Types of hidden wiring detectors and do-it-yourself wiring diagrams

During repairs in the apartment, you have to look for places where the electrical wires laid inside the walls are located in order to exclude electric shock when drilling. Only a hidden wiring detector can find the cable in this situation. You just need to choose the right model of the device or make a similar finder with your own hands. The stores offer various devices in terms of functionality and principle of operation, the choice is quite extensive. But with minimal knowledge in electrical engineering, the tool can be assembled independently.

Preliminary search for hidden electrical wires is the key to the safety of drilling walls

Types and principle of operation of electrical wiring search devices

Live wiring is a risk to life. When searching for it, it is best to exclude the use of the “scientific poke method” using a drill drill. The risk of electric shock in this case increases dramatically. You should not save too much here, wire detection devices cost a little.

Professional appliances

When searching for electrical wiring hidden in the walls, four types of detectors are used:

1. Electrostatic.
2. Electromagnetic.
3. metal detectors.
4. Universal (combined).

Electromagnetic detector

All these devices are compact and easy to use. The first option finds the wires immured in the wall by detecting their electrostatic, and the second - the electromagnetic field. Metal detectors look for copper and aluminum that make up the cores of an electrical cable. Universal models use two or more search principles.

metal finder

Advice! The cheapest are electrostatic and electromagnetic detectors. But they can only detect live wires.

Search for the source of danger

The devices of the first two types of detectors have a couple of significant drawbacks:

• First, they are not able to detect dead wiring.
• And secondly, if the walls are wet or made of metal structures, then there will be zero sense from detectors of this class.

The metal detector finds metal electrical wires, fittings and pipes

The search with an electrostatic detector is more accurate, however, only on condition that a load of 1–1.5 kW is included in the outlet. It is problematic for them to find the electric wires going to the light bulb, and it will not be possible to detect low-current lines at all.

Hidden wiring is easily detected by a metal detector, even if it is not energized. But the device also reacts to any metal in the walls. He does not see the differences between fittings, residential wire and a metal pipe. The meter will give the same sound or color signal about detection in all cases.

Video: Review and testing of detectors

What is the best tool for finding electrical wiring

A classic example of an electromagnetic wire detector is a remote indicator screwdriver for detecting a phase in an outlet. You just need to use a modern device with a battery inside, due to which the device is able to capture the weakest fields. In terms of functionality, it can be ordinary glass or with a display. The main thing is that it has a non-contact operation mode.

However, in practice, the method with a screwdriver can only be used if wires are found that are not deep in the wall. Under a thin layer of plaster, this indicator will find the wiring. However, a search in the thickness of concrete or brickwork will not lead to a positive result. Here you need a different electrical appliance.

Advice! If you need maximum accuracy with determining the location of the wire up to a centimeter in any wall, then you cannot do without a universal hidden wiring detector.

Indicator screwdriver device

Electrostatic and electromagnetic field detectors can only find electrical wiring when operating in dry conditions. If the walls are damp inside or outside, then such devices will not detect anything. On the street in rainy weather, there will be no sense from them either.

Combined instruments are capable of determining:

• type of metal in the veins;
• depth of hidden wiring;
• wall material (plastic, wood, ferrous or non-ferrous metal).

Tester device

However, universal models often have advanced functionality, which is practically not used by the master at home. There are functions, but they are not used. And you have to pay money for them, the manufacturer has laid everything in the cost of the device.

Electrical wires in the wall can be laid at any angle

It is best to select a wiring detector that is optimal in terms of price and functionality, focusing solely on your own needs. Much depends on the material of the walls in which the search is made. But for one-time work, in most cases, an indicator screwdriver or a simple, cheap electrostatic device is enough. However, if you have to work with electrical wires all the time, then it is better to purchase a multifunctional device.

Russian detector "Dyatel"

How to choose a detector in a store

When choosing a device for detecting hidden wiring, you need to look at it:

• scanning depth;
• type of signal indication;
• the ability to distinguish between different materials and identify voids in the walls;
• possibility of detecting the place of wire break.

The more informative the display, the more accurately the location of the wiring is determined.

The main thing is the depth of detection of electrical wiring. For cheap models, it is 10-20 mm, which is not always enough. For home needs, it is best to take a device with an average scanning depth of 50–60 mm. Deeper than five centimeters, the electrical wire in the walls of private houses and apartments is extremely rarely laid.

The second parameter is a signal about the detection of a wire in the thickness of the wall. It can be sound or color. To eliminate errors, it is better to take the device with two types of information feed. And the sound should be tonal, which emits different melodies depending on the distance between the device and electrical wiring or metal.

How the finder works

The most convenient to use is a detector with a liquid crystal display. On such a screen, information is displayed in an accessible form in the form of icons and rulers with stripes. But in many cases, simple LEDs on the case are quite enough. It all depends on the preferences of the master and the amount of money planned for the purchase.

