How to fix damage to hidden wiring. Wiring Repair: Troubleshooting

If the wiring is properly designed and installed in accordance with the requirements of the Electrical Installation Code, malfunctions rarely occur in it.

However, if the power supply to any part of the circuit is interrupted, the problem should be found and corrected. In this article, we will tell you how to find a break in hidden wiring in the wall.

Let's see how to find a malfunction in the wiring? Malfunctions occur due to incorrect or careless installation, violation of the integrity of the insulation, wire breakage, poor contact between circuit elements or network overload. The fault is indicated by:

• No zero;
• Absence ;
• Lack of phase and zero at the same time;
• spark;
• Short circuit.

Indirectly, a malfunction is indicated by too frequent operation of protective automation.

Classification

Most often, malfunctions occur at the junctions of the wires at, at the points of connection to the contacts of automatic machines or switches of the lighting network. Such malfunctions belong to the first class, they account for more than half of the cases of electrical network failures. All of them are relatively easy to detect and eliminate.

Second class of faults- damage to hidden wiring during repairs during drilling, chiselling and other work related to the need to penetrate into the thickness concrete structure. Due to repairs, a screw or a nail may be driven into the wiring. In such cases, there is a high probability of a short circuit in the wall.

Minor damage to the insulation does not always show up right away, it can take months or even years for the problem to show up.

Third class- a wire break directly in the wall without outside intervention. This is a rather rare occurrence and the share of third-class faults accounts for about 20% of cases of malfunctions. A break can occur due to severe wear of the wiring made of aluminum wire, overloads in the network or a malfunction.

The cause of the break may also be violations of the installation technology., for example, twisted connections, mechanical damage insulation or incorrect calculation of the wire section for a specific connection group.

The most “harmless” consequence of a wire break is the lack of voltage at a single connection point, the entire connection group, or the whole apartment. In the event of a break in the neutral conductor, in addition to de-energizing a single branch or an apartment as a whole there is a threat of overloading the healthy part of the network. Sparking wiring or a short circuit can lead to more serious consequences, including a fire.

Search Procedure

To search for a break you will need:

• Locator or other device for searching for a break in hidden wiring in the wall;
• Screwdriver;
• pliers;
• Knife with insulated handle;
• Insulating tape.

First of all, you need to define an emergency connection group. If you have, there is nothing complicated about it. If there is a phase on the damaged outlet, then turning the machines on and off, you can find the wire you are looking for. The presence of a phase is checked by an indicator. The connection group in which the problem has been identified should be completely disconnected from the machine, disconnecting all cable cores.

After that, you need to sequentially ring all the connections, starting from the cable in the shield until you find the place where the sockets are connected by one core. If there is access to junction boxes, they must be opened. If there are no problems inside, the damaged core is called from the connection.

If the boxes are not available or the wiring is done without them, you need to remove the sockets along the entire length of the damaged area and ring through them. Most often, problems occur in the first outlet, since it accounts for the maximum load. If the damage is still not found, then it is inside the wall.

looking in the wall

Most fast way detection of a phase conductor break - search with locator. The device consists of a receiver and a generator. The generator is connected to a damaged wire: the negative terminal of the device is attached to the whole core and grounded at the access shield, the positive terminal is connected to the damaged core.

After that, the generator is turned on and into the whole core, impulses are supplied from it. The locator receiver must be moved along the wiring route.

The receiver responds to pulses from the generator and emits an audible signal. Above the gap, the sound signal stops.

To clarify the localization of the gap, the generator is connected to the other end of the damaged area and the search procedure is repeated. Ultimately, the audio signal disappears at the previously detected point.

Counter search for the accident site- a necessary condition, since the accuracy of determining gaps is usually about 10-15 cm. The more accurately the location of the damage is detected, the less work will have to be done.

Sometimes problems arise with the neutral wire. In such cases, when checking the contacts on the indicator screwdriver, a faint glow is observed when it comes into contact with the zero contact. People who do not have experience in troubleshooting the electrical network interpret this as "two phases". When checking with a multimeter, any voltage can be fixed on the contact in the range from 0 to 220 V.

It should be remembered that when zero breaks, a faulty outlet can shock because it has a phase. The search for a zero break is performed in exactly the same way as the search for damage to a phase conductor.

