Nowadays, hidden wiring is used almost everywhere. The aesthetics of this type of electrical installation and its obvious advantages also have a negative side: hidden wires are very difficult to find when performing various repair work or in the event of malfunctions.
For specialists, such issues are practically not difficult, since each of them always has a device at hand that allows them to determine the true position of wires invisible to the eye. Home craftsmen cannot afford to acquire such a device: why spend often considerable sums of money if the product may be needed once or twice in a lifetime.
It is for such craftsmen, for such cases, that we decided to prepare this article, in which we have collected methods that allow us to accurately determine where hidden wiring is located.
The benefits of hidden wiring
Very often, when starting renovations in an apartment or house, a problem arises related to electrical wiring.
In very old homes you can still find the wires arranged externally, that is, they are simply attached to the wall.
In this case, tracking the location of the wiring will not be difficult, since it is visible.
But the practice of such wire laying has long been abandoned in favor of hidden installation, in which the cables are laid in special grooves and then sealed.
This is due to banal safety - an invisible wire cannot be accidentally damaged, but only if nothing is done to the wall.
“Folk” methods that don’t work
Search by compass
Some people mistakenly assume that if you hold a compass near the intended location with the cable, the magnetic needle will point to it. However, at home it is simply impossible to create magnetic induction of such strength that a compass will show the cable. At most, you can find out the location of the cardinal directions, or find the hidden treasures of Captain Flint :)
Search by smartphone
Some developers offer to turn your smartphone into a metal detector using their “miracle” applications. To do this, the phone just needs to have a magnetic sensor installed (we have one). iCHIP decided to take the plunge and check out popular metal detecting apps. We tested it in the same place as with a metal detector. Here's what happened:
As you can see, the readings of the “detector” in an empty space and in the place where the wiring actually passed through practically did not change, although the indicator should have become 0.02 - 0.03 mT. The same thing happened with other applications. From this we conclude that searching for wiring with a smartphone using applications is a rather dubious activity.
Perhaps you know other ways to detect wiring, or vice versa, that some methods are no longer relevant. Share them in the comments!
When might wiring location information be needed?
During renovations, drilling of walls is often required, and this is where hidden wiring becomes a problem, especially if the cables were laid a long time ago and there is simply no plan for electrifying the room.
To avoid damaging the wiring during work, you should know its location.
In general, such information may be required if:
- Redevelopment of the electrification of the premises (changing the location of sockets, switches, etc.);
- Redevelopment of the premises itself (making new openings - doors, windows);
- Problems with the wiring (break or short circuit);
- Interior improvements by hanging various appliances and furniture on the walls.
In case of replacement, it is not necessary to know the location of the wiring, since the old one will be removed anyway, so the house network is de-energized, and then the wires are simply pulled out of the grooves (they are usually plastered, and it is not difficult to pull them out), after which the circuit will be clearly visible.
And then it’s up to the owner to decide whether to lay the new cable in the old grooves or cut new ones.
Information about the location of wiring in walls is most often required when carrying out drilling work.
Next, we'll look at what you can do to determine where the cables run in the wall if there is no room layout.
Detector classification
Like any objects, devices designed to detect electrical wiring are divided into types.
Classification of hidden wiring detectors according to operating principle:
- Devices operating on the basis of electrostatic properties respond to fluctuations in the electric field;
- Electromagnetic devices respond to the magnetic components of electric current.
Both are suitable exclusively for wires that are located under voltage in a wall that does not contain moisture.
If the walls located next to the wires are damp or contain partitions made of steel, then the above devices are useless.
One of the simplest types of devices designed to identify wiring is a battery-powered indicator screwdriver. It is capable of combining both a detection alarm and a digital display at the same time.
If necessary, a metal detector notices electrical wiring that does not have load and voltage, and at the same time marks every metal inclusion that appears within its operation.
This device is extremely effective at the time of drilling, since it very accurately identifies obstacles that need to be avoided.
A combined device, which includes the advantages of both types, makes it possible to check and analyze all kinds of parameters. These include:
- the depth at which the object is placed;
- type of overlap;
- belonging of a metal product to any group.
Let's go back to the source
Many people know that according to the PUE, cables are laid only at right angles.
That is, the wiring is not placed along the shortest path, it should only run strictly horizontally or vertically, and the change in direction is made at an angle of 90 degrees.
This information is not enough to determine where the cable is laid, but in the future it will help at least roughly understand which way to look for the wires from the outlet or junction box.
What is a Walabot DIY Scanner?
