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
Protection against voltage surges is possible using different types of 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 the electric current and breaking the 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 restoring 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 the 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 the introductory circuit breaker is able to pass through. If, for example, the capacity of the switch 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 PH. Although, a reliable contactor in the 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 PH contacts by independently disconnecting the 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 scheme, 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.
The permissible voltage deviation from the nominal values in domestic power 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 ensure the most reliable protection of all consumers, an electrical circuit with several relays should be used. The working protection scheme, which includes several RH, allows you to divide consumers into groups - in accordance with their sensitivity to overvoltage:
- The first group includes audio and video equipment (permissible voltage values - 200 - 230V);
- The second category includes household appliances equipped with an electric motor: refrigerators, air conditioners, washing machines, etc. (permissible values - 190 - 235V);
- 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.
Even 15 - 20 years ago, the load on the power grid was relatively small, but today the presence of a large number of household appliances has 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 building materials are 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 the open 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 ones, a distance of 5 - 10 cm from 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 the symbols. 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 most accurate values, and since the current 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 in an open way, or to the chasing of 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 top 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.
Another distinctive feature of open 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 below. 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
Hidden wiring is quite simple. 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 look at the main causes of wiring fires and how 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 rating 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, as a result, leads to a fire. If such a compound was inside a combustible plastic shield, then the consequences will 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
Various protective measures should be taken to keep the wiring in good condition, such as running it under plaster and not under 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 to protect against fire.
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. It is also desirable to install a fire RCD for 100 or 300 mA at the input in wooden houses, 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:
Backup alarm switch
The power outage alarm 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, various systems of automatic protective shutdown devices have been developed, 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. As an additional relay R, an AC relay of the MKU-48 type is used.
current protection
Household electrical appliances - washing machines, electric meat grinders, electric fireplaces - as a rule, operate on 220 V AC. In the event of an insulation breakdown on the metal case of such an installation, voltage may be dangerous to human life. To protect against electric shock, household appliances should be grounded, especially if they are used in areas with increased danger.
Bathrooms are an increased risk when washing clothes in a 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 does not exist, 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 case of a household appliance equipped with this protective device with the other, then a current of 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 power dissipation of at least 20 W, or with another series-parallel combination of resistors that provide the same resistance and power dissipation.
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 Fig. 5 responds to interruptions in the voltage supply to a three-phase motor of 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 circuit is based on the old KUTs-1 relay from the remote control systems of USST TVs.
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.
Light, heat, work of engineering and household equipment - everything is tied to electricity. Therefore, the level of comfort depends entirely on the uninterrupted and, importantly, safe operation of the electrical network. Any defect or mistake made during the installation of electrical equipment and electrical wiring can lead to sad consequences - fires or fires.
The topic of correct installation of electrical wiring for wooden houses is especially relevant. due to discrepancies in the interpretation of the PUE (Electrical Installation Rules) and the SP (Set of Rules), confusion and a lot of disputes arise. Therefore, in this article we will answer the following questions:
- What are the basic principles of wiring in a wooden house.
- How is electrical wiring installed in a wooden house in accordance with the rules of the PUE and SP.
- Technical features of the installation of hidden electrical wiring.
Proper wiring in a wooden house
Wood is a building material with a long history. Both small guest houses and large cottages are built from it. With all the advantages of both log and frame houses, which are based on wooden racks, many believe that such buildings have an increased fire hazard. But one important point is missing.
Regardless of what the house is built of - brick, aerated concrete, timber or logs, upholstered furniture, curtains, curtains, interior items, household appliances, etc. burn first of all. Those. - "stuffing" of the house, made of combustible materials.
In a stone house, the electrical wiring going from the switchboard to the consumers is mounted in fireproof material (the cable is laid in strobes, which are then sealed and plastered, etc.).
In this case, the developer faces a difficult choice - the wiring in a wooden house can be outdoor , the cable can be run inside the wooden walls or between the studs of the frame.
How to lay a cable in a wooden house.
Consider all these ways of laying wires in a wooden house. If in the first case the electrical wiring is visible, which affects the speed of detecting an emergency situation (cable overheating, etc.), then in the second case it is hidden behind the cladding or in a solid wood. Accordingly, what happens to the cable is not clear. Hence the developer's fears and doubts: “What if something happens to the electrical wiring? Will it light up or not?
Practice shows that the “weak” point in the electrical network is not the cable itself (we do not consider cases of gross violation of installation, the use of a cable with an underestimated section, on which a large load was “hung”, “twisting” on electrical tape on the route to splice the cable), but connection points - junction boxes, leads for connecting consumers, i.e. sockets, switches, etc.
