculate electrical loads, how to distribute them correctly and evenly.
General questions about electrical panels
At the moment, there are two types of electrical panels. The first - old and fading into oblivion - a panel with fuses (or plugs), which were disposable, and they had to be unscrewed for replacement, and modern devices equipped with systems of packet switches (automatic machines). Of course, it is better to use modern technologies, since they surpass outdated systems in terms of reliability, safety and durability, and they take up less space, but they are not repaired. In stores, you can buy shields with built-in circuit breakers, as well as empty "boxes" and already install the necessary equipment yourself.
An electrical panel in an apartment, the power supply scheme of which can be varied, and the number of consumers and their power may increase over time, should be selected with additional places for circuit breakers.
An introductory machine, usually capable of simultaneously disconnecting both "phase" and "zero", should be selected based on the total load of the apartment. The value of its current and protective characteristics is higher than that of auxiliary machines. As a rule, an automatic machine for 32-40 amperes (about 7 kW) is suitable for two- and three-room apartments, if the load is less, the machine can be taken for 25 or 16 amperes.
As for the auxiliary circuit breakers installed on the "phase", they are necessary to protect a separate room or device. Experts advise installing such an automatic machine for each consumer whose power exceeds 1.5 kW (heating tanks, washing machines, and so on). A table of approximate loads of electrical appliances is located below.
Table 1 - approximate capacities of household appliances.
An RCD (Residual Current Device) is an extremely useful device if you need to increase the level of electrical protection at times. They react to the slightest leakage of currents and voltages, instantly de-energizing the circuit. If there are bathrooms and children's rooms in the house, equipped with electrical appliances,.
RCD power distribution Installation and device of the shield
The electrical panel for apartment abb or legrand is of two types:
- Closed (recessed into the wall).
- Open (the shield is attached directly to the vertical surface).
The choice of the type of installation mainly depends on the type of wiring - if the open-type wiring is ideal, the installation of an overhead shield will be ideal - such a shield does not require special preparation of the place, fastening to the wall is carried out using ordinary dowel-nails or screws "self-tapping" (it all depends on the material of the wall) ...
If the wiring is of a hidden type (i.e. built into the wall), then the best option would be to install a built-in shield. Everything is more difficult here, since you have to hammer the walls. The main thing is not to forget to make sure that the thickness of the wall allows you to install the shield. After creating a niche, it is coated with a fixing solution of gypsum or alabaster, and already a "box" is built into such a bed. It is more convenient to use a plastic shield. The upper part should contain input machines, under which the counter is located. It is secured with screws. The installation of the meter is carried out after the end of the work related to the wiring device. This is due to the filling.
The installation of the electrical panel should be carried out on a hard surface - in a place where it is easy to access and maintain.
According to the norms, the location of the shield, it is installed away from the water and gas pipelines. It should be located on a flat wall surface with an angle of inclination of no more than 1.5 degrees at a height of about 1.5 meters from the floor. If it is not possible to place the meter far from the places of potential damage, then it can be placed in a cabinet equipped with an observation window. Fastening of wires is allowed using bandage binding.
For wiring in the attic, it is necessary to leave a short wire, because it is not allowed to twist the wire into a coil. If you are installing electrical wiring in the attic, the cable is placed in a metal pipe with grounding.
As for the materials from which the shields are made, it can be either metal or heat-resistant plastic. The second option is more convenient to install and operate, safer, and its appearance is attractive.
So, we have dismantled the installation of the box itself, now we will figure out how the circuit of the electrical panel is arranged. 
In principle, all electrical circuits of panels are of the same type, but there are main factors by which they are assembled, these include:
- the number of consumers of electrical energy;
- total power consumption of electrical energy;
- the power of each consumer;
- place of installation of the electrical panel;
- number of phases;
- the presence of a grounding conductor;
- the presence of a metering unit for electrical energy.
The voltage is supplied to the input automatic device (it is better if it is two-pole) and goes to a single-phase electricity metering unit, from where it is fed to the RCD. Further, there is a phase splitting and direct distribution of loads using circuit breakers and additional RCDs. For example, there will be machines separately for lighting, for sockets and for powerful consumers.