If there is no locator at hand, you can find the place of the cliff using a radio receiver. The receiver is tuned to any channel of the medium wave range, an electrical appliance of small power, for example, an electric razor, is plugged into the emergency outlet. The included receiver is slowly moved along the route.

The integrity of the wire is indicated by noise, crackling or other interference.. Over damage, the nature of the interference changes or they disappear altogether. What other devices can determine the breakage of hidden wiring, find out from this.

In the place of violation of the integrity of the cable, the strobe is opened with a perforator or with a hammer.

Troubleshooting

If the problem occurs in new wiring, the ends of the wire must be connected. The connection is made as follows:

In some cases, the damaged area must be completely replaced by pulling it through with a pulling device.

The procedure for repairing a damaged neutral conductor is slightly different from repairing a phase. The neutral wire is disconnected from the bus and a phase wire is attached to it.. After that, all other actions are performed in the same way as when eliminating a phase break.

Prevention

Detect and eliminate hidden defects wiring is extremely difficult, but some troubles can be avoided. Before embarking on any repair work associated with penetration into the thickness of the walls, you should find hidden wiring using a locator or any other available device.

If we are talking about old-style wiring made of aluminum wire, it is advisable to replace it completely as soon as possible.

The main measure to prevent power failures is proper design and strict adherence to installation rules.

Hello, friends!

In this article I will talk about one problem, which for some reason, many are silent. But the problem exists and it is serious enough to talk about it. We are talking about possible damage to the wiring during the installation of a stretch ceiling. Agree, this is worth talking about.

The article will be long, so enough prefaces, let's get down to business.

The essence of the problem lies in the fact that there is no strict standard for the placement of electrical wiring lines in apartments. There are some recommendations, but who is interested in them ... As a result, the lines are laid everywhere in different ways. Their location can be different even in the same entrance in different apartments.

Therefore, when drilling walls for mounting a stretch ceiling, there is always a chance of damaging the wires.

Here are a couple of examples of how hidden wiring can be located:

As you can see, cables can go anywhere. Many builders (and not only them) do not care deeply about what will happen after them. As they say, after me at least a flood.

Apartment owners can feel relatively calm in panel houses. In them, as a rule, the wiring is laid in the seams between the plates. In brick houses, the cable is laid under a layer of plaster and can be anywhere. Moreover, it doesn't matter an old house or new building.

Recently, I was called as an electrician to an apartment to deal with one malfunction. The bottom line is this: suddenly a differential machine went off in this apartment, which cuts off electricity in the event of a current leakage or short circuit. It was not possible to turn it on again, because. it immediately worked again.

In a conversation with the owners of the apartment, I found out that a few months ago they installed stretch ceilings and at the same time fell into hidden wiring several times. Ceiling installers somehow repaired the damage and everything seemed to start working.

After examining and testing the whole thing, it became clear that one of two things happened:

1) After the "specialists" who installed stretch ceilings damaged the cable, they restored it with some snot. Everything seems to be working. And then, over time, these snot burned and problems began ...

2) When the "specialists" drilled the walls, they slightly damaged the core of the cable (not completely killed, but only damaged). The machine worked. These guys turned it on - everything works. And let's continue to drill (time, time, you need to earn money). Since the cross section of the damaged core was greatly reduced, it burned out from the load ...

As a result, we have a catastrophic situation: a 1-room apartment filled with furniture, infant, 1 working socket for the whole apartment, and even the house is not gasified. And those guys who did the ceilings have already disappeared, there is no one to ask.

The place of damage is unknown - in order to find it, it is necessary to remove the stretch ceilings, unscrew the profile, gouge the holes (the furniture gets in the way, but there is nowhere to put it, it's a pity for the new wallpaper, plus a baby-baby).

Complete, sorry for the expression, ass...

As you can see, the consequences can be (and really are) very bad. And now let's talk about how to avoid such situations. First, about what needs to be done if, when drilling the walls, they nevertheless damaged the hidden electrical wiring.

A small digression. The main rule of the installer stretch ceilings: when drilling walls, a chandelier or lamp must be turned on. If it goes out during drilling, it will immediately become clear that the lighting line has been damaged. Damage to the outlet line is easier to see - the punch stops working.