To search for hidden communications with a smartphone, you will have to purchase a Walabot DIY device, which will complement the device.
This device includes:
- Walabot DIY scanner;
- Cable and adapter for connecting the scanner to a smartphone;
- Scotch tape for gluing the scanner to the back cover of the phone;
- Passport and instructions for working with the application.
The scanner is almost the same size as most modern smartphones. Its distinctive feature is its fairly large thickness. Externally, the device somewhat resembles a battery for charging mobile phones.
At the bottom of the scanner there is only one technological hole through which the scanner can be connected to a smartphone using the cable included in the kit. After connecting the scanner to the phone, the required application will be automatically installed, the devices will be configured, and the scanner will be ready for use.
Special devices and their operating principles
To identify hidden wiring, you can use special electrical devices - finders, of which there are quite enough on the electrical goods market.
It is noteworthy that such devices use different operating principles, which is why they have their own advantages and disadvantages.
So, you can purchase finders:
- Electrostatic. The operation of such devices is based on capturing the electromagnetic field that is formed in cables when electric current passes through them. Devices using this principle of operation are among the most common and inexpensive. They allow you to quite accurately find hidden wiring, provided that the walls being examined are dry and not damp, and there are no metal structures in them;
- Electromagnetic Wiring Finders. Their determination principle is the same as that of electrostatic ones, that is, they determine the presence of an electromagnetic field. But they have one feature - the wiring that needs to be found must be under load, and it must be at least 1 kW. Therefore, before searching, you must first plug something into the outlet, for example, an electric kettle, and then determine the location of the cable;
- Metal detectors. The peculiarity of such a device is that it itself creates an electromagnetic field. At the same time, metal that comes into the zone of action of this field will cause a change in it, to which the device will react. This device is convenient because it does not require powering the wires. But at the same time, it will react to all metal elements in the wall - nails, screws, wire, etc. Professional models, unlike amateur ones, can determine what kind of metal is hidden in the wall, which greatly facilitates the search.
Combined devices are also produced that use several operating principles simultaneously, which increases the accuracy of determination.
In addition, such devices often have additional functions that significantly expand their scope of application.
For example, a finder can additionally help in determining the location of a broken wiring or grounding, searching for a phase wire, etc.
Metal detector
The operation of the metal detector is based on the principle of induction balance between the transmitting and receiving coils. It operates in the range from 2 to 20 kHz, and records the phase shift when the coil is brought to the conductor. We carried out measurements using the cheapest and simplest metal detector, Pirat Pro, costing 2,500 rubles, which is mainly designed to detect ferrous metal. The illustration below shows the result of a wiring search.
As you can see, the metal detector clearly determines the location of the wiring. Its main advantage is that the wire is detected even if there is no voltage or load on it. Also, in panel houses you will see reinforcement in slabs, and in wooden houses - nails. But more expensive models allow you to cut out ferrous metals and find only copper or aluminum. However, the location area is increased by the size of the coil, so the error can be up to 5 cm. This method should only be used if you like to hunt for coins and you already have a metal detector.
Wiring Finders
Below are several types of devices that the market currently offers.
"Search".
The first device is called “Search” and it looks like this.
This device uses the electrostatic principle of detecting hidden wiring.
It has 4 sensitivity modes and is capable of detecting a cable at a depth of up to 7 cm. Light and sound indications are used for notification.
It has a number of additional functions and is very easy to use - select mode (the 4th mode is used to search for wiring) and move the device along the wall.
Please note that certain factors may affect its operation (presence of metal objects, high humidity of the wall).
In general, “Search” is a completely acceptable and inexpensive option for detecting wiring, but it does not apply to professional devices.
A large number of analogues of such a device are produced - the same “Woodpecker”, SPO and a number of others.
MAG-2.
The second device, MAG-2, looks like this.
Indicator screwdriver to help
This is the most effective of the “cheap” methods. The price is 100 - 150 rubles, but with its help you can determine the wire under the plaster with good accuracy. So, to identify the wire, you need to pinch the slot (tip) with your fingers, and move the back side over the location of the intended wire. When detected, the LED will light up red (or some other color). Please note that a screwdriver can detect a wire at a depth of no more than 2 cm, and it must be live. Therefore, if the wiring lies deeper, the screwdriver is unlikely to notice it.
In any case, every electrician should have an indicator screwdriver in his arsenal. Here, for example, is an inexpensive version of the ROBITON VT-005 indicator screwdriver, which allows you to determine voltage by contact and non-contact methods.
What else can help in finding hidden wiring?
The searchers that can be purchased for personal use were discussed above.