The device of the electrical panel with a three-phase power supply system is similar, only the introductory machine, the RCD and the electric meter will be three-phase, and the whole system will be larger both in terms of dimensions and in the number of machines and connecting conductors.
We start the internal installation
Now let's figure out how to properly assemble the electrical shield. First and foremost, a din-rail is installed in the shield using self-tapping screws. From itself, it is a metal plate, to which all switching devices will subsequently be attached. To create the required length, it can be easily cut with a hacksaw for metal.
In addition to the din-rails, terminal blocks are attached to the shield body (in a different way, distribution busbars). Their role is to connect neutral conductors. If an apartment or house of an old model and the entire system is made only by a phase (3 phases) and a working zero (performed with a blue wire), one terminal block is enough. If the system is made according to the rules and there is an additional yellow-green conductor (protective zero or ground), then another bus must be installed. At the moment, there are tires on sale, the design of which allows them to be mounted on a din rail, like machines.
After mounting the DIN rails, we proceed to fixing the circuit breakers. The modern design will make it possible to do this very quickly, it is enough to pull off the latching device on the upper side of the machine with a flat screwdriver, put the machine on the DIN rail and remove the screwdriver. Removal is carried out in the same way.
Assembly instructions
The connection can be made in three ways:
- With the help of stranded copper wires with ferrules type NSHVI.
- Make U-shaped jumpers from pieces of copper wire with your own hands.
- With the help of special insulated busbars called combs. Such a bus is convenient in terms of installation and does not take up much space, plus several times it reduces the number of connecting wires.
Following actions:
What else do you need to know?
Installing an electrical panel and assembling it is not only the ability to correctly assemble circuits. You also need to know some of the nuances in order not to regret the time and effort spent later.
It should be recalled that it is necessary to assemble and install the Legrand, ABB electrical panel or equipment of another company strictly on the disconnected power line, after checking the absence of voltage.
To connect the assembled shield to the operating system, it is necessary to involve employees of the relevant organizations. For apartment buildings, these are representatives of the HOA or ZhEK.
As a result, after the end of the entire assembly and connection process, you need to close or screw the cover and check your work by applying voltage to the live parts of your shield.
Wiring diagram with three input phases 
Single-phase connection diagram 
Wiring diagram in the apartment
When connecting private houses to an external power supply system, homeowners face various problems and mistakes:
- inconsistency of the technical characteristics of the input equipment with the actual loads on the electrical network;
- insufficient level of electrical safety of a home electrical installation, the reason for which is the lack of necessary protection devices against electric shock;
- errors during connection of protective devices and violation of the sequence of their connection.
All this is caused by the lack of objective information on how to properly supply electricity to the house and what equipment should be equipped with an introductory electrical panel.
More precisely, there are many answers to existing questions, but it is not so easy to find reliable information in them.
Electrical installation rules PUE, building codes, requirements of local power grid companies - if you delve into all this at the same time, you can quickly come to a dead end. Therefore, we would like to acquaint you with the real experience of FORUMHOUSE users and the recommendations of the Legrand Group specialists, our partners in the project.
Connecting power-receiving equipment in a private house is a matter that must be dealt with by professionals. However, after reading the article, you can take note of a few recommendations for yourself.
Today you will learn:
- what are the requirements for the design of electrical panels;
- what devices should be equipped with electrical panels, and what functions the installed equipment performs;
- how to ensure the selectivity of a home electrical installation;
- how to choose a protective device according to its performance;
- in what sequence to connect protective devices (RCDs, difavtomats, circuit breakers (AB)).
Organization of the insertion point
In the process of connecting a cable line (underground or overhead) to the switchboard (PD) mounted in the room from the street electricity metering board (SCHU) located on the power transmission line branch support to the distribution board (DC).
In the metering board (SCHU), often, there is only an introductory machine and an electricity meter. Circuit breakers, residual current devices and other elements, which will be discussed below, are mounted in the switchboard (PD), which is installed directly in the house.
In some cases, the equipment for the control panel and the switchboard can be installed in one housing.