So, if the wiring is damaged, you need to do the following:

• carefully open the damaged area so that there is access to the damaged wires
• strip wires from insulation by 10-11 mm
• connect the wires using repair inserts made of wire and self-clamping terminal blocks (I recommend using proven German Wago terminal blocks)

It looks something like this:

In this case, be sure to follow a few rules:

Firstly, if the native wiring is aluminum, then it is imperative to use terminal blocks with a special paste that improves contact and prevents aluminum from oxidizing.

Secondly, the cross section of the repair wires should not be less than the native ones. Copper wire with a cross section of 2.5 sq. mm. suitable for lighting and outlet lines.

Thirdly, if a heavily loaded line of large cross section (from 4 sq. mm) is damaged, for example, for oven, instantaneous water heater or hob, then in this case the terminal blocks cannot be used - they will not withstand high current. Such lines should go without a break from the machine to the end user. In extreme cases, if nothing else remains, you can connect this line by twisting with welding.

A few more photos of broken electrical wiring and its restoration:

The following photo clearly shows how unpredictably a cable can go in plaster. This is a brand new building that has just been completed. As you can see, the line goes at random.

Why do I recommend using Wago terminal blocks for repairs? Now a uniform orgy is going on in the network about the use of these terminal blocks. No matter what they write. I will not rewrite all this nonsense, I will say one thing: with correct installation these terminals are the best way detachable connection. In addition, their use will eliminate the need to gouge a large section of the wall at the site of damage.

These terminal blocks are designed for an operating current of 24 amperes, which is more than 5 kilowatts - an excellent indicator.

How to convert amps to kilowatts and vice versa? Very simple:

Amps to Watts - Amps (current) times Volts (voltage) = Watts (power).

24 (Amps) * 220 (Volts) = 5280 Watts (5.28 kW)

Watts to Amps - Watts (power) divided by Volts (voltage) = Amps (current).

1500 (Watts) / 220 (Volts) = 6.82 (Amps)

A gentleman's set of terminal blocks that a self-respecting installer should always have with him

Some technical information about Vago terminal blocks:

Wago terminal blocks for aluminum wires

We figured out how to properly repair damaged electrical wiring. And how to avoid damage to the wires when installing a stretch ceiling? Let's figure it out.

The first thing that comes to many minds is to use a hidden wiring detector to determine the places where electrical lines and do not drill in these places. Naturally, the same thought came into my head many years ago when I first pierced the wire. There are several types of such devices on the market.

Over the years I have bought and tried many different detectors, both cheap and expensive. The result - none of them coped with the task. All of them, to one degree or another, revealed shortcomings: a large error and false positives. As they say, flop.

After trying a bunch of devices and talking with colleagues, including those from other regions, it became clear that there is only one reliable detector - a perforator...

Is there really no way to 100% avoid damaging the wiring, you ask. I hasten to please - of course, there are such ways. There are at least two of them.

The first way is to change the wiring in advance. If you are doing a complete apartment renovation, then you have a great opportunity to change the old wiring to a new one. It is best to put it on the ceiling, and on the walls make only strictly vertical drops to sockets and switches. You can do it on the walls, just do not forget to carefully photograph and save all this. More information about electrical work can be found on the website http://elektro.site/na potolke

Method two - when installing stretch ceilings, use a ceiling mount. With this method, the profile for stretch ceilings (baguette) is attached not to the wall, but to the ceiling. This is usually done through timber or thick plywood. By the way, the same method is used to bypass those places where it is impossible to gain a foothold in the wall.

Of course, ceiling mounting will require additional costs, but you can be 100% sure that your electrical wiring is safe.

That's all for me. I hope this article was helpful to you

But yes, if everything is done correctly, it is necessary to periodically carry out at least once every few years Maintenance and checking all contacts and connections of electrical wires or cables.

Often, electrical wiring requires repair as a result of its improper operation. Periodically, there is a need to replace electrical wiring in a city apartment. In any case, during a malfunction occurs:

In order to avoid problems with the electrical network of your home, you need to know the causes of damage to it. Let's look at the types of faults in electrical wiring, indicating their causes.

Types and causes of electrical faults.

