Overview of surge protection devices in the network. Causes of electrical wiring fire in the apartment Installation of a switchboard

IN modern home impossible to do without electricity. All kinds of equipment that supports the comfort and life support of the inhabitants of the house needs a high-quality and safe electrical network. Properly executed electrical wiring that provides safe and uninterrupted power supply to the house with electricity is not an easy task, but it is quite within the power of many owners. The main thing is to correctly understand and comply with all the principles and requirements for the performance of work on the electrification of residential and utility rooms.

In order to properly install the internal house wiring line, it is necessary to understand the types of electrical wires, their purpose, as well as other basic concepts.

Wires and cables

• electrical wire- metal conductor of electric current. It can be made of aluminum or copper wire. Consists of one or more insulated or non-insulated conductors.

Often, aluminum wires are used for internal wiring, although they are inferior to copper wire in many respects. The only advantage that aluminum wires have is that they are not high price. With the same current loads, the cross section of the aluminum wire should be larger than the cross section of the copper wire, and this is inconvenient. Physical Properties metal aluminum wires cause a less reliable connection than copper wires. In addition, aluminum has a high oxidizability, which affects the electrical contact of aluminum wires with each other and with wires from other metals. Because of this, all mechanical contacts of aluminum wires require periodic compression, otherwise heating will occur at the point of contact and, as a result, a possible fire. In addition, oxidizing, aluminum affects the vinyl insulation of wires and it collapses over time.

The modern market offers many solutions to the problems mentioned above. This is a whole range of solid and stranded, solid and stranded copper wires of the PV series, the cross section of which can be selected for any expected current load. Double-insulated wires of the VVG series (vinyl - vinyl - bare) have increased reliability and are therefore very convenient for external and internal wiring in suburban and cottage construction. In those rooms where increased requirements are placed on the reliability and safety of wiring, PUNP wires (wire - universal - flat) with reinforced insulation can be used.

• Electrical cable - several insulated electrical wires having a common protective sheath. Also, for protection against external influences, a metal hose (steel spiral tape or metal braid) can be made over a conventional shell.

In specialized stores, there are many offers for choosing electrical cables. Among various types cables are multi-core and single-core. For fixed wiring, it is better to choose a single-core cable. Such a cable has an increased resistance to mechanical stress, it is less susceptible to oxidation and, as a result, loss of contact. In the same place where the wiring will be subject to movement (for example, when replacing electric lamps or moving electrical appliances) the use of a flexible multi-core electrical cable, such as PVA (wire - vinyl - connecting), is more preferable.

In areas with a high fire risk, NYM cables are recommended.

NYM is the German name for:

• N - manufacturing standard (Normenleitung);
• Y - PVC insulation material;
• M - outer protective shell (Mantelleitung).

These cables have a fireproof packing that releases flame retardants when heated. For rooms with high temperatures, e.g. sauna, etc. there are heat-resistant cables that can withstand temperatures up to 800 ° C. In addition, these cables are moisture resistant and plastic.

• Electrical cord- a multi-wire flexible electrical cable designed specifically for connecting electrical appliances to the network through electrical connectors (sockets).

Characteristics of electrical wires

The parameters characterizing various electrical wires are divided according to the dependence of their cross-sectional area on the permissible value of the passing current. In order to determine the required cross-sectional area of ​​the wire, it is necessary to know the expected maximum current passing through the wire, taking into account the heating of the insulation. The permissible operating temperature for heating electrical wires should not exceed 65-70°C (depending on the insulation material). With a value room temperature 25°C, the allowable heating of the insulation is 40-45°C. Given these conditions for the cross section of wires made of copper and aluminum, using the tables below, you can determine the permissible current loads.

If the cross-sectional area is unknown, then it can be calculated by the formula:

S = 0.785 d²,

where S is the cross-sectional area in mm², d is the measured (with caliper) wire diameter in mm.

The cross section of a stranded wire is determined by summing up the cross sections of all the wires in the wire.

The most used modern cable for laying electrical wiring inside the house is the VVG copper cable with two layers of insulation. Such a cable is designed for a current with a voltage of 600 and 1000 V, and a frequency of 50 Hz. When using this cable, you can use the following recommendations for choosing a section:

1. Wiring for lighting and security systems - 1.5 mm².
2. Wiring for consumers with a power consumption of not more than 3.5 kW (including sockets and other electrical connectors) - 2.5 mm².
3. Wiring for consumers with a power consumption of more than 3.5 kW, but not more than 5.5 kW - 4 mm².

Electrical wiring inside the house

Electrical wiring inside the house is laid in two ways. The first way is open wiring. The second way is hidden wiring.

open wiring

Open wiring is used if the walls are already fully completed and finally lined or there is no need or desire to hide the wires. In wooden houses, open wiring is the norm of modern safety requirements. In a wooden house (unlike a stone one), the wiring can be damaged by rodents, and the accumulated wood dust instantly ignites in the event of a short circuit.

Exposed wiring is easy to install, easier to maintain and control, and can be moved or added as needed. If earlier, when performing open posting on wooden walls the contact of the wire with the tree was not allowed (it was necessary to maintain a distance of 15-20 mm), now this is permissible. Wires can be laid along the surface of the wall, fixing them with electrical clips of a suitable size. The distance between the clips is selected based on the stiffness of the wire, but not more than 1 m. The main condition for the contact of the wire with wooden wall- this is the presence of at least double insulation (VVG cable).

Open electrical wiring can be made in a corrugated polymer pipe. Several wires can be placed in such a pipe at the same time. Although safety will be observed in this case, the aesthetics of such wiring, especially in residential areas, will leave much to be desired. In addition, if you need to gain access to a separate section of the cable (or a separate cable), you will need to dismantle a large amount of wiring.

The electrical wiring made in polymer cable channels with a removable cover looks quite neat and harmonious. They come in a variety of sizes, capacities, colors and are made from non-flammable plastic. Cable channels are easy to install and convenient for wiring maintenance and when making additions and changes. There are many cable channels accessories– bends, external and internal corners, tees and plugs.

For open wiring, copper wires are used. If you use aluminum, then when passing combustible wall structures, you will have to use a layer of sheet asbestos with a thickness of at least 3 mm and protruding from each side of the wire by at least 5 mm. This is inconvenient and unaesthetic.

Hidden wiring

Hidden wiring, as a rule, is carried out before plastering or facing works. The advantages of hidden wiring are:

• reliable protection of wires with a layer of plaster coating from mechanical, thermal and light effects;
• the ability to conduct wiring between two junction boxes or leads to sockets and switches in the shortest way, which will save the wire (but only strictly vertically and horizontally for safety reasons);
• aesthetic effect.