The operating parameters of the equipment installed in the metering panel, its list and quantity - all this must be spelled out in the power supply project (or, at least, must be calculated by specialized specialists). But there are requirements that apply directly to the design of the electrical panel.
Sergey Saveliev Head of the technical department of the Legrand Group in Russia
The design of the electrical panel should ensure the convenience of supplying the power cable; it should contain zero buses and grounding buses. In this case, the electrical panel must have an internal space sufficient to accommodate numerous outgoing cables, and its margin necessary for possible expansion and modernization of the electrical installation.
We add that the body of the shield must be resistant to fire or be made of self-extinguishing material. At the same time, he is obliged to reliably protect the built-in equipment from possible damage. A lock built into the door or the handle of the flap will help against intentional damage, and protection against dust and moisture is guaranteed by the IP degree of protection specified in the specification. If the shield is supposed to be installed outdoors or indoors, where increased protection against moisture, dust and mechanical damage is required, then it is better to give preference to shields of IP65 –IK09 class.
In order to avoid disagreements with the specialists of power supply companies during the connection process (whose requirements often contradict each other), simultaneously with the architectural project, a power supply project should be developed and agreed upon.
If the connection point is organized in accordance with the requirements of the agreed electrical project, the site owner usually does not have problems in the connection process and further checks by the controlling organizations. Therefore, the labor associated with installing and completing the electrical panel will not be in vain.
Let's talk about what the complete set of a home switchboard should be.
Input switch and metering device
The starting point of the home electrical installation is considered to be the input switch to which the electricity meter is connected, and the rest of the devices located after the meter.
Sergey Saveliev
The rating of the input AB is determined by the power supply organization, based on the allocated power. For example, with a three-phase input and 15 kW of dedicated power, the nominal value is 25A. With 1-phase input and 7.5 kW, the nominal is 40 A. Moreover, if the power is more than 11 kW, the power supply must be three-phase. If there are three-phase consumers in the project, a three-phase connection is allowed with an allocated power of less than 11 kW.
Reserve input device
If the electrical installation includes a source of autonomous power supply (for example, a diesel generator), then the system must have a reserve input device, which is installed after the electricity meter. This is a switch that allows consumers to be manually connected to a generator or to an external power supply system. This device does not allow simultaneous operation of two different power sources (transformer substation and diesel generator). This is its key advantage.
SPD
To protect an electrical installation from high-voltage impulses, from the consequences of a direct lightning strike and, as a result, from possible fires, it is necessary to integrate a surge protection device (SPD) into the system.
In the general diagram, SPDs are located immediately after the QF1 lead-in device. In addition, the SPD should be connected to the circuit through a separate QF2 protection device (circuit breaker or fuse). The number of poles of the input device and the SPD should be selected based on the number of phases and the mode of operation of the neutral. (see diagram). When entering a building with air, the installation of an SPD is a must!
Fireproof RCD
Fire protection devices are designed to protect against fire. As fire-prevention RCDs, devices are used that operate on a rated differential current - from 100 to 300mA. This is a fairly large setting and does not protect a person from electric shock. For this reason, certain groups of consumers are equipped with additional (more sensitive) RCDs.
Recently, selective fire protection RCDs have become widespread.
Sergey Saveliev
Type "S" (selective delayed RCD) is designed so that in case of ground faults in lines (for example, in outlet lines), only the downstream RCDs of a particular line are triggered, and the fire-prevention RCD at the input continues to work, feeding serviceable sections of the wiring.
Cross module
In modern power supply systems, several groups of electrical consumers are often used (socket group, lighting, etc.). And in order to distribute the electricity supplied to the shield from the input cable between the various groups, it is recommended to install a modular distribution block (cross-module) on a DIN rail. The cross-module allows one conductor to be inserted into the shield, designed for a large load, and to obtain at the output several lines of a smaller section (which depends on the load on a particular group of consumers).
In addition, the installation of a cross-module ensures the reliability of electrical connections and simplifies the process of connecting additional devices to an existing electrical panel.