But it often happens that you need to find the wiring only once and for this it is not advisable to spend money on a special device, but you still need to find the wiring.
Indicator screwdrivers.
In this case, an indicator screwdriver can come to the rescue. It is better, of course, to buy a more modern one, for example, such is the Chinese MS series of indicator screwdrivers, which have a light and sound alarm.
But you can get by with a regular probe with an LED indicator.
They work on the electrostatic principle, that is, they are able to detect the electromagnetic field emitted by live wiring.
They are very simple to use - just put your finger on a special metal window (MS indicators) or touch the tip of a screwdriver (regular indicator), and then simply move the screwdriver along the wall.
In the place where the wire is laid, such indicators will begin to signal.
The disadvantages of this method of determination include a relatively small detection depth (up to 2 cm), as well as a strong error, that is, it will not be possible to accurately detect where the cable lies.
It will only be possible to determine a channel with a width of 10 to 20 cm. But this is often enough to carry out installation work associated with drilling a wall; you just need to do everything outside the boundaries of a certain channel.
Multimeter.
You can also use a multimeter for searching.
But the device itself is not enough; you will also need a field-effect transistor (an excellent option is KP103). Read how to test a transistor with a multimeter here.
To get a finder, you need to connect the specified elements correctly. Such a transistor has three terminals - drain, source, and gate.
We connect the probes of a multimeter, switched to ohmmeter mode, to the first two terminals, and the polarity is not important.
The shutter will play the role of an antenna (which can be slightly lengthened).
Having built such a device, you can start searching - we move the antenna along the wall and look at the multimeter readings - any deviations in the readings will indicate the location of the cable.
Smartphone.
A smartphone with Mac or Android OS can also help with identifying hidden wiring.
For them, you can find the “Metall Detector” program or its equivalent in the application store.
The magnetic sensor built into the smartphone in combination with the specified software allows you to get a metal detector that can detect a cable hidden in the wall.
But it is worth considering that it will react to all metal elements, so it cannot be used everywhere.
The search accuracy of a smartphone is sufficient to determine the channel in which the wiring is laid.
Professional search devices
There are many techniques that allow you to find out where cables are laid. They are based on the use of devices capable of detecting wires without direct contact. These include the following devices:
- electromagnetic hidden wiring detector;
- indicator screwdriver;
- metal detector;
- multimeter and field effect transistor;
- combined detector.
Electromagnetic hidden wiring detector
Electromagnetic detectors are professional devices manufactured for detecting wires. Their work is based on recording alternating electromagnetic fields coming from the conductor. This type of device requires that a current of 5-10 amperes flow through the probed cable during the search. This corresponds to an electrical load of 1-2 kW.
Wire detector
The electromagnetic device for finding wiring has good accuracy. But there is one big drawback. It is able to detect a wire if current is flowing through it. It will not be possible to find an open circuit with such a device. Accordingly, the house must be energized, and the line being tested must not have a wire break. This type of detector is perfect if the cable is in working order, and you need to make a hole in the wall without unnecessary risks.
Indicator screwdriver
The cheapest method for detecting hidden wiring. The indicator costs about 20-30 rubles. Every electrician has one. Electricians use it to find phase and neutral. If you touch the cable with an indicator screwdriver, it will light up. Expensive models are capable of emitting a beep. Regardless of the price, the device points to the phase wire, but is silent to zero.
Finding the cable using an indicator screwdriver
Transistor modifications of indicator screwdrivers can glow without direct contact with the cable. Sensitivity allows you to detect phase wires at a distance of up to 20 mm. Therefore, if the current-carrying conductor is located at a shallow depth, the device will detect it. It is important that the wire is live and the indicator is transistor.
Metal detector
This device is often called a metal detector. It is used to determine the presence of metal in the earth at a depth of about one meter. If there are no metal fittings in the walls, nothing prevents you from using a metal detector to search for wiring.
The use of a metal detector is superior to other search methods. The cable does not need to be live to detect a wire. The device is designed to search at great depths, so it can easily find a wire in a wall at distances of 1-5 cm. Cables are usually laid at this depth.
However, you cannot use a metal detector in a building with fittings. The device works on any metal, and not specifically on electrical wiring. Metal detectors are quite large in size. They are problematic to store in a standard tool box.
Multimeter and field effect transistor
Determining hidden wiring with a multimeter is suitable for radio amateurs. The sensitive element for searching will have to be soldered by hand. In addition to the measuring device, a field-effect transistor is useful. The main thing is that its gate has a low opening voltage and a low input capacitance. For example, Soviet elements of the KP103 series or imported 2SK241. It is also permissible to use an old pointer tester as a device.