Installation of electrical wiring

Required Tool

Depending on the material of the walls and other conditions, the list necessary tool will change. However, there is a list of tools that you can not do without in any case. You will definitely need the following tools:

1. Screwdrivers of various sizes, both flat and Phillips.
2. Passive and active probes.
3. Knife construction or clerical.
4. Pliers.
5. Side cutters or nippers.
6. Wire stripping tool.

Electrical route marking

In order to conduct wiring, you need to know the installation locations of the electrical panel, junction boxes, sockets, switches and fixtures.

• Electrical panel.

The electrical panel is usually installed in the immediate vicinity of the entrance to the house and, as far as possible, from the input of an external electrical cable. The place for the electrical panel must be protected from dampness (moisture) and possible mechanical influences (for example, when bringing furniture into or out of the house, etc.). The electrical panel is attached to a wall or other rigid structure that is not subject to shaking, away from heat sources at a height of 1.4-1.7 m from the floor.

The electrical panel must be easily accessible for maintenance, as well as switching on and off the general switch and safety devices.

• Sockets.

Sockets are placed taking into account the layout of the room and the number of possible electrical appliances. Sockets are not redundant. It is better to install more sockets, including double or even triple and quadruple, than to abuse extension cords and tees later.

Sockets are best placed at a height of 300 mm from the floor, and located above desks and in similar places - at a height of 1000 mm.

• Switches.

Places are selected for switches in the room, depending on the location (ceiling and wall), type (stationary and mobile) and quantity lighting fixtures.

There can be several switches (for each lighting device) or one multi-key switch for several lamps.

The height of the switches is chosen approximately at eye level (1600-1800 mm from the floor) or at the level of the palm of the lowered hand (700-900 mm from the floor).

• Junction box.

After all the places for the shield, sockets and switches are determined, a place is chosen for the junction boxes. Moreover, the less they are needed, the better (additional connections are the complexity of installation and a source of additional danger).

Distribution (branch) boxes can be placed both in the room itself and in the corridor. Depending on where it goes common line, at the same level (in height) the junction box itself is located.

• Wiring.

The wiring line is placed:

• for sockets directly at the same level where they are located;
• taps to lamps and switches vertically, in order to avoid the risk of short circuit when driving nails or dowels during the subsequent arrangement of the room;
• for lighting and sockets in separate groups (mains);
• for computer equipment a separate highway.

Wire laying

After the markup is completed, proceed to the direct laying of the wire.

Laying the wire of open wiring does not cause any particular difficulties. In addition, the main methods of fastening and laying the cable have already been discussed above.

The main thing in any method of laying electrical wiring is accuracy and compliance with all the rules for the safe execution of the electrical network at home.

When installing hidden electrical wiring, the wire is laid in a groove made in the wall. The groove (channel or strobe) is made of the required width (slightly wider than the diameter of the wire or the cable protection used). The cable is laid in a groove and fixed with alabaster or cement mortar. After the installation is completed, the groove is puttied.

Simultaneously with the grooves for the wire, nests are made for distribution and installation boxes, sockets and switches.

In brick, block or concrete walls the groove is selected using a grinder (with the desired type of disc) and a puncher. If there are seams in the wall (block or brickwork), then the grooves should be aligned with them (both horizontally and vertically).

The width of the groove is slightly larger than the diameter of the round cable or the thickness of the flat cable, and the depth is 8-10 mm more than the diameter of the round cable or the width of the flat cable.

After the junction boxes are installed (and the input and output windows are correctly oriented), you can start laying the prepared cable or wire sections into the grooves. In this case, the free ends of the wires are brought into junction boxes with a margin of 150-200 mm.

If the walls are made of drywall or other facing material, then the cable is pulled behind the lining from box to box along the shortest path. In drywall (or other cladding material), holes are cut for junction boxes (special for this material), and then they are mounted using special mounting screws.
When laying a cable in metal or plastic pipes, the cable is pulled through them with a conductor (steel wire or cable).

Electrical wiring in the house. Installation of sockets, switches and lamps

Sockets and switches have in their design special terminals for connecting wires. There are four types of terminals:

1. Screw with washer.
2. Screw with square nut and terminal plate.
3. Terminal and screw on the side.
4. Special mechanical clamp with spring (no screws).

The operation of stripping the end of the cable requires special care, this is done as follows:

1. With a sharp mounting knife, an incision is made along the outer insulation of the cable (it is necessary to act carefully so as not to damage the insulation of the wires inside).
2. The incision is made along the length of the wire that is connected to the most remote terminal.
3. Bend the incised part of the outer sheath of the cable, freeing the inner cores, and cut it off.
4. Cut each core to the required length, taking into account the location of the terminals.
5. Strip the insulation of each core, leaving a piece of uninsulated wire 6-12 mm long (the edge of the wire insulation should be as close as possible to the terminal, which reduces the risk of a short circuit).
6. To strip the ends of the wire in the right place, make an annular cut of the insulation (carefully and slightly so as not to damage the wire), and then pull the insulation off with pliers.
7. The remaining ring scratch can lead to a crack, and then to a wire break at the terminal. Therefore, when cutting the insulation, the knife blade must be held at an angle to the core, but it is better to use a special tool for stripping the insulation.

After stripping the ends of the wires, they must be connected to the terminals. The wires in the cable usually have different colors of insulation. It is customary to use a blue (brown) wire for the phase wire, black (or white) for the zero wire, and yellow-green for the ground wire. But the most important thing is that in all rooms of the house the marking should be the same.

When laying a home electrical network, sometimes installation boxes of sockets are simultaneously used as switching boxes. Both the inlet and outlet wire are attached to each terminal at the same time.

When mounting the switch, the phase wire is attached to the movable contact terminal, and the neutral wire is attached to the fixed contact terminal. If the switch has several keys, all moving contacts are connected to one terminal (to which the phase wire is connected), and neutral wires are connected to the terminals of the fixed contacts. Neutral wires are brought to the fixtures (or groups of fixtures) as phase wires, they are connected to the central contact of the electric cartridge. The wires from the threaded contact into which the lamp base is screwed are connected to the neutral wire.

If it is necessary to install several sockets (or several sockets and switches) in one housing in one place, you can use special installation boxes with adapters that combine all devices into one unit.

Electrical wiring in the house. Wiring

Electrical wiring at home consists of many elements. All these elements will eventually need to be connected into a single network. Each connection (switching) must be reliable and secure. All connections must be made only in the junction box. The junction box must always have free access to it (not be plastered or tightly sewn in) and located in accessible places (without additional actions to free up space for access to it).

Basically, for switching wires, the method of twisting them together (twisting) is used.

This method requires, in order to ensure its reliability and safety, one of the following additional operations (clause 2.1.21 of the EIC):

• soldering;
• crimping;
• welding;
• or crimp.