Modern power cables, with the abbreviation VVGng, etc., do not support combustion.
There is constant debate about where it is safer to run the cable - outside or inside the walls, whether open wiring is acceptable in a wooden house. There is an opinion that if we lay the wiring along the wall, this will give us time to see and react to an emergency and make the right decision on how to proceed. Put out the fire or evacuate.
Simply put, to smell the smoke immediately, and not later, when the flame has already spread to the structural elements. If the wiring is mounted in the wall, even in a steel pipe, then this may not save you from a fire either.
Semik FORUMHOUSE User
I can refer to my experience as a firefighter and the experience of an electrician in an emergency gang. Steel pipes are more needed for mechanical protection of wiring from the "fool", the teeth of rats, which can even gnaw through a metal hose and damage the cable. I have seen more than once how a steel pipe, with wiring shorted inside, was red-hot. If this happens in a wooden wall, a fire is inevitable.
According to the user, the first thing to think about when installing electrical wiring is a competent calculation of all cable sections and the choice of electrical equipment for protection. That is, figuratively speaking, it makes no sense to install a 100 A circuit breaker on a wire with a cross section of 0.75 square meters. mm with a distance to the consumer in kilometers.
Hence, a safe electrical network is a balanced system, where each element, from circuit breakers to the cross section and length of the cable, as well as the end user, are matched to each other. Hoping that by stretching the cable through a metal pipe in a conditional wooden wall, we have already protected ourselves from fire is a delusion. The rules for laying cables in a wooden house are a rather vague thing, so far we have solved only part of a difficult task, which will be discussed below.
PUE and SP: standards and rules for installing electrical wiring in wooden and frame houses
We repeat once again that we have left outside the scope of this article the external wiring in cable channels. We also do not consider the so-called. retro wiring. This option, both in design and in terms of financial component, is not suitable for everyone.
Therefore, we set the task - it is necessary to install hidden electrical wiring in a wooden or frame house in a safe and regulated way.
What wire to use for a wooden house
It seems that everything is simple - you need to open the PUE (seventh edition of 07/08/2002) and read paragraph 7.1.38, which says:
Electrical networks laid behind impassable suspended ceilings and in partitions are considered as hidden electrical wiring, and they should be carried out: behind ceilings and in the voids of partitions made of combustible materials in metal pipes, having the ability to localize, and in closed boxes; behind ceilings and in partitions made of non-combustible materials - pipes and ducts made of non-combustible materials, as well as cables that do not spread combustion. It must be possible to replace wires and cables.
Now we are opening a document for frame builders, namely SP 31-105-2002 "Design and construction of energy-efficient single-family residential buildings with a wooden frame." We read paragraph 13.5.1:
Wiring should be arranged by passing cables (sheathed wires) through voids or spaces filled with insulation inside the walls and ceilings of the house, as well as through holes in the wooden elements of the frame of walls and ceilings. Pass such cables and wires through the structure of the house it is allowed to arrange without the use of bushings and tubes.
And paragraph 13.5.2:
For wiring sheathed insulated wires must be used or cables sheathed in flame retardant materials.
- A cable is two or more insulated conductors joined together and covered with insulation.
- A wire is a solid or stranded conductor with or without insulation.
Cable for wiring in a wooden house.
Accordingly: due to inconsistencies in the PUE with the joint venture and the vagueness of the wording in the PUE, many users have a question - how to properly install electrical wiring for combustible materials. As prescribed in the PUE - laying it in a steel pipe. Or as it is written in the joint venture - using a cable that does not spread combustion, without additional protective sheaths. On this basis, there is a lot of controversy.
Vitalik1985 FORUMHOUSE User
I think that laying cables in steel pipes- this is a redundant solution. The probability that the cable will break through is scanty, fires often occur due to a spark in the outlet. It is better to pay more attention to circuit breakers, connections, terminal box, switches, etc.
Danil117 FORUMHOUSE User
It must be done in such a way as to eliminate the very possibility of a wire fire. We choose the correct cable section, we select high-quality machines. That is, we do not hope that a steel pipe is a panacea for ignition and fire.
We will also consider opposing views.
Sollara FORUMHOUSE User
I think that wires for a wooden house should be in a metal pipe with localization ability. If a wire catches fire, it will burn inside. If it is shorted out, the arc will not burn through the pipe. We put metal junction boxes connected to the pipe.
A steel pipe for electrical wiring in a wooden house must be grounded.
Also interesting is the opinion of the user of the portal with the nickname Ivanov Kostya.
By laying the cable in a metal pipe, we solve two problems: we protect the cable from possible mechanical damage and we protect the tree from possible ignition of the cable.
