Voltage indicator. brief description, rules of use

Even for the simplest work in electrical circuits on the farm, a voltage indicator is useful - a device that shows the presence or absence of electric current and voltage in networks from 220 to 1000 V (depending on the device). The expediency of its use is dictated primarily by the fact that the electric current cannot be seen with the eyes - its presence can only be judged by whether the device plugged into the outlet is working or not.

Terms of use

When starting to work with a voltage indicator, you need to make sure that it is intact and operational.
The potential difference for which it is intended must be higher than the operating voltage of the electrical equipment being tested. The indicator's next laboratory test date must not be past due. Before working with a low voltage indicator (LVI), it must be checked for functionality. To check, you can use a connected socket with a voltage of 220 V. A single-pole indicator should determine the phase, and a two-pole indicator should determine the presence of 220 V.

To check the high voltage indicator (HVI), its probe is brought closer to parts of the electrical installation to which high voltage is applied. The alarm should sound. All operations with UNN must be done with dielectric gloves.

Some work in the house can be performed by people without special training, without resorting to the services of professional electricians. Replacing sockets, switches, and repairing table and ceiling lamps do not require high qualifications.

But when performing this work, you must follow safety rules, which require checking that there is no voltage at the contacts of electrical appliances before starting work.

Single-pole voltage indicator

- the simplest and most accessible device for everyone, indicating the presence or absence of a “phase”. Some models are also used to search for breaks in wires, cords and cables. Since some single-pole indicators combine the function of a simple screwdriver, they are called “indicator screwdrivers”, and sometimes simply “indicators”.

The advantage of indicators is that they do not require a second wire to operate. They use current passing from "phase" to "ground" through the pointer and the human body, connected in series. This current does not pose a danger to humans. It is not hampered by the resistance of shoes or the floor material, but you cannot use the pointer while wearing dielectric gloves; it will not work. In practice, there were isolated cases when the indicator screwdriver did not detect the presence of a “phase” in the lamp if the electrician was standing on a dry wooden stepladder.

Types of indicators

The simplest indicator is a simple screwdriver, inside of which it is located. Such a device can help you distinguish zero from phase. A two-pole indicator will be more advanced, although you can also take a single-line option.

The latter operates within 200 volts, but goes completely blind when the voltage level drops below 70 volts. It is capable of interacting only with open sections of wiring, sockets and other working areas of the circuit that are not hidden in any way.

Such a device cannot be used when working with networks under voltage of 380 volts. Also, it is not suitable for finding hidden contours. Make sure that there is no battery inside the indicator, otherwise it is better not to buy the device, since such models often show inaccurate readings.

Indicators for two working bands work on the same principle as the first option, only they have a higher range - they can work with networks up to four hundred volts. True, the wiring is of a hidden type and will not be revealed to him.

Single-band and double-band voltage indicators are most necessary for checking the phase in a particular wiring. They look at the order of wires in sockets, switches, and conductors.

Never, hear, never test wires for voltage with your hands or a spark contact. Also, do not connect a device with exposed wiring to a network of 220 volts or higher. Such manipulations can lead to injury, fire, short circuit, and even death. Electricity is no joke.

AC and DC voltage indicator up to 600 V

The next option is a slightly more complex system, due to the presence in the circuit, in addition to the elements already known to us, of two transistors and a capacitance. But the versatility of this indicator will pleasantly surprise you. It can safely check the presence of voltage from 5 to 600 V, both direct and alternating.

The main element of the voltage indicator circuit is a field-effect transistor (VT2). The threshold voltage value that will allow the indicator to operate is fixed by the gate-source potential difference, and the maximum possible voltage determines the drop at the drain-source. It functions as a current stabilizer. Feedback is provided through a bipolar transistor (VT1) to maintain the set value.

The operating principle of the LED indicator is as follows. When a potential difference is applied to the input, a current will arise in the circuit, the value of which is determined by the resistance (R2) and the voltage of the base-emitter junction of the bipolar transistor (VT1). In order for a weak LED to light up, a stabilization current of 100 μA is sufficient. To do this, the resistance (R2) should be 500-600 Ohms, if the base-emitter voltage is approximately 0.5 V. A capacitor (C) is required to be non-polar, with a capacity of 0.1 μF, it serves as protection for the LED from current surges. We select a resistor (R1) with a value of 1 MOhm; it acts as a load for the bipolar transistor (VT1). The functions of the diode (VD) in the case of DC voltage indication are pole testing and protection. And to check the alternating voltage, it plays the role of a rectifier, cutting off the negative half-wave. Its reverse voltage must be at least 600 V. As for the LED (HL), choose so that its glow at minimum currents is noticeable.