Soldering

This is not the simplest method in terms of technological execution, but it gives a very high reliability of the wire connection. For soldering you need:

1. Select the required solder (depending on the material of the wire).
2. Rosin is suitable for flux (substances designed to remove oxides from the surface of wires and improve solder spreading).
3. Prepare a soldering iron (turn it on and warm it up).
4. Sand the stripped wires with sandpaper.
5. Twist the switched wires (50-70 mm long) together using pliers. It is necessary to twist the wires tightly, but not too much, so as not to deform them before breaking.
6. Heat up the place of twisting the wires with a soldering iron (or a gas burner if the wires are thick).
7. Apply flux to the wires throughout the twist.
8. Completely cover the stranded wires with hot solder.
9. Let the solder on the wires cool down and check the reliability and completeness of the soldering .
10. The connection is securely insulated with electrical tape or in another way.

Crimping

For crimping, you will need a tool with which you can reliably crimp the junction of the wires and a special sleeve-tip. A sleeve-tip (or GAO - an aluminum sleeve for crimping) is an aluminum tube with or without lubrication. As a crimping tool, you can use manual press tongs, pliers, a mechanical or hydraulic press. Next, the following steps are performed:

1. From the ends of the wires, the insulation is completely removed by 20-40 mm from the edge (depending on the length of the prepared HAO).
2. The metal of the wires is polished to a shine with sandpaper.
3. Wires with pliers are tightly, but neatly twisted together.
4. A GAO twist that is suitable for the cross-sectional diameter is selected (preferably with lubrication, otherwise you will have to apply quartz-vaseline paste yourself).
5. The sleeve is put on the twisting of wires.
6. GAO is completely crimped by the prepared tool.
7. The quality of the compression is checked by the complete absence of the possibility of movement of the wire cores in the sleeve.
8. The connection is securely insulated with electrical tape or other method. .

Welding

Welding is the fusion of metal wires into one core under the influence of an electric arc. The method is very effective, but requires a special welding machine and is more suitable for professionals than for independent execution.

crimping

Crimping is the most accessible method of amplifying and isolating switching in terms of technological design, and no less effective than the previous ones.

Crimping of twisted wires is carried out using terminal blocks, PPE caps (connecting insulating clamps), or WAGO clamps.

Terminal blocks allow you to switch copper and aluminum wires, since they do not have direct contact. These products exist for various wire sizes and are easy to use. Switching in such blocks is possible in two ways:

1. Each wire has its own screw.
2. Each wire through the entire terminal under both screws.

PPE caps with force are wound onto the twisting of the wires. Under the influence of forces, a conical spring made of metal inside the cap moves apart and reliably compresses the wire strands. To prevent oxidation when switching aluminum wires, an anti-oxidation paste is added inside.

Clamps WAGO compress the wires under the force of the spring. They do not have screws, they also allow you to connect copper and aluminum wires, they can be used for wires of various stiffness and multicore. WAGO clamps differ in the number of applications (single-use and reusable) and in the number of simultaneously switched cores (up to 8). Using these clamps is very simple, you need:

• if the clip is disposable, just insert the wire into the socket until it locks;
• if the clamp is reusable, insert the wire into the socket, and then snap the latch.

Protecting electrical wiring inside walls

Wiring inside walls, with insufficient protection against operational risks, can cause a short circuit or even a fire. If the wiring is old, then it is better to replace it, but new wiring should be done in compliance with all measures to ensure the protection of the electrical cable.

Currently, there is a sufficient choice of means that provide reliable protection for electrical wiring inside walls. For these purposes, the following products are used:

1. Metal pipes.
2. Plastic pipes.
3. Corrugated plastic pipes.
4. Metal armored sleeve.

Metal and plastic pipes

For protection, it is allowed to use steel as well as plastic pipes. metal pipe(if it is not special) you must first prepare, for which:

• cut off the necessary workpiece;
• if necessary, bend the pipe with a pipe bender based on: - more than 6 diameters - with hidden laying; - more than 10 diameters - when laying in concrete;
• remove burrs on the ends of the pipe.

Wiring in steel and plastic pipes is well protected from mechanical damage and adverse conditions environment. If only protection against mechanical influences is assumed, then the pipeline is not sealed. To protect against adverse external environmental influences, the pipeline is also sealed. For sealing, seals are used at the junctions of pipes with each other and at the inlets and outlets of junction boxes and electrical consumers.

When mounting electrical wiring in pipes made of metal and plastic, it is necessary to take into account the possibility (if necessary) of removing the wires for their replacement or maintenance. To do this, if there are two or more pipeline bends, the distance between the boxes must be chosen no more than 5 m, and the straight sections should be no more than 10 m long.

The minimum cross-sections of the strands of copper wires laid in plastic and steel pipes make up - 1.0 mm², and aluminum - 2.0 mm².

Corrugated plastic pipes

Corrugated plastic pipe made of plastic (“corrugated”) with self-extinguishing, non-combustible material certified according to current regulations fire safety NPB 246-97. Such a product provides sufficient protection of electrical wiring from mechanical influences and reliably protects fire hazardous elements of the material and wall decoration located near the wire from fire.

This type of protection is easy to install and not very expensive. "Corrugation" can be laid both inside concrete and stone walls, and inside frame walls made of wood.

Metal armored sleeve

This method of protecting the electrical cable is suitable where there may be significant mechanical and thermal effects on the electrical wiring.

The metal armored sleeve is a flexible corrugated hose with a plastic tube inside.

Wiring in such a product can be made both leaky and sealed with the help of seals.

Even 15 - 20 years ago, the load on the power grid was relatively small, but today there are a large number of household appliances provoked an increase in loads at times. Old wires are far from always able to withstand heavy loads and over time there is a need to replace them. Laying electrical wiring in a house or apartment is a matter that requires certain knowledge and skills from the master. First of all, this concerns knowledge of the rules for wiring electrical wiring, the ability to read and create wiring diagrams, as well as skills in electrical installation. Of course, you can do the wiring with your own hands, but for this you must adhere to the rules and recommendations below.