1. Wire insulation damage- accidental, with inept installation or over time from the old age of the wiring. Due to insulation failure, current leakage to earth or short circuits occur. Attention if, due to old age, the insulation from electrical wires begins to crumble - there is a high risk of fire and electrical injury. There is only one way out - a complete replacement of the electrical wiring in an apartment or house.
2. Damage to the integrity of the electrically conductive core as a result of accidental breakdown while driving nails or drilling holes in the wall. The wire often breaks in places where it is repeatedly bent in one place in distribution or mounting boxes or socket boxes designed for installing switches and sockets in them. Often the wires leading to the chandelier or lamp from the ceiling are broken.
3. Damage electrical cables due to malfunction or incorrectly selected circuit breakers or plugs in the electrical panel. Any section of the conductor is designed for a certain limitation on the current load. For example, the most common aluminum wires at home with a cross section of 2.5 square meters. mm. and copper - 1.5 square millimeters - allow a maximum continuous current load of not more than 16 amperes. For example, we connected washing machine with a power of 4 kilowatts or a current consumption above 20 A, respectively, a 16 ampere machine will knock out and you will have to replace it with a 25 ampere one. But this is not an option, because in this case the integrity of the electrical wires or cables will be damaged due to their overheating when operating at extreme loads.
   The only way out is to replace the power line a larger cable from the consumer to the electrical panel. Attention, often old machines do not always work properly and provide effective protection home wiring.
4. Faulty household appliances or appliances. Often the reason for the operation of protection (machines) are faulty electrical appliances. As a result of insulation breakdown on a metal case or the occurrence of short circuit or current overloads inside these devices. It is important to disconnect them from the socket and do not use them again - take them in for repair or replace them.
5. No or poor contact in places where electrical wires are connected to lamps, chandeliers, sockets, switches or directly to other electrical appliances. The wire must be well clamped and completely come into contact with the bare part without insulation. be careful and do not pinch the insulation part. In particular advanced cases the contact burns out, the socket housing is destroyed, the insulation and the cores themselves are damaged. Always watch and tighten all electrical wiring contacts. Sometimes twisted wires in junction boxes that are installed under the ceiling burn out. Periodically check and tighten the twists, but do not use electrical tape for insulation, but only

Electrical wiring damage, although infrequent, does happen, and any owner in his house or apartment should be able to find the causes and place of damage. In order to help you in this simple matter, this article was written.

In it, we will look at troubleshooting methods, the most likely damage and, of course, how to eliminate them.

The reasons for the short circuit of the electrical wiring are quite diverse, but most of them are associated with its improper operation and non-compliance with the rules during installation.

We list only the most common causes of damage:

• The first and most common is wiring aging. Like everything in our world, wires are not eternal. They are subject to oxidation, which changes their physicochemical properties. At the same time, not only the material of the wires, but also the insulation is subject to aging. This is especially pronounced in aluminum wires.
• Second, but no less an important factor is wire overload. The reason for this may be either the wrong choice of the section of the wiring (see), or the connection of electrical equipment for which it is not intended. Due to overload, the wire overheats, which destroys its insulation and changes its physical and chemical properties.

• Also, any instruction will indicate to you that incorrect connection of wires leads to their accelerated aging. After all, contact connections are the weak point of any electrical wiring, and they must be made in accordance with clause 2.1.21 of the PUE. This paragraph allows only welding, soldering and screw or bolt clamping methods to be used for connecting wires.
• Well, in the last place in our article is human activity. Due to flooding, intentional or accidental damage to the wire insulation, mechanical stress, a huge amount of damage occurs.

Finding the location of wiring damage

Finding the location of the damage will greatly facilitate the wiring plan, if you have one. This will not only significantly reduce the search area, but also eliminate unnecessary actions in the undamaged section of the power grid. But usually there is no such plan and you have to search in the hope of observing generally accepted norms and rules.

Determination of damage

Before proceeding with the search for the place of damage, we should determine the nature of the damage. We will consider damage to a single-phase 220V network, since it is used in most houses and apartments.

For a three-phase circuit, there can be much more damage options, and only determining the nature of the damage will require much more effort.

So:

• To determine the nature of the damage, we consider two main options. The outlet is not working and the lighting is not working. For normal operation of these devices, it is necessary that a phase and neutral wire be connected to them. If they do not work, then one of the wires is not suitable and we need to determine which one.