The multimeter is switched to high resistance measurement mode. Typically these are ranges up to 200 kohms or 2 megohms. The probes of the device are connected to the drain-source junction. The shutter remains hanging in the air. To increase the sensitivity of the search, a piece of wire should be soldered to it. The length and shape of the segment are selected experimentally. Care must be taken when assembling the device. KP103 are not the cheapest transistors. They are easily damaged by static electricity.
Combined detector
Combined hidden wiring detectors are a class of devices that have several sensitive elements. For example, a metal detector and an electromagnetic detector in one compact housing. Two types of sensors, working simultaneously, eliminate each other's shortcomings and errors.
Combination appliances are more expensive than their simpler counterparts. A person who is looking for a network fault can, at his discretion, turn on or off one or another type of sensor or use several at the same time. It all depends on your experience with the detector and the condition of the wiring being examined.
Alternative methods
Visual search.
If these devices are not available, then alternative methods can be used. And the first of them is visual.
In the process of sealing grooves with cables, it is not always possible to do everything very smoothly.
Therefore, it is often possible to detect the location of the wiring along a small protrusion, but for this you need to carefully examine the room, and the wallpaper will have to be removed - the wall must be “bare”.
Radio.
An ordinary radio receiver, which does not need to be modified, can also help in the search. It is enough to set the frequency on it to 100 kHz. And then we take the receiver and go searching.
To detect, we move the antenna along the wall. The cable detection signal will be an increase in noise from the speaker.
The accuracy, of course, is not high, but it is quite possible to determine the channel with the wiring.
You can also use an old tape recorder or cassette player, but to do this you need to extend the wiring going to the magnetic head. This will be the antenna.
That is, we carefully remove the head from the player, extend the wires, and then move it along the wall.
Popular with readers: How to choose a cordless screwdriver, the pros and cons of the device.
Looking for hearing aid wiring
Old-style hearing aids will allow you to determine the location of the wiring with “average” accuracy. Some hearing aids, such as the AK-1 model, have a “phone” mode that allows hearing-impaired people to talk on the phone without extraneous noise. In this mode, the device will be sensitive to fluctuations in electromagnetic waves. Now you just need to follow the wall in the place where you think the wire should lie. As soon as you hear a characteristic crackling sound, you have stumbled upon a wire. Its error is approximately the same as that of a radio receiver.
Old-fashioned methods
Of course, previously, to detect wiring in the wall, they did without instruments, but they safely found the entire power line under wallpaper, tiles and plaster. How did our grandfathers and great-grandfathers do it?
We present to your attention the three simplest options that will allow you to find the wiring yourself:
- If a major renovation is planned. You tear off the wallpaper and inspect the wall in the Khrushchev building (or in the house). Typically, the grooves for hidden electrical wiring are slightly different in color from other areas of the surface, and the putty will be rougher to the touch.
- Take an ordinary radio receiver, tune it to 100 kHz and bring it to the required zone. In the place where the current passes, the receiver will begin to make more noise.
- An alternative to the radio is to use a microphone on the radio. Turn on the microphone and carefully move it along the surface. There is a noise or crackling sound - you have managed to find the approximate location of the route.
We draw your attention to the fact that methods that use a microphone and a receiver have a fairly high error of 15 cm. That is why, relying on the signals of these devices, it is better to play it safe and retreat a little more so as not to receive an electric shock! https://www.youtube.com/embed/EL_64-lzhaE
That's all the instructions for using devices to detect hidden electrical wiring in the wall. We hope that now you know exactly how to find the wire and power cable under the plaster in the house without anyone’s help!
Related materials:
Using a Multimeter
To find hidden wiring using a multimeter, it must be supplemented with a field-effect transistor, for example KP103. The multimeter probes should be connected to the “drain” and “source” terminals. The “gate” pin will act as an antenna, which can be extended with a small wire.
To find hidden wiring with this finder, you need to move the antenna along the wall, observing the readings of the device. Any deviations of its arrow will indicate the presence of hidden wiring in the thickness of the wall.
Are you planning to install electrical wiring in your home? Be sure to check out this article, where we talk about the basic rules for installing it.
Procedure for eliminating a broken hidden cable
After finding the exact location of the break using one of the above methods, the wire should be connected. To do this, you must first turn off the phase, and then use a hammer to open the cable groove approximately 10 cm to the left and right of the damage site. Then the broken core must be carefully separated from the conductor without disturbing the insulating layer on other cables.