Wiring Rules

All construction activities and Construction Materials strictly regulated by a set of rules and requirements - SNiP and GOST. As for the installation of electrical wiring and everything related to electricity, you should pay attention to the Rules for the Arrangement of Electrical Installations (abbreviated PUE). This document prescribes what and how to do when working with electrical equipment. And if we want to lay electrical wiring, then we will need to study it, especially the part that relates to the installation and selection of electrical equipment. The following are the basic rules that should be followed when installing electrical wiring in a house or apartment:

• key electrical components such as distribution boxes, meters, sockets and switches should be easily accessible;
• installation of switches is carried out at a height of 60 - 150 cm from the floor. The switches themselves are located in places where opened door does not prevent access to them. This means that if the door opens to the right, the switch is on the left side and vice versa. The wire to the switches is laid from top to bottom;
• sockets are recommended to be installed at a height of 50 - 80 cm from the floor. This approach is dictated by flood safety. Also, sockets are installed at a distance of more than 50 cm from gas and electric stoves, as well as heating radiators, pipes and other grounded objects. The wire to the sockets is laid from the bottom up;
• the number of sockets in the room must correspond to 1 pc. for 6 m2. The kitchen is an exception. It is equipped with as many sockets as necessary to connect household appliances. Installation of sockets in the toilet is prohibited. For sockets in the bathroom outside, a separate transformer is equipped;
• wiring inside or outside the walls is carried out only vertically or horizontally, and the installation location is displayed on the wiring plan;
• wires are laid at a certain distance from pipes, ceilings and other things. For horizontal, a distance of 5 - 10 cm from the floor beams and cornices and 15 cm from the ceiling is required. From the floor, the height is 15 - 20 cm. Vertical wires are placed at a distance of more than 10 cm from the edge of the door or window opening. The distance from the gas pipes must be at least 40 cm;
• when laying external or hidden wiring, it is necessary to ensure that it does not come into contact with the metal parts of building structures;
• when laying several parallel wires, the distance between them must be at least 3 mm or each wire must be hidden in a protective box or corrugation;
• wiring and connection of wires is carried out inside special junction boxes. Connection points are carefully isolated. The connection of copper and aluminum wire to each other is strictly prohibited;
• grounding and neutral wires are bolted to the devices.

Project and wiring diagram

Work on laying electrical wiring begins with the creation of a project and a wiring diagram. This document is the basis for future house wiring. Creating a project and a scheme is quite a serious matter and it is better to entrust it to experienced professionals. The reason is simple - the safety of those living in a house or apartment depends on it. Project creation services will cost a certain amount, but it's worth it.

Those who are used to doing everything with their own hands will have to, adhering to the rules described above, as well as having studied the basics of electrics, independently make a drawing and calculations for the loads on the network. There are no particular difficulties in this, especially if there is at least some understanding of what electric current is, and what are the consequences of careless handling of it. The first thing you need is conventions. They are shown in the photo below:

Using them, we make a drawing of the apartment and outline lighting points, installation locations for switches and sockets. How many and where they are installed is described above in the rules. The main task of such a scheme is to indicate the installation location of devices and wires. When creating a wiring diagram, it is important to think in advance where, how much and what household appliances will be.

The next step in creating the circuit will be the wiring to the connection points on the circuit. At this point it is necessary to dwell in more detail. The reason is the type of wiring and connection. There are several such types - parallel, serial and mixed. The latter is the most attractive due to the economical use of materials and maximum efficiency. To facilitate the laying of wires, all connection points are divided into several groups:

• lighting of the kitchen, corridor and living rooms;
• toilet and bathroom lighting;
• power supply of sockets in living rooms and corridors;
• power supply for kitchen sockets;
• power supply socket for electric stove.

The above example is just one of many lighting group options. The main thing to understand is that if you group the connection points, the amount of materials used is reduced and the circuit itself is simplified.

Important! To simplify the wiring to the sockets, the wires can be laid under the floor. Wires for overhead lighting are laid inside the floor slabs. These two methods are good to use if you do not want to ditch the walls. In the diagram, such wiring is marked with a dotted line.

Also in the wiring project, the calculation of the estimated current strength in the network and the materials used are indicated. The calculation is performed according to the formula:

I=P/U;

where P is the total power of all devices used (Watts), U is the mains voltage (Volts).

For example, a 2 kW kettle, 10 60 W bulbs, a 1 kW microwave, a 400 W refrigerator. Current strength 220 volts. As a result (2000+(10x60)+1000+400)/220=16.5 Amps.

In practice, the current strength in the network for modern apartments rarely exceeds 25 A. Based on this, all materials are selected. First of all, this concerns the cross section of the wiring. To facilitate the selection, the table below shows the main parameters of the wire and cable:

The table shows the extremely accurate values, and since the current strength can fluctuate quite often, a small margin is required for the wire or cable itself. Therefore, all wiring in an apartment or house is recommended to be made of the following materials:

• wire VVG-5 * 6 (five cores and a cross section of 6 mm2) is used in houses with a three-phase power supply to connect the lighting shield to the main shield;
• wire VVG-2 * 6 (two cores and a cross section of 6 mm2) is used in houses with a two-phase power supply to connect the lighting shield to the main shield;
• wire VVG-3 * 2.5 (three cores and a cross section of 2.5 mm2) is used for most of the wiring from the lighting panel to junction boxes and from them to sockets;
• wire VVG-3 * 1.5 (three cores and a cross section of 1.5 mm2) is used for wiring from junction boxes to lighting points and switches;
• wire VVG-3 * 4 (three cores and a cross section of 4 mm2) is used for electric stoves.

To find out the exact length of the wire, you will have to run a little around the house with a tape measure, and add another 3-4 meters of stock to the result. All wires are connected to the lighting panel, which is installed at the entrance. Protection circuit breakers are mounted in the shield. Usually this is an RCD for 16 A and 20 A. The former are used for lighting and switches, the latter for sockets. For an electric stove, a separate RCD is installed at 32 A, but if the power of the stove exceeds 7 kW, then an RCD is installed at 63 A.

Now you need to calculate how many sockets and distribution boxes you need. Everything is pretty simple here. Just look at the diagram and make a simple calculation. In addition to the materials described above, various consumables will be required, such as electrical tape and PPE caps for connecting wires, as well as pipes, cable channels or boxes for electrical wiring, socket boxes.

Installation of electrical wiring

There is nothing super complicated in the work on the installation of electrical wiring. The main thing during installation is to follow the safety rules and follow the instructions. All work can be done alone. From the installation tool, you will need a tester, a puncher or a grinder, a drill or a screwdriver, wire cutters, pliers and a Phillips and slotted screwdriver. A laser level would be helpful. Since without it it is quite difficult to make vertical and horizontal markings.

Important! When carrying out repairs with the replacement of wiring in an old house or apartment with hidden wiring, you must first find and, if necessary, remove the old wires. For these purposes, a wiring sensor is used.

Marking and preparation of channels for electrical wiring

We start installation with markup. To do this, using a marker or pencil, we put a mark on the wall where the wire will be laid. At the same time, we observe the rules for placing wires. The next step is to mark the places for the installation of lighting fixtures, sockets and switches and a lighting panel.

Important! In new houses, a special niche is provided for the lighting shield. In the old ones, such a shield is simply hung on the wall.

Having finished with the markup, we proceed either to the installation of wiring open way, or to chasing walls for hidden wiring. First, with the help of a perforator and a special nozzle of the crown, holes are cut out for the installation of sockets, switches and junction boxes. For the wires themselves, strobes are made using a grinder or a puncher. In any case, there will be a lot of dust and dirt. The depth of the groove of the strobe should be about 20 mm, and the width should be such that all wires fit freely into the strobe.