• To further determine the location and nature of the damage, we need a two-pole voltage indicator. With it, we check the presence of a phase in the outlet. If there is damage in the lighting network, then we check the presence of a phase directly on the lamp or the place where the ceiling is connected.

Note! When checking the presence of a phase at the connection point of the ceiling or chandelier, the lighting switch must be turned on. If the phase is present, then open the switch and make sure that it is gone. If the phase is still present, then the connection of your lighting network does not comply with the PUE standards. This will greatly complicate the further search with your own hands.

• If the phase is present, then most likely we have a break in the neutral wire. This is much worse, because it is more difficult to determine it. In order to accurately verify the breakage of the neutral wire, two options can be used. Both of them can only be used with precautions and only by people who at least know the basics of electrical engineering. Otherwise, it is better not to perform this check.

So:

• Option number one. We find the zero contact on the nearest outlet. We connect a wire of sufficient length to this contact. We check the presence of a circuit between this wire and the zero contact of a non-working outlet or lighting network.
• Option two. V junction box damaged section after removing the voltage, turn off the phase wire of the damaged section. It should be insulated. In its place, we connect the neutral wire of the damaged area. We apply voltage and check the presence of a phase on the contact, which used to be zero. The absence of a phase is a sure sign of a break. After making sure of this, we restore the previous scheme.

Finding the location of damage in the event of a break

Having determined the nature of the damage, you can proceed directly to the search for its location. In more than 50% of cases, the site of damage is one of the contact connections.

After all, this is the weakest point. Therefore, we begin the search by inspecting the contact connections of the socket, switch or ceiling.

• Using this method, we will not only exclude one of possible causes, but also significantly narrow the search area. So by checking the contact connections, you can tell exactly which of the sections is losing zero or phase.
• Now the fun begins - the exact determination of the location of the damage. If you are using public method laying the wire, then a simple visual inspection of the wire in this area in 90% of cases will reveal the problem. Otherwise, you can replace the entire wire.
• If you have hidden wiring, then everything is a little more complicated. To search, you will need a wiring plan, at least an approximate one, and a special device for finding damage. But the cost of such a device is quite high. Some suggest creating your own device to search for a damaged element. But personally, I use a much simpler way.
• This will require a non-contact voltage indicator. The price of this device is not high, and indeed it greatly facilitates the work. This pointer is powered by electromagnetic field, which is around any live wire.
• If the wire is not laid under a very thick layer of plaster, then usually a non-contact pointer is enough. When you bring it to a wire that is under voltage, it begins to glow or make sounds, or both. You simply move the pointer along the line of possible wire laying until the indication disappears.
• If the indication is gone, then at this point you check that you simply did not lose the wire or that it did not turn. If everything is correct, then this point is your place of damage.

Note! In order not to make a mistake, check that there is no socket or switch in the adjacent room. In addition, before proceeding with the repair of damage, check everything a few more times.

• But, you say, what about the place of damage to the neutral wire. It is not an indicator to determine. Yes, it won't. Therefore, the neutral wire should be made phase, as we did when checking the integrity of the neutral wire.

Finding the location of damage in case of a short circuit

Separately, we will consider the question of how to find the place of damage during a short circuit. Indeed, with this damage, it is not possible to apply voltage to the damaged area.

When voltage is applied, the machine turns off or the plugs burn out:

• In order to exclude a short circuit, we should get rid of it. A short circuit is a connection of non-insulated phase and neutral wires. To rule this out, disable one of them.
• To simplify further search, the neutral wire is usually turned off. He is isolated and taken aside. After all, when you turn on the machine that feeds the damaged section of the network, it will be energized.

Note! During the execution of these operations, no electrical appliances should be powered from the sockets or the lighting network of this group. All of them must be removed from the sockets, otherwise it may damage them.

• Now apply voltage to the damaged section of the circuit. If there are no other short circuits, then the machine should not turn off. Otherwise, it is necessary to look for a wire touching grounded parts or a short circuit with a neutral wire of another group.
• If the machine has not turned off, then we perform a further search, as in the case with a broken phase wire. If a short circuit occurs with the wires going to the socket or switch burning off, you can easily identify the damage.
• You can check if the wires are burnt out or not by simply checking for the presence of a phase in the socket or switch in the damaged area. If there is a phase, then this indicates that at least one wire has not burned out.