RCDs and circuit breakers (AB) for individual groups
Each consumer line leaving the cross-module is protected by separate automatic devices and RCDs. When it comes to installing them in a switchboard, two questions immediately arise:
- How to choose the right protective devices for their rating and differential cut-off current?
- How and in what sequence are RCDs and machines connected to each other?
We will try to give detailed answers to them. First, let's find out what functions the presented devices perform:
- RCD protects a person from electric shock, while it cannot protect itself and the electrical installation from overcurrents and short-circuit currents. Therefore, the power supply system must be equipped with both an RCD and AB at the same time.
- Circuit breakers do not react in any way to leakage currents, but protect the circuit from overloads and short circuits.
The protective action of the RCD is based on the principle of limiting (due to quick disconnection) the duration of the current flowing through the human body when it unintentionally touches the elements that are energized. Under normal conditions, the current flowing through the neutral wire is exactly equal to the current in the phase wire. If there is a difference between them due to ground leakage through damaged insulation or through the human body, the device reacts to this by immediately disconnecting the network.
To understand what rating the protection devices should have, let us turn to the opinion of a specialist.
Sergey Saveliev
Socket lines (cable cross-section 2.5 mm²) are protected by AB for 16A, lighting lines (cable cross-section 1.5 mm²) AB for 6 or 10 A. Consumers with a power of more than 3.5 kW are connected to the switchboard with a separate cable through a separate AB. In this case, the cable cross-section and AB rating must be calculated.
On the AB case, the letter designation of the category of the device by operating current is always applied (for example, B16, C16). The number after the letter indicates the nominal value of the device in amperes. In household systems, AB of the following categories are used: "B" and "C". Devices of category "B" operate almost instantly when the current in the circuit rises to 3-5 ratings. Category C devices are rated for instantaneous tripping at 5-10 ratings. Consequently, automatic machines of category "B" are most sensitive to short-circuit currents and are especially recommended for wooden housing construction.
Now, with regard to RCDs: these devices are selected at once according to three parameters:
Sergey Saveliev
An RCD of 30 mA is placed "at the head" of a group of circuit breakers (for example, 3-4 machines are connected to one RCD). In this case, the rated current of the RCD should be no less than that of the superior AB (as a rule, the superior is the input AB).
So, several ABs can be connected to each RCD, protecting individual groups of consumers.
R0c0t FORUMHOUSE user
Rooms with a high level of humidity (bathrooms, showers) are recommended to be protected by an RCD with a differential breaking current of 10 mA, if a separate line is allocated to them. In other cases, for example, if one line is allocated to several rooms (kitchen, bathroom, etc.), an RCD with a differential operating current of no more than 30 mA (SP 31-110-2003) should be used.
Connection sequence for RCDs and circuit breakers
The first connection rule: if a phase is taken from one RCD, then zero from all consumers connected to this phase must return to the original RCD. That is, the neutral and phase wires should not be mixed with other zeros and phases after the RCD.
In the diagram, we see two machines going to the lighting groups (protection of lighting lines with an RCD is not mandatory). The fire protection RCD is not indicated in this diagram. Socket groups are protected by a protective shutdown with a rating of 40 A and 30 mA.
The connection is simple:
- the lighting groups are not connected to the RCD, therefore, the branch of the neutral and phase wires on them is carried out after the introductory machine;
- the phase for the outlet groups is taken from one RCD;
- the zero of the socket group is supplied to a separate zero bus, which is also connected to the RCD.
When completing electrical panels, situations should be avoided in which an unlimited number of lines are connected to one RCD. To ensure this condition, the standard panel is equipped with several residual current devices. RCDs in this case are grouped by the types of connected rooms and by the type of load. For example, the outlet group of the bathroom is connected to an RCD with a nominal value of - 10 mA, and the outlet groups of the kitchen and living quarters are connected to an RCD with a nominal value of - 30 mA.
Differential automata
In practice, differential circuit breakers are often used instead of residual current devices.
These are devices that combine RCD and AV in one case. It makes sense to use difavtomats if this device will protect a separate line or an individual consumer. If you protect several lines with a difavtomat, then each will need to additionally install its own AB (unless, of course, the selectivity of the system is important to you, and you do not want to violate it).