As for the ceiling, there are several options for resolving the issue with the placement and fixing of the wiring. The first - if the ceiling is suspended or suspended, then all the wiring is simply fixed to the ceiling. The second - a shallow strobe is made for wiring. The third - the wiring is hidden in the ceiling. The first two options are extremely simple to implement. But for the third, some explanations will have to be made. In panel houses, ceilings with internal voids are used, it is enough to make two holes and stretch the wires inside the ceiling.

Having finished with the gating, we proceed to the last stage of preparation for wiring. Wires to bring them into the room must be pulled through the walls. Therefore, you will have to punch holes with a puncher. Usually such holes are made in the corner of the premises. We also make a hole for the wire plant from the switchboard to the lighting panel. Having finished the wall chasing, we begin the installation.

Installation of open wiring

We begin installation with the installation of a lighting shield. If a special niche was created for it, then we place it there, if not, then we simply hang it on the wall. We install an RCD inside the shield. Their number depends on the number of lighting groups. The shield assembled and ready for connection looks like this: in the upper part there are zero terminals, grounding terminals at the bottom, automatic machines are installed between the terminals.

Now we start the wire VVG-5 * 6 or VVG-2 * 6 inside. From the side of the switchboard, the electric wiring is connected by an electrician, so for now we will leave it without connection. Inside the lighting panel, the input wire is connected as follows: we connect the blue wire to zero, the white wire to the upper contact of the RCD, and connect the yellow wire with a green stripe to ground. RCD automata are interconnected in series at the top using a jumper from a white wire. Now let's move on to the wiring in an open way.

On the lines outlined earlier, we fix boxes or cable channels for electrical wiring. Often, with open wiring, they try to place the cable channels themselves near the plinth, or vice versa, almost under the very ceiling. We fix the wiring box with self-tapping screws in increments of 50 cm. We make the first and last hole in the box at a distance of 5 - 10 cm from the edge. To do this, we drill holes in the wall with a puncher, hammer the dowel inside and fix the cable channel with self-tapping screws.

One more distinctive feature exposed wiring are sockets, switches and distribution boxes. All of them are hung on the wall, instead of being walled in. Therefore, the next step is to install them in place. It is enough to attach them to the wall, mark the places for fasteners, drill holes and fix them in place.

Next, we proceed to the wiring. We start by laying the main line and from the sockets to the lighting panel. As already noted, we use the VVG-3 * 2.5 wire for this. For convenience, we start from the connection point towards the shield. We hang a label on the end of the wire indicating what kind of wire and where it comes from. Next, we lay the wires VVG-3 * 1.5 from switches and lighting fixtures to junction boxes.

Inside the junction boxes, we connect the wires using PPE or carefully insulate them. Inside the lighting panel, the main wire VVG-3 * 2.5 is connected as follows: brown or red wire - phase, connected to the bottom of the RCD, blue - zero, connected to the zero bus at the top, yellow with a green stripe - ground to the bus at the bottom. With the help of a tester, we “ring” all the wires in order to eliminate possible errors. If everything is in order, we call an electrician and connect to the switchboard.

Installation of hidden electrical wiring

Performed concealed wiring simple enough. A significant difference from the open one is only in the way the wires are hidden from the eyes. The rest of the steps are almost the same. First, we install a lighting shield and RCDs, after which we start and connect the input cable from the side of the switchboard. We also leave it unconnected. This will be done by an electrician. Next, we install distribution boxes and socket boxes inside the niches made.

Now let's move on to the wiring. We are the first to lay the main line from the VVG-3 * 2.5 wire. If it was planned, then we lay the wires to the sockets in the floor. To do this, we put the VVG-3 * 2.5 wire into a pipe for electrical wiring or a special corrugation and lay it to the point where the wire is output to the sockets. There we place the wire inside the strobe and put it into the socket. The next step will be laying the VVG-3 * 1.5 wire from switches and lighting points to junction boxes, where they are connected to the main wire. We isolate all connections with PPE or electrical tape.

At the end, we “ring” the entire network with the help of a tester for possible errors and connect it to the lighting panel. The connection method is similar to that described for open wiring. Upon completion, we close the strobes with gypsum putty and invite an electrician to connect it to the switchboard.

Laying electricians in a house or apartment for an experienced craftsman is quite an easy task. But for those who are not well versed in electrics, you should take the help of experienced professionals from start to finish. This, of course, will cost money, but this way you can protect yourself from mistakes that can lead to a fire.

Faulty electrical wiring poses a strong danger to people and structures, because in most cases it is a source of fire. In the event of a fire from electrical wiring, the first thing they try to find out is who is to blame for this and at whose expense it is necessary to carry out restoration work. Next, we will consider the main causes of wiring fires and ways to protect against this. dangerous situation.

Causes of ignition of electrical wiring

In case of neglect of safety measures in the room, a fire may occur. Also, electric shock can lead to serious consequences. We will consider the most popular causes of ignition of the wiring below.

Technical difficulites. It is important to monitor the condition of all network wiring, as well as their connections. This includes the main and switchboard, because it is in such places that the main cable lines are supplied, and various protective devices are installed. All devices must be in working order. Back-up protection should be installed in the switchboards in advance, which can be used in case of some dangerous situation (for example, protection against short circuit). Basically, ignition of electrical wiring is possible due to poor contact, therefore, special attention should be paid to the junctions of the electrical wiring. For safety and reliability during operation, it must be installed in an apartment, in production or in workshops, especially where there is high humidity.

Smoothly moving from one reason to another, it should be noted that often the ignition of the wiring in the apartment occurs due to the fact that incorrectly selected circuit breakers. The fact is that the purpose of the machine in the shield is to instantly work in case of a short circuit or overload in the network. So, with regard to overload, when choosing a circuit breaker, you need to pay attention to the fact that the nominal value of the machine corresponds to the cross section of the wiring to protect which it is installed. Otherwise, when overloaded, the cable in the wall will start to melt and may catch fire, and the machine will not work, or it will work when it happens, which may be too late and still cause a fire in the house or apartment.

Incorrect or unsafe operation. Each device has a load limit. The cause of the fire may be the connection of various splitters or extension cords to the same outlet. Damaged plugs or appliance cords are a great danger. If a short time after turning on some electrical appliance in the network, the plug or splitter heats up, this means that there is a problem in the contact connections.

Lighting group fault. Lighting devices eventually become the cause of the outbreak. For example, it is necessary to protect an incandescent lamp from splashes, and a switch from moisture.

Technical failures include connection of aluminum wire with copper. Even if everything is connected correctly and the neutral wires are connected with a special bar, a fire in the wiring can occur. For such connections, a bar made of brass material is not suitable, because over time it oxidizes and aluminum with brass heats up, which consequently leads to a fire. If such a compound was inside a combustible plastic shield, then the consequences would be even worse, because instead of preventing combustion, it begins to melt and support the hearth. It is possible to connect aluminum with copper, if it is impossible to perform electrical wiring in any other way. However, the connection must be made either through special or using special sleeves.