• In this case, the search for the site of damage is extremely complicated and it is almost impossible to perform it at home. Therefore, it will be easier to either pull out the damaged area, or install a completely new wiring.

Repair of the damaged area

Repairing a damaged area is quite simple (see). Although ideally a new wire should be laid, temporary repairs can be made to this section as well. To do this, it is important to use a wire with a cross section not less than the existing one and from the same material.

So:

• First of all, we will have to remove the layer of plaster, under which the wiring is hidden. This should be done carefully so as not to further damage it.
• We make sure that we correctly identified the location of the damage by the presence of a break or traces of a short circuit.
• We cut the damaged wire and connect a small insert from the wire of the same material to it. Connection is best done by soldering or pressing. This will significantly reduce the depth of the required niche for the subsequent plastering of the wire.

• As insulation, it is best to use heat shrink, which will be much easier to put on and which, again, will save space.
• After repair, perform a functional test of your network by applying voltage and switching on the load. If possible, give a larger load and check that there is no increased heat at the joints. If everything is fine, you can plaster a niche with a wire.
• Re-energizing and putting into operation is best done after the plaster has dried.

Conclusion

As you can see, finding the location of wiring damage and troubleshooting is not such a difficult task. The main thing is to observe safety measures and have a minimum set of knowledge.

After all, there are videos that are best example what happens to those who, not understanding electricity, try to fix it.

Yandex.Direct

Of all possible problems with electricity, perhaps the most unpleasant are problems with wiring. They happen rarely and therefore always unexpectedly. Such an event is all the more unpleasant because the repair of an outlet or table lamp will take ten minutes and can wait until you have free time, while wiring requires attention here and now and repairs will take a lot of time. If you are a radio amateur, then in the second part there are diagrams.

The fact is that aluminum wire, which is not resistant to kink, could be used for wiring; the insulation could be damaged by careless work of electricians and subsequently the wire could not withstand the current overload. The result may be a short circuit, you will recognize it by the triggered safety plugs. Perhaps the wire will simply burn out quietly somewhere in the wall and half of the apartment will suddenly turn out to be without light.
V modern apartments all wiring is hidden, laid in grooves dug in the wall, and covered with a thick layer of plaster on top, then whitewashing or wallpaper (paint, Wall panels, tapestry, etc.). Thus, the minute work available to anyone - to twist the two ends of the wire and wrap them with electrical tape - is overgrown with a mass of annoying obstacles. Repairing hidden electrical wiring will require the skill of a plasterer-painter, the appropriate tools and time.
You'll be lucky if a short in a hidden wiring (for example, due to a broken wire insulation) can be determined without destroying half of the wall between the two junction boxes. But the hands really sink when, without any noise and lighting effects, the voltage in several outlets simply disappears and the light goes out.
You have already checked the presence of voltage at the input to the apartment. Plugs are in good order. Well, if the light remains somewhere in the apartment, it means that the gap search zone is shrinking. On the other hand, this situation does not leave any hope for some other cause of the malfunction.
So, humble yourself - you have to expose the hidden wiring, look for the place where the wire breaks, and then re-plaster and glue the wallpaper. However, knowing some of the rules by which, hopefully, the wiring was laid in your apartment, you can calculate the place of the gap at least approximately. Apply your analytical skills.
First, find the last branch box where there is voltage on one of the strands of each two-wire wire (checked with a voltage indicator). If the box covers are hidden by wallpaper, they are easy to find by tapping. This the starting point searches.
Secondly, the directions of the wires must be determined by the shortest path for their wiring; sockets, switches and lights serve as milestones along the wiring path. Knowing where the wire runs in the wall, you can minimize losses, but wiring is not always done on the basis of elementary logic, in addition, the layout always allows you to calculate this shortest path.
How to avoid repeated repairs? It turns out that there is still a way to get by with little blood when looking for a gap! This will require a simple device that is best assembled or ordered in advance before the thunder strikes.
Operating principle - registration electric field live conductor.