Before purchasing the selected device directly in the store, it should be tested. There are working electrical appliances nearby in any scenario. To assess the veracity of the depth stated in the data sheet, the wire going to them can be covered with some kind of plastic panel or wooden board.

wall study

Homemade products to search for hidden wiring

If you have experience with a soldering iron and knowledge of the basics of electrical engineering, you can make a wiring detector with your own hands. To do this, you need a minimum set of radio components, which will cost several times less than a ready-made store device.

Video: How to make a do-it-yourself wiring detection device

Device with multi-stage voltage multiplication

With your own hands, the detector for searching for wiring in the wall is easiest to assemble in the form of three cascades that amplify the voltage from the antenna input. When fixing the electromagnetic field, the signal from the antenna enters the first of them, creating a small current in the circuit. Then this current is amplified by the following stages to a value sufficient to light up the LED. If the latter lights up, then the live electrical wire is located directly under the signaling probe.

To assemble the appliance you will need:

• Three sensitive transistors (bipolar triodes BC547).
• Three resistors (220 Ohm, 1 kOhm and 1 MΩ).
• LED as an indicator.
• 6 V power supply.

Three-transistor detector circuit

Together, the elements can be quickly connected by free soldering. The printed circuit board is not needed here. It is only necessary to insulate the soldered contacts and put everything in a plastic case so that when held by a hand, it does not work falsely from human electrostatics. Only a small plate used as an antenna should be metal. It connects to the base of the first transistor.

Important! The larger the antenna area, the more sensitive the device is. With high sensitivity, the risk of false positives increases, but the scanning depth is greater.

General view of a homemade detector

The size of the metal plate should be such that the detector works exclusively on the wiring, and when it comes into contact with the hand, the indicator LED does not light up. The plate will need to be cut to the desired size, checking the device on a live wire.

Radio receiver with response to electromagnetic fields

The second version of a home-made device for determining hidden wiring is more difficult to perform, but its search accuracy is higher. It allows you to detect not only live electrical wires, but also metal in the wall. After spending a little time and using the attached diagram, you can assemble a portable and fully working metal detector with your own hands.

To assemble this search device you will need:

• Chips KR-140UD-1208 (D1, D2) and K-561LE5 (D3).
• Resistors 510 ohm (R10, R17), 1k ohm (R1, R19), 2k ohm (R11), 4.7k ohm (R2), 15k ohm (R3), 36k ohm (R9), 47k ohm (R5), 100k ohm (R4, R18), 130 kΩ (R7), 160 kΩ (R14), 200 kΩ (R8, R12), 680 kΩ (R15), 910 kΩ (R13) and 1 MΩ (R6).
• Transistor KT315 (T1).
• Capacitors 0.022 uF (C3), 0.033 uF (C5), 0.1 uF (C1, C4), 1.0 uF (C2), 1.5 uF (C6).
• Diode KD522 (VD1).
• LEDs No. 1 for a signal for the presence of metal and No. 2 for wiring.
• SW1 switch.
• Speaker SP.
• 6-9V power supply.

Diagram of a small combined detector

Antenna A2 is made in the form of a probe made of copper wire 5-10 cm long. A1 consists of a pair of coils on a five-centimeter ferrite rod with a cross section of 10 mm. Both windings are made of wire D = 0.15 mm. The first has 60 turns, and the second has 5.

Antenna A1 is used to find metal in the wall. When detected, the LED lights up and clicks are heard from the speaker. A2 is used to search for the electromagnetic field of the powered wiring. In this case, the LED starts flashing in time with the frequency of the current in the wire.

The simplest field-effect transistor wiring detector

Finder from a multimeter and a field effect transistor

If you don’t want to solder, and you need to find hidden wiring in the apartment urgently, at least approximately, then you can use a field-effect transistor. But to detect a signal, you will have to connect a multimeter to it in ohmmeter mode.

When exposed to an electric field generated by an electrical wire under voltage, the thickness of the p-n junction of the transistor increases. This change is recorded with an ohmmeter. When assembling such a device, the main thing is not to confuse the connection of the leads. The outputs of the “source-drain” are connected to the multimeter, and the “gate” remains free. The latter, together with the metal case of the transistor, will play the role of an antenna.

To perform a search with the resulting device, it is necessary to draw along the wall. When approaching the wiring, the multimeter needle will fluctuate, indicating an increase in resistance. The receiving antenna in this circuit can also be replaced by the primary winding of the transformer. The choice here depends on the availability of a specific element base at hand.

Video: Making a do-it-yourself finder according to the scheme

Smartphone as a wire detector

Fans of modern gadgets can also use an Android smartphone to search for wires embedded in the wall. To do this, you need to download the appropriate Metal Detector application. In this case, the built-in navigation compass will serve as an antenna, which easily captures the magnetic field of a metal wire at a shallow depth in the wall.

Smartphone testing

A simple indicator of hidden electrical wiring can always be assembled with your own hands. But the quality of detecting homemade power lines will be low. If the wires are buried deep, they can only be found with the help of a professional device with several operating modes. The model range of such devices is now huge, but before choosing, you need to accurately determine the required search parameters. Extra features cost money, but are not always in demand.