Another reason is poor quality and old sockets. After all, the plug of the electrical appliance itself must fit tightly into the outlet. If the plug gets hot or sparks, change the socket immediately. It is better to pay a little more, but buy a quality outlet. Although they may look the same, in cheap models, the plastic heats up and lights up, and the contacts do not have compression springs. About that, we told in a separate article.

The next reason is old aluminum wiring. In old multi-storey buildings, switchboards are located in the stairwell. Often they are in a very neglected state, so there is a particular risk of fire. Also, in most old houses, the electrical wiring has never changed, which means that it has already outlived its usefulness, the insulation becomes unusable, and, accordingly, does not protect against a short circuit in the wall. To this we can add that now much more electrical appliances are used than before, therefore the load increases on the old wires, which can be aluminum and withstand small loads.

Today there is a problem low-quality electrical goods. These products do not withstand the load declared by the manufacturer. It is often necessary to troubleshoot a house or apartment that has only recently been rewired. After about a couple of years, the cable insulation cracks and begins to crumble, and this inevitably leads to a fire.

Visually, some of the causes of a wiring fire are discussed in the video:

Fire protection measures

Should apply various measures protection to keep wiring in good condition, such as running it under plaster rather than flammable building materials. As for the shields, it is better to choose them from metal or non-combustible plastic - this will serve as protection against the spread of fire. We have covered this in detail in a separate article.

It is also important to do at least once a year: look at all wire connections in sockets, switches, junction boxes and in the electrical panel itself. Timely detection of poor contact and melted wires is one of the effective ways fire protection.

If the wiring is old, be sure to replace it with a new one at the next repair. Cracked insulation, old sockets designed for a lower current load, plugs in the shield. All this can lead to a fire at any moment. If it is not yet possible to spend money on, be sure to install machines and RCDs in the shield. They will save you from a fire at the right time. Also desirable in wooden houses put a fire protection RCD at 100 or 300 mA on the input, as an additional measure of protection.

The fire RCD is described in detail in the video:

In addition to all this, it is important to know and in no case repeat, which we wrote about separately. For example, a poorly made twist can cause a short circuit and further ignition of the electrical wiring. Therefore, twists do not need to be done at all.

And of course, if the apartment smells of burnt wiring, and you yourself are not able to find and fix the problem, be sure to call an electrician, after turning off the machines in the shield.

How and how to extinguish a burning electrical wiring

To extinguish burning wiring, it is necessary to use special effective fire extinguishing agents. It is necessary to understand well what to do, how to extinguish, what should be the procedure and which fire extinguisher is applicable when extinguishing wiring.

The first thing you need to know is that if the wiring is energized, it is strictly forbidden to extinguish it with water. Due to the fact that water is an ideal conductor of current, the one who pours water will definitely receive an electric shock. If it is possible to turn off the mains power, then you can use sand, water or a fire extinguisher. However, in the case where it is impossible to turn off the power, only a class E fire extinguisher is used. The class is marked on the fire extinguisher body.

To extinguish burning electrical wiring, carbon dioxide, aerosol and powder extinguishing agents are used. They are used to extinguish under voltage up to 1000 volts. If the voltage is higher, de-energize the network. Under no circumstances should an air-foam or chemical-foam fire extinguisher be used for live fires. In more detail about that, we told in a separate article.

So we examined why there is a fire in the wiring in the apartment and how to protect yourself from this dangerous situation. We hope that the information provided was useful for you and made you think about the implementation of a number of recommendations!

You probably don't know:

The structural imperfection of electrical networks is the main cause of sudden voltage surges. It is impossible to predict the time of the next drop. The only thing we can do to prevent unpleasant consequences is to secure electrical consumers in our home in advance. In this article, we will tell you how and how to protect the network of an apartment and a house.

What will save you from the jumpdressing up

Surge protection is possible with different types protective devices. We'll talk about the most common ones. These are voltage control relays (RN) and household stabilizers.

Surge Protection Relay

Protecting the house from power surges with the help of PH is recommended in cases where the mains voltage is stable and its noticeable surges are rare. RN is a device capable of reading the parameters of an electric current and breaking electrical circuit at the moment when the indicators go beyond the specified range. After the indicators in the general network are normalized, the device will automatically close the circuit and resume power to consumers. The function of resuming power after a specified period of time (with a delay) built into the 220v home voltage relay helps to extend the life of some household appliances, refrigerators, etc.

PH have small dimensions, relatively low cost and good performance. The disadvantages of PH include their inability to smooth out fluctuations in electrical energy. For maximum protection of all consumers, you will need to install several devices at once.

RN protects the network only from unacceptable power surges and is not designed to protect against short circuits (this function is performed by circuit breakers).

Modern models of launch vehicles are of three types:

1. Stationary relay built into the electrical panel of a house or apartment.

2. Relay for individual protection of one consumer.

3. Relay for individual protection of several consumers.

If everything is practically clear with the operation of relays of the second and third types, then the first type has a more complex design, and its installation requires certain knowledge. Such devices are mounted at the entrance to the room, so protection against power surges in the network of all home electrical equipment is performed.

PH selection

When choosing a relay to protect the home network, it is enough to know the rating of the electric current that is able to pass through the input circuit breaker. If, for example, the capacity of the circuit breaker is 25A (which corresponds to a power consumption of 5.5 kW), then the performance of the RH should be a step higher - 32A (7 kW). If the switch is designed for 32A, then the relay must withstand a current of 40 - 50A.

loa FORUMHOUSE user

For such a case, I took a 40 A relay, with an introductory machine 25/32 (it is the first one, but the setting will increase).

Some people choose the brand of RN based on the total power consumption. This is not entirely correct. After all, a relay capable of withstanding a current of 32A can safely operate both at a load of 7 kW and at much higher power consumption. Only in the second case, it is necessary to integrate a special magnetic contactor into the operating circuit of the PH. But more on that in the next section.

PH installation

The standard scheme for installing the RH in the switchboard is shown in the figure. This is the simplest surge protection.

Work on the installation of the PH should be carried out only with the input switch turned off!

As you can see, everything is simple: the control relay is installed immediately after the electric meter and connected to the phase wire, through which the entire house is supplied with electricity. When jumping outside the set (adjustable) range, the relay disconnects the external power supply from the internal wiring, and protection against power surges is performed in the apartment and in the house.

PH, mounted in the panel of the shield, occupies a minimum of space on the DIN rail.