The further procedure is as follows:
- Move the ends of the broken cable apart.
- Using a hammer drill and a special bit, drill a hole in the wall. It must be large enough to accommodate the branch box.
- Insert the box into the hole and secure it there with alabaster, and then place the cables in it.
- Connect and insulate damaged wires.
- Once the damage has been repaired, close the box with the lid.
- Plaster the previously opened section of the groove.
If the damaged cable is located inside a special tube, then it must be carefully pulled out, and a new conductor must be tightened in its place using a pulling device.
The video shows the process of restoring the wire:
The above process is carried out when repairing a broken phase. Restoring the neutral wire is carried out in almost the same order, with the exception of the initial stage. When repairing a zero, first of all, the damaged cable must be separated from the bus. Then the zero is attached to the phase. Further work is carried out in a similar sequence.
Detector based on 555 circuit
A 555 integrated circuit can be used to make the detector.
It is used to generate single, constantly repeating pulses and is often used in the manufacture of timers, electronic and digital relays, and other electronic devices.
You will need:
- one NE 555 chip;
- fixed resistors 1, 2, 10 kOhm;
- variable resistor 10 kOhm;
- capacitor 47 uF 166 V;
- battery "Krona";
- plastic case;
- universal printed circuit board.
Assembly is carried out in accordance with the diagram presented above. If all elements of the circuit are working properly, then when the device approaches the wires in the wall, the built-in 555 integrated circuit begins to produce short signals that are displayed on the LED.
If necessary, a signaling device can be built into the finished device, which will make a sound when hidden wiring is detected. In order not to constantly remove the battery from the cell, a switch can be added to the design.
Homemade structures for determining the location of electrical wiring in the wall
On the Internet it is proposed to assemble the simplest devices for searching for electrical wiring in the wall. The first of them operates on the basis of the K561 LA7 microcircuit. We believe that any similar type will be suitable for the search. Through a resistor with a nominal value of about 1 MΩ from the electrical wires, the signal arrives at both inputs of the logical NAND function. When signs of reception appear, the internal amplifiers form a viable “zero”. We feed it to another AND-NOT chip, and connect the unit to a piezo bell. The Chip&Dip store recommends using ZP-3 for this purpose.
Wiring detector
We believe that this is far from the only option, but we would like to add that in digital technology there are several families of microcircuits. You need to take a device with a lower response threshold. But the sensitivity of the device will increase greatly. For example, there are sets of logic:
- K651 LA7 belongs to the CMOS family (complementary metal oxide semiconductor transistors). From the specification we understand that the high-level input voltage must be at least 7.2 V. With a field strength of 500 V/m, this will require a piece of wire no shorter than 1.5 centimeters. The calculation is approximate, but there may be interference around. A level of 0.5 kV/m is considered the maximum permissible, as we mentioned earlier.
- The TTL series (transistor logic) has a logic level of one of the order of 2 - 2.5 V, depending on the specific series. What makes this type of device more suitable for building a sensitive detector. For example, the KR1531 LA4 microcircuit contains three fully functional NAND elements. The response threshold is about 2.7 V, which is three times lower than in the previous version.
- The ECL series (emitter-coupled logic) has inverted levels and was considered promising. Minus 1.7 V is needed for logical zero. But now remember that the voltage is variable, since the field is electromagnetic. We don't see any difficulties here. You need to find, by analogy, a microcircuit of NAND elements, power it correctly, turn on the antenna wire from the first end, and from the second - a bell on any element that recognizes negative voltage. For example, ZP-3 but with a different polarity.
Search for electrical wires
I would like to add about the operating principle of such a detector:
The small signal is picked up by the bare wire. The length should be further away from quarter-wave WiFi antennas (2.4 or 5 Hz) to reduce interference. Through a resistance that limits false operation from interference, voltage comes to the NAND element. Inside there are amplifying nonlinear elements, similar to transistors, that bring a small signal to a stable zero and one in the local digital logic system. Then, through another element, the signal is sent to the indicator. For example, an LED is from the same logic as the microcircuit. For example, the Chip&Dip store suggests using a sliding ammeter scale for this purpose. Anything that can be obtained and controlled after being included in the device will do.
Whether the method turns out to be visual or auditory is not so important.
Electrical wiring in the wall does not radiate as long as there is no consumption. In a free state, the energy meter does not work: a load is needed. If the electrical wiring is on the ceiling, turn on the chandelier, if on the wall, turn on the electric kettle. In this case, energy begins to flow through the vein, part of it is emitted into free space.