Moreover, the first point is of key importance in relation to our construction conditions. Workers can, while mounting drywall or drilling something, pierce an unprotected cable with a self-tapping screw or a nail. The cable insulation can be damaged by the sharp edge of the metal profile. The cable can be gnawed (as an option) by rats or mice. In addition, the accumulation of wood dust during a spark or insulation breakdown can lead to a rapid spread of flames inside the walls.
It seems that such a solution is redundant, but in this way we protect the cable from force majeure, including the common situation: "forgot where the cable goes in the wall, hung a shelf / picture and damaged it."
Although, in order to avoid such situations, we do not lay the cable as we have to, but along strictly defined and marked cable routes, if necessary, taking photographs with an attached tape measure.
Is corrugation acceptable for electrical wiring in a wooden house
From the foregoing, it becomes clear that a part of FORUMHOUSE users believe that electric cable in wooden houses, with hidden wiring should be only in metal pipes. Let's emphasize - in steel pipes, and not in a metal hose, plastic self-extinguishing corrugation or steel corrugated pipe.
Corrugation for wires in a wooden house with hidden wiring is not good!
The short circuit arc (short circuit) burns through the steel corrugated pipe, and the plastic corrugation, due to its fragility, will not save the wiring from mechanical damage.
Others believe that it is a metal pipe for electrical wiring in a wooden house that is redundant and rely on foreign experience, which fully allows a cable in a log. In a classic frame using North American technology, an electric cable is pulled straight through wooden racks, in drilled technological holes, without corrugations, metal pipes, etc.
In the "Finnish" version of the frame, the electric cable is usually pulled in the inner layer of counter-insulation embedded in a wooden counter-lattice.
It seems that the technology is available for repetition, because it has stood the test of time, but, as you know, the essence lies in the details.
“Across the ocean”, grounding is necessarily done, and double - one goes to the street line, to the shield, the second is independent, connected either to copper pins driven into the ground or to the central water pipe. Plus, there is also a “zero” bus, and each line and electrical appliance (sockets, lamps, etc.) has its own independent grounding.
Roracotta Member of FORUMHOUSE
4 thick cables go to the house underground to the meter. Earth, zero and two phases. In addition to this ground on the cable, the central shield itself and the meter must be grounded by a separate ground or to a copper pipe when entering the house, or with two 16 mm copper pins 2 meters long, or a special copper plate buried in the ground to a depth of about a meter.
In a three-core "foreign" cable, the copper wire - "ground" goes without a braid. This ensures the operation of the RCD at the slightest damage to the insulation of the wires "zero" and "phase" throughout the route. While in our country the ground wire is insulated and provides protection only to end users.
Roracotta
In Canada, a rule has been introduced - all lines that feed sleeping rooms must be equipped with special automatic machines that are sensitive to sparks on the consumer (plug, socket, etc.). If a spark jumps somewhere, the machine knocks out. It's expensive, but it needs to be done.
And this is only part of the nuances that ensure electrical safety. Having decided to run a cable in a steel pipe in houses built of timber, we remember that a tree shrinks over time. Moreover, depending on the moisture content of the source material, this value can be significant. This means that it is necessary to think in advance how to ensure the necessary movement / independence of the steel pipe with the cable so that the beam does not “hang” on it in 2-3 years.
Condensation may form in the steel pipe, and moisture may enter the socket or junction box due to the slope of the route. Another "headache" is how to drive tracks in wooden houses of a large area. It is one thing to lay steel pipes in a wooden cottage of 100-150 sq. m, but a completely different task in complexity - in houses of 300-500 sq. m. In addition to increasing the estimate, special requirements are imposed on the qualifications of workers involved in the installation of electrical wiring in steel pipes.
Therefore, examples of the practical implementation of wiring cables in metal pipes are interesting.
Ivanov Kostya Member of FORUMHOUSE
I installed the electrical wiring in the wooden floor of the attic floor, in a steel square pipe 15x15 mm, with a VVGng cable with a section of 3x2.5. Turns and branching - a metal hose with a diameter of 20 mm, it is well pushed onto the pipe.
A square tube is more convenient to install than a round one.
Installation of wiring in a timber house
Also interested in wiring in a wooden house , performed by a user with a nickname Serg177. To do this, he bought a pipe 15x15 mm 300 meters long and a metal corrugation with a diameter of 2 cm, as well as staples (they are used to fasten corrugations with a diameter of 1.5 cm) to fix the pipes on the walls. Next, we carry out the installation of wiring, not forgetting to pre-clean the edges of the pipes from burrs!