If the power of consumers of the home network gives a total of 7 kW or more, manufacturers strongly recommend that an additional electromagnetic contactor be built into the operating circuit of the LV. Although, a reliable contactor in general scheme will never become an extra detail, see the following comment:

Vitichek FORUMHOUSE user

It is better to put a contactor to any relay, although the manufacturers write that the PH can withstand high currents. The contactor has large contacts and less resistance.

This device helps to unload the contacts of the RN, independently disconnecting power line from the general network of household consumers. The control relay, at the moment of unacceptable overvoltage, only gives a command to turn off. After that, the electromagnetic coil of the contactor disconnects the power contacts connecting the external and internal networks. The connection diagram in this case will be as follows:

Voltage surge protection system.

Surge protection 220v

In order for the RH to benefit its owner, its operating parameters (voltage tolerance limits and power-up delay time) must be properly adjusted. If one pH is used in the working circuit, then the limits of permissible values ​​\u200b\u200bshould be set, focusing on the characteristics of household appliances that are sensitive to drops. The most sensitive and expensive equipment is audio and video equipment. The range of permissible voltage values ​​​​for it is 200 - 230V.

Permissible voltage deviation from nominal values ​​in domestic energy networks is 10% (198…242V). In the case of frequent operation of the PH, these indicators can be taken as a basis by adjusting the relay. However, sensitive consumer electronics in this case are recommended to be protected using portable stabilizers of low price.

DenBak FORUMHOUSE user

Nobody says that it is necessary to turn off at plus or minus 15V. There is a range of maximum permissible deviations of 10%, which most devices must withstand. You need to set, based on this, approximately 190V-250V. Although, with our state of networks, especially in the private sector, everything is expected. So sensible caution can't hurt.

In order to provide the best possible protection for all consumers, you should use wiring diagram with multiple relays. Working scheme protection, including several RH, allows you to divide consumers into groups - in accordance with their sensitivity to overvoltage:

1. The first group includes audio and video equipment (permissible voltage values ​​​​- 200 - 230V);
2. The second category includes household appliances equipped with an electric motor: refrigerators, air conditioners, washing machines, etc. (permissible values ​​​​- 190 - 235V);
3. The third group is simple heating devices and lighting (permissible values ​​​​- 170 - 250V).

Each group of consumers is connected to its own pH. In such a scheme, the operating parameters of each relay are configured individually.

Network protection against overvoltage and surges.

The power-on delay time should be in accordance with the performance requirements of household appliances. For some refrigerators, for example, the recommended delay is 10 minutes.

Protection of a three-phase network using PH

If the power supply to your house is carried out through a three-phase system, then it is advisable to install a separate control relay for each phase.

Three-phase voltage relays are designed exclusively for the protection of the relevant equipment (electric motor, etc.). If such a relay is installed at the input to the dwelling, then a voltage imbalance in one of the phases leads to a de-energization of all single-phase consumers.

Surge Protectors

If there are constant power surges in your house, then the PH will work several times a day, de-energizing the entire house. Therefore, in such cases, a less simple, more expensive, but also more practical way to protect home electronics is recommended. It consists in the use of stabilizers - devices that smooth out voltage surges in the external network, giving out a constant indicator of 220V at the output.

According to the type of connection, two types of stabilizers are distinguished: local (which are connected to the outlet, protecting from one to several consumers) and stationary (connected to the input power cable and protecting all consumers of the home network). Local stabilizers should be used to protect the most sensitive household appliances. They can be operated in conjunction with a stationary launcher.
Stationary stabilizers are complex devices that not only smooth out voltage fluctuations in the entire household network, but are also able to save expensive equipment by automatically turning off the power to consumers when overloaded and reaching critical values.

It is highly recommended to install stationary stabilizers if the voltage value goes beyond 205 ... 235V several times a day (this can be determined using an ordinary tester).

If the light in the house is constantly blinking, and the voltage goes beyond 195 ... 245V, then it is forbidden to use household electrical appliances without a stabilizer!

How to choose a stabilizer

The stabilizer should be chosen based on the total power of domestic consumers. The device must have a decent power reserve.

Backup alarm switch

The power outage signaling circuit, Fig. 1, not only emits an audible signal when the power is turned off, but can also turn on the backup power source by means of an electromagnetic relay. In this signaling circuit, the same intermittent signal generator is used, but plus to it, the circuit is supplemented with an electromagnetic relay, which is connected by one of the contacts between the diodes VD1 and VD2.

Fig.1

Power outage signaling device

In the presence of voltage in the mains, the contacts of this relay are attracted. When the current fails, the capacitor C6 discharges sharply, as a result of which the voltage on the relay drops, it opens the contacts. The presence of the VD2 diode in the circuit prevents the rapid discharge of capacitors C1 and C2 through the relay winding.

Automatic protection schemes for a three-phase motor in case of phase failure

Three-phase electric motors, if one of the phases is accidentally disconnected, quickly overheat and fail if they are not disconnected from the network in time. For this purpose, developed various systems automatic protective shutdown devices, however, they are either complex or not sensitive enough, fig. 2

Fig.2

Protective devices can be divided into relay and diode-transistor ones. Relay, unlike diode-transistor ones, are easier to manufacture.
An additional relay P with normally open contacts P1 has been introduced into the conventional system for starting a three-phase motor. If there is voltage in the three-phase network, the winding of the additional relay P is constantly energized and the contacts P1 are closed. When the "Start" button is pressed, a current passes through the electromagnet winding of the MP magnetic starter and the electric motor is connected to a three-phase network by the MP1 contact system.
If wire A is accidentally disconnected from the network, relay P will be de-energized, contacts P1 will open, disconnecting the winding of the magnetic starter from the network, which will disconnect the motor from the network by the MP1 contact system. When the wires B to C are disconnected from the network, the winding of the magnetic starter is de-energized directly. Relay is used as an additional relay P alternating current type MKU-48.

current protection

household electrical devices- washing machines, electric meat grinders, electric fireplaces - as a rule, they operate on 220 V alternating current. In the event of a breakdown of the insulation on the metal case of such an installation, voltage may be dangerous to human life. To protect against defeat electric shock household appliances should be grounded, especially if they are used in hazardous areas.

Bathrooms are an increased risk when washing clothes in washing machine. Moreover, the possibility of electric shock increases significantly if the floor in the room is conductive, the humidity of the air exceeds 75%.

Most outlets installed in apartments have a third, grounding wire, as a rule, absent. Therefore, where it is not present, as a protective measure against possible electric shock in the event of a current leakage or insulation breakdown, it is recommended to install automatic disconnecting devices on the case Fig.3.

Fig.3

Consumer of electrical energy, containing a winding L 1, connect to the network using a two-pole non-polar connector (ordinary plugs and sockets). From a rectifier assembled according to a diode bridge circuit VD 1-VD 4, the relay K1 is powered, which has two NC contact pairs K1.1 and K1.2. A thyristor is connected in series with the common winding of the relay VS 1. Its control electrode is connected through a resistor R 2 with transistor collector VT 1. The emitter of the transistor is connected to the positive pole of the rectifier, and the base through a high-resistance resistor R 1 is connected to the metal case of the electrical appliance.