Indicator for microcircuits - logic probe

Having learned how to create a simple electrician's probe with your own hands, you can also make a simple logic probe based on LED, which will help you find faults in digital devices.

Logic probes have been around since the early days of computing. With their help, specialists analyzed the logical levels at the inputs and outputs of digital microcircuits. The high level (voltage) at the output of the logic element is assigned the value of logical “one”, and the low level is assigned the value of logical “zero”. By comparing the levels at the input and output of a digital microcircuit, you can judge its serviceability.

Types of devices

Indicators up to 1000 volts and above 1000 volts have different external and design features. For low-voltage measurements, up to 1 kV, there are two types of devices:

single-pole, responsive to the flow of capacitive current;
bipolar, gives an indication when active current flows through it.

The single-pole indicator is designed to work in alternating current circuits, to detect phase conductors, in lighting circuits, when phasing an electric meter, and checking cartridges in lamps. Simply put, to detect live wires.

Single-pole phase indicating devices have the same design and typically consist of a gas-discharge indicator lamp, with an ignition threshold of 90 to 120 volts, and a 1 MΩ resistor connected in series. The resistor limits the current to a safe value, about 0.5 mA.

The IN - 90 indicator is made in the form of a screwdriver.

The disadvantages of such indicators include low sensitivity (the indication threshold of some devices starts at 90 volts), as well as sensitivity to interference in neighboring wires.

For networks above 1000 volts, voltage indicators are made with handles made of insulating material and long, preventing a person from approaching current-carrying elements. The appearance of the UVN-10 is shown in the photo below:

When measuring voltages above 1000 volts, they resort to the use of additional protective equipment: rubber gloves, boots or an insulating mat. You can find out from our article!

A two-pole indicator consists of two housings made of insulating material and a flexible insulated copper conductor that connects them. Diagram of a two-pole voltage indicator type UNN-10:

In this circuit, the gas-discharge indicator is shunted by a resistor, which makes the circuit insensitive to induced voltages. Also based on it, an indicator with a voltage indicator UN-1 is produced:

This device uses a special linear gas-discharge lamp and a scale on the body with graduations of 127, 220, 380, 500 Volts.

There are also universal voltage indicators for checking the presence of voltage and indicating its value from 12 to 380 V. For operation in DC circuits, up to 500 volts, and alternating current, up to 380 volts. They can additionally be used to test the integrity of connections.

These devices use LEDs as light indicators, and a large capacitor as a power source.

The digital voltage indicator has an LCD screen with printed values in volts. At a maximum value of 220 volts, all values from minimum to maximum are displayed on the screen. Those. This tester shows an approximate value. The only advantage of this model is the lack of a power source.

Non-contact indicators are designed to detect live conductors, including those hidden in walls or panels. The circuitry of this device responds to an alternating electromagnetic field and is equipped with light and sound indication. We talked more about these devices when we talked about .

DIY LED voltage indicator

Checking the voltage in the circuit is a procedure necessary when performing various types of work related to electricity. Some amateur electricians, and sometimes professionals, use a homemade “control” for this - a socket with a light bulb to which wires are connected.

Although this method is prohibited by the “Rules for the Safe Operation of Consumer Electrical Installations,” it is quite effective when used correctly. But still, for these purposes it is better to use LED identifiers - probes. You can buy them in a store, or you can make them yourself.

What is a logic probe used for?

This device is successfully used when it is necessary to perform a preliminary check of the operability of the elements of a simple electrical circuit, as well as for the initial diagnosis of simple devices - that is, in cases where high measurement accuracy is not required. Using a logic probe you can:

Determine the presence of a voltage of 12 - 400 V in the electrical circuit.
Determine the poles in a DC circuit.

Check the condition of transistors, diodes and other electrical elements.
Determine the phase conductor in the AC electrical circuit.
Ring the electrical circuit to check its integrity.

The simplest and most reliable devices with which the above manipulations are performed are an indicator screwdriver and a sonic screwdriver.

Electrician's probe: principle of operation and manufacture

A simple identifier with two LEDs and a neon light bulb, which has received the name “arcashka” among electricians, despite its simple device, allows you to effectively determine the presence of a phase, resistance in an electrical circuit, and also detect a short circuit (short circuit) in the circuit. The universal electrician's tester is mainly used for:

Diagnostics for broken coils and relays.
Continuity checks of motors and chokes.
Checking rectifier diodes.
Definitions of terminals on transformers with multiple windings.