The device consists of a four-stage bass amplifier with a gain of about 3000-5000, a rectifier, a key stage and an audio frequency generator of 900-1600 Hz, is powered by two 3336L batteries connected in series and consumes a current of 5-8 mA. A voltage with a frequency of 50 Hz, induced by a current-carrying conductor in antenna A, is amplified by a low-frequency amplifier assembled on transistors T1 - T4, and rectified by diode D1.

A rectified negative voltage of the order of 0.2-0.4 V is supplied to the base of the transistor T5 of the key stage and unlocks it.

At this time, the blocking oscillator, assembled on the transistor T6, begins to generate audio frequency oscillations. These vibrations will be heard in the headphones that the generator is loaded with. All parts and transistors 1 of the device, except for switch V1, batteries, G1 sockets and telephones, are placed on a getinax board 120 × 72 mm in size.
The device board, batteries, sockets and power switch are located inside and on the side walls of a metal case with dimensions of 150x78x45 mm. Antenna A is a sheet of copper foil measuring 130×65 mm. It is fixed in the window of the housing cover on an insulating getinax plate measuring 146 × 74 mm. The static current gain (None) of the transistors installed in the device should be in the order of 35-50.
Transformer Tp1 is wound on a core 1115×6, winding I contains 1500 turns of PEV wire 0, 1, winding II - 600 turns of the same wire. You can check the operability of the blocking generator if you temporarily short-circuit the collector with the emitter of the transistor T5 with a wire jumper. With the correct connection of the terminals of the winding I of the transformer Tpl, the generator starts working immediately. Otherwise, you need to swap them.
To establish a key stage, a voltage of 0.2-0.4 V in negative polarity must be applied to the base of the transistor T5. It can be removed from the divider, made up of fixed resistors with a resistance of 5, 1 kOhm and 150 Ohm, included in a common power circuit. When this voltage is applied to the key stage, the supply voltage of the low-frequency blocking generator should be 7 ~ 8 V. Establishing a low-frequency amplifier is reduced to selecting the resistance of the resistor R3, on which the modes of transistors T2 - T4 depend. The use of a variable resistor R2 in the circuit allows you to adjust the sensitivity of the device.
The hidden wiring route or the place of its damage is determined as follows.
To the circuit, the breakage or route of which needs to be determined, connect the phase of the 220/380 V power supply. Headphones are connected to the device and the power is turned on. When the power is turned on, the tone of the generator should be heard for some time in the headphones. This indicates the normal operation of the device. Antenna A is directed towards the intended location of the wire and, by the presence of a tone in the head phones, its route is traced. In the event of a wire break, the tone stops at a distance of 5-7 cm from the break.
A normally adjusted device allows you to register the presence of a voltage of 50 Hz at a distance of 6~8 cm from the conductor. In all cases, the metal housing of the instrument must be in contact with the operator's hands.
In addition to determining the laying of the wiring and its breaks, using the device, you can determine the location of the short circuit of the hidden wiring. To do this, an electromagnetic sensor is connected to the input of the device through connector G1, which allows registering the magnetic field of conductors with alternating current.
The electromagnetic sensor is an open magnetic circuit made of W-shaped transformer iron with a coil containing 3000-6000 turns of PEV-2 wire with a cross section of 0.1-0.12 mm. P112 core (sh9, sh10, sh14, etc. can be used), the thickness of the set is 12-15 mm. The sensor is mounted on a rod and connected to the device with a flexible shielded cable 1.5-2 m long. The location of the short circuit of the hidden wiring is determined as follows.
A pair of wires, the place of the short circuit of which must be determined, is connected to a special step-down transformer