The device works as follows. When a working electrical appliance is connected to the network, the relay winding does not receive power, since the thyristor is closed. Through the opening contacts K1.1 and K1.2, the current passes through the consumer winding L 1. In the event of an insulation breakdown, the current flows from the phase or “neutral” wire through one of the rectifier diodes, the “emitter-base” junction of the transistor, the resistor R 1, the metal casing of the electrical appliance, and then through the insulation breakdown site and part of the winding L 1 enters the wire with a voltage of opposite polarity. As a result, the transistor opens, and current begins to flow in its collector circuit. Through a resistor R 2 it goes to the control electrode of the thyristor and then to the "minus" of the rectifier. The relay is activated and opens its contact pairs, disconnecting the appliance from the network. At the same time, through the transition "emitter - base" VT 1 current does not pass, and the transistor closes. However, the thyristor continues to remain open, since the relay winding plays the role of a smoothing filter, and through VS 1 a direct current flows, the value of which is sufficient to keep the thyristor in the open state. Therefore, after the machine is triggered, the relay remains activated until the appliance is disconnected from the network.

The protective device turns off the electrical installation in case of insulation breakdown at any point of the consumer winding L 1. It also works at the slightest leakage current.

Resistor R 1 should have a resistance of 1.5 - 2 Mohm. If you touch a grounded metal object with one hand and the chassis with the other household appliance equipped with this protective device, then less than 1 mA passes through a person, which is quite safe. Automatic protection immediately works and disconnects the appliance from the network.

To check the operation of the device, the body of the electrical appliance is briefly connected with a piece of wire to a grounded structure - the relay should work.

Karachev N.

Power on equipment protection

Fig.4

In power supplies of powerful equipment based on transistors and microcircuits, capacitors are usually used in power filters, the capacitance of which exceeds 10,000 microfarads. Transient processes that occur when such equipment is turned on (in particular, the charging of these capacitors) can lead to its failure. For this reason, devices have recently been introduced into power supplies that limit the current in the primary winding of the network transformer at the first moment after turning on the equipment and thereby prevent undesirable effects.

A possible implementation of such a device is shown in Figure 4. It consists of limiting resistors and a node that closes these resistors after a certain time.

The current surge when the equipment is turned on up to a value of 5A is limited by resistors R4-R 7. The use of several resistors here is due only to design considerations. They can be replaced with a single resistor with a resistance of 40 ohms and a dissipation power of at least 20 W, or with another series-parallel combination of resistors that provide the same resistance and dissipation power.

The choice of the value of the limiting resistor is a solution to a controversial problem. On the one hand, it is desirable to have a large resistance, since overloads in the power supply circuits when the device is turned on and the required power dissipation of this resistor are reduced, but on the other hand, the resistance should not be very large so that the second current surge that occurs when the limiting resistor is closed is not greater than the initial inrush current when the device is turned on. The parameters of the limiting resistor given here are close to optimal for equipment that consumes 150 ... 200 W of power from the network.

When the equipment is turned on, the process of charging capacitors C2 and C3 simultaneously begins. When the voltage on them reaches the trigger voltage of relay K1 and it works, it will close the resistors with its contacts R4-R 7 and thereby restore the normal operation of the power source. The turn-on delay time of the equipment depends primarily on the capacitance of capacitors C2 and C3, the resistance of the resistor R 3, the operation voltage of the relay K1 and is a fraction of a second.

A relay with a response voltage of 24 V was used in the device. It must have contacts that ensure the inclusion of network equipment (220 V and a current of several amperes) with which this protective device will be used.

The bridge used in the original design is designed for an operating voltage of 250 V and a current of 1.5 A. Capacitors C3 and C4 can be replaced with one with a capacity of 1000 microfarads.

Obvod zpozneneho startu.

"Amaterske Radio", 1997,

A7-8, s.24

Open-phase motor protection

The open-phase motor protection device shown in Figure 5 responds to interruptions in the supply of voltage to a three-phase motor from any of the three phases.

Fig.5

Push button S 1 voltage is applied to the coil of the KM1 magnetic starter, which includes the M1 electric motor. Reliable operation of the starter with its coil rated for 380 V AC voltage, with a smaller amplitude pulsating voltage, is ensured by a significant constant component of the latter.

Simultaneously with the actuation of the starter, the voltage is supplied to the anode and the control electrode of the thyristor VS 1. Now the capacitor C1 is recharged through a periodically opening thyristor, the voltage on it remains sufficient to keep the KM1 starter in the triggered state. In the event of a power failure in any of the phases, the thyristor stops opening, the capacitor quickly discharges and the starter disconnects the motor from the network.

Yakovlev V.

Shostka, Ukraine

Emergency switch

Power outages are a lot of trouble. It is especially bad that at the moment the voltage is applied, there can be very dangerous surges, which, at best, cause TV processor failures or DVD - the player by transferring them to the on mode, and in the worst case, they damage the power supply.

Fig.6

Figure 6 shows a diagram of an alarm relay, which disconnects the equipment from the network when the power supply is turned off. And the power supply to the equipment does not occur simultaneously with the resumption of power supply, but only after the user presses the button S1.

The scheme is based on the old KUTs-1 relay from systems remote control TVs of the "USCT" type.

Unit for protecting electrical equipment in case of accidents in the power grid

Many, at least once in their lives, found themselves in a situation where, instead of a single-phase voltage of 220 V AC, a two-phase 380 V suddenly began to flow into apartments. If such an event was not noticed in the first seconds and the apartment wiring does not have surge protection devices, then All home appliances are out of order. The very fact that in a normal situation the potential of the "neutral" wire relative to the "ground" does not exceed a few volts, and in case of an accident in three-phase networks of the final power supply it reaches 220 V or more, makes it possible to make a simple device for protecting equipment, the circuit in Fig. 7.

Fig.7

If 220 V plus or minus 30 percent pass through the electric meter, the coil of the powerful electromagnetic relay K1 is de-energized. The rated supply voltage is supplied to the loads through the free-closed relay contacts.

Let's say an accident happened and as a result the "neutral wire" turned out to be phase. Since the "Ground" input of the protective device assembled according to scheme 1 has a reliable electrical connection with the soil, a voltage of 160 ... 250 V AC will appear on the relay coil, which leads to opening of its contacts and de-energizing the loads. Zener diodes connected in back-to-back series VD1, VD 2 eliminate the possible slight buzzing of the relay during normal power supply. Resistor R 1 limits the current through the coil of relay K1. neon glow lamp HL 1 lights up in case of an accident. Capacitor C1 prevents the occurrence of an arc when the relay contacts open.

Kashkarov A.