This is not a complete list of tasks that can be solved using a probe. But the above is enough to understand how useful this device is in the work of an electrician.

A regular battery with a voltage of 9 V is used as a power source for this device. When the tester probes are closed, the current consumption does not exceed 110 mA. If the probes are open, then the device does not consume electricity, so it does not need either a diagnostic mode switch or a power switch.

The probe is capable of performing its full functions until the voltage at the power supply drops below 4 V. After this, it can be used as a voltage indicator in circuits.

During the continuity of electrical circuits, the resistance of which is 0 - 150 Ohms, two light-emitting diodes light up - yellow and red. If the resistance value is 151 Ohm - 50 kOhm, then only the yellow diode lights up. When a network voltage of 220 V to 380 V is applied to the probes of the device, the neon lamp begins to glow, and at the same time a slight flickering of the LED elements is observed.

The diagram of this voltage indicator is available on the Internet, as well as in specialized literature. When making such a probe with your own hands, its elements are installed inside the housing, which is made of insulating material.

Often, for these purposes, the housing from the charger of any mobile phone or tablet computer is used. A probe pin should be removed from the front part of the case, and a high-quality insulated cable, the end of which is equipped with a probe or an alligator clip, should be removed from the end part.

Assembling a simple voltage tester with an LED indicator is shown in the following video:

How to make an electrician's tester with your own hands?

Some thrifty hobbyists can find many useful things in their “arsenal,” including an earphone (capsule) for the TK-67-NT telephone.

Another similar device, equipped with a metal membrane, inside which there is a pair of series-connected coils, is also suitable.

Based on such a part, a simple sound probe can be assembled.

First of all, you need to disassemble the telephone capsule and disconnect the coils from each other. This is necessary in order to free their conclusions. The elements are placed in the earphone under the sound membrane, near the coils. After assembling the electrical circuit, we will receive a completely working identifier with sound indication, which can be used, for example, to check the tracks of printed circuits for mutual bridging.

The base of such a probe is an electric generator with an inductive opposite relationship, the main parts of which are a telephone and a low-power transistor (preferably germanium). If you do not have such a transistor, then you can use another one with NPN conductivity, but in this case the polarity of the power supply should be changed. If you cannot turn on the generator, the terminals of one (any) coil must be swapped with each other.

You can increase the sound volume by choosing the frequency of the electric generator so that it is as close as possible to the resonant frequency of the earphone. To do this, the membrane and the core must be placed at an appropriate distance, changing the interval between them until the desired result is obtained.

Double pole design

A high voltage indicator with two measuring contacts works on the principle of detecting the passage of current through a section of the circuit. An internal circuit compares the potential difference between the measuring point and ground (or neutral contact). If the response threshold exceeds the set value, an indication is triggered.

The design may be different, depending on the purpose: indication only, search for breakdown, measurement of the exact voltage value, setting the range (220 V, 380 V). As an example, the illustration shows an electrical circuit of a device that determines the presence of a phase in the measured area and an approximate voltage threshold.

There are no complex integral elements, so this indicator is reliable and trouble-free under any operating conditions. If measurements are taken outdoors, in bright light - parallel to the light indicator (in this case, an LED element), a sound is added.

By adding a voltage measurement module to the measuring circuit, we get a single-mode multimeter designed for safe high voltage measurements.

Using such a device is not difficult: the passive contact on the connecting wire is applied to the ground (zero) bus of the electrical installation. Then the measuring contact must touch the potential measurement point.

Advantages:

high measurement accuracy, functionality can be expanded if necessary;
ability to work with high voltage without additional operator protection equipment;
operator protection is ensured: there is no direct contact with open areas of the body.

Flaws:

higher cost;
The meter is quite bulky.

Indicators with voltage more than 1 kV

This device is equipped with a neon lamp. The connection diagram is serial, with a capacitor base. It is suitable for detecting alternating current, and there is no need to touch the contacts with your fingers.

The voltage here is higher than in other devices, so do not neglect safety rules. Be sure to have gloves in your arsenal (rubber ones are best). It is also necessary to check the instrument every time to avoid breakdowns and inaccurate measurement results.

How to carry out test monitoring of the device's serviceability? Just check the pointer on a section of the network that definitely has electric current. There are special devices that create voltage for the indicator, and then the owner will be able to verify the correctness of