The sensor is brought to the place where the wires are laid with the open side of the magnetic circuit and, by the presence of a signal in the headphones, their route is traced. Behind the short circuit, there is no magnetic field of the wires, the signal disappears.
The Tp1 transformer is wound on a Sh16 core, the package thickness is 32 mm. Winding I contains 1560 turns of wire PEV-2 0.14 mm, winding II - 8 turns of wire PEV 2 0.8 mm. Capacitor C1 is included in the primary winding circuit to limit the current in the secondary circuit when searching for a short circuit in short sections (5-8 m).
Another device that allows you to fix the presence of voltage in the network in a non-contact way can be used to indicate the route of hidden wiring.
The device responds to the electrical component of the electromagnetic field, and its operation does not depend on the presence or absence of current in the wiring.
The voltage signaling device is powered by a 9 V battery. The current consumption in the indication mode is 15 mA, in the absence of a signal - 5 mA. Dimensions 100x50x30 mm, weight 250g.
A schematic diagram of a non-contact signaling device is shown in Figure 5.
It consists of the following units: an antenna, an electrometric amplifier, a discriminator and pulse expansion unit, an audible alarm unit, and a device health monitoring unit. The electrometric amplifier is made on an integrated circuit MS2 voltage follower with a field effect transistor at the input. Its sensitivity depends mainly on the resistance of the resistor R6, within a small range it can be adjusted by the resistor R5.
The discriminator and pulse expansion unit consists of a rectifier based on diodes D1 and D2 and a single vibrator based on transistors T1 and T2, the threshold of which is set by the DZ diode. The sound signaling unit is made according to the multivibrator circuit based on transistors T3 and T4. A miniature electromagnetic capsule Gr1 of the DEMSH or TM-2A type is included in the collector circuit of the transistor T4.
Schematic diagram of a non-contact voltage detector
The health monitoring unit is an asymmetric multivibrator on an MC1 integrated circuit, which generates short pulses with a repetition rate determined by the capacitance of the capacitor C1. These pulses once every 5-6 s through the capacitor C2 arrive at the An1 antenna and cause the device to operate. In this case, the signaling device emits a single sound signal with a duration of less than OD s, indicating that the device is in good condition. If the voltage indicator is inserted into electric field electrical installations, then an EMF will be induced in the antenna, which is fed to the input of the amplifier. From the output of the amplifier, the variable component of the current through the capacitor C3 enters the discriminator. If the signal level is less than the specified one, then the one-shot will not start.
With a decrease in the distance to parts of the electrical installation that are energized, it increases sharply. When the predetermined signal level is reached, the single vibrator starts and the sound signaling unit begins to generate a sound signal. All parts of the signaling device are mounted on printed circuit board and together with the battery are placed in a metal case with end walls made of insulating material. One of the end walls is made of foil getinax and is used as an antenna. The foil was removed from a part of the getinax surface, the dimensions of the antenna are specified when the device is adjusted. On the part of the end wall free of foil, two rows of holes about 1.5 mm in diameter were drilled for the sound channel of the acoustic chamber.
Figure 6 shows the design of the acoustic resonator chamber and the attachment of the electromagnetic capsule to it. The side wall of the detector housing is used as the other wall of the chamber. This camera is placed under the circuit board.
A button for turning on the device and a HI1 socket for connecting a charger are mounted in the second end wall. Establishing a voltage signaling device does not cause difficulties and comes down mainly to adjusting the response threshold according to the electric field strength.

The design of the acoustic resonator chamber with the G1 capsule attached to it.
First, check the current consumed in the absence of an audible signal. The current should not exceed 5-6 mA. After that, the collector and emitter of transistor T2 are short-circuited. This should generate an audible signal. In the absence of a health monitoring signal, the multivibrator on the MC1 chip is checked. In conclusion, the signaling device is tested, gradually bringing it closer to the distance allowed by safety regulations to the current-carrying wire. In this case, the device should work and give an audible signal.
A properly adjusted signaling device allows you to register an alternating voltage of 220/380 V at a distance of 5-10 cm. In this case, the metal case of the signaling device must be in contact with the operator's hand. If the triggering distance of the signaling device differs from the specified one, the sensitivity of the amplifier should be adjusted by selecting the resistance of the resistor R5. If the sensitivity of the signaling device is insufficient, the resistance of the resistor R5 should be reduced, if it is too high, it should be increased. If it is necessary to change the sensitivity of the signaling device over a wide range, you should select the resistance of the resistor R6 or change the size of the antenna.
When the damage location is established, you can try to replace the entire damaged wire without destroying the walls. If the hidden wiring was laid in special grooves, try to pull out the damaged piece of wire, using it to stretch a new one.
To do this, disconnect one end of the damaged section in the junction box. Access to the other end can be obtained by disassembling the first socket or switch after damage.
If this fails, then, knowing the location of the damage to the hidden wiring, you can limit yourself to point intervention without punching the wall along the entire length of the wiring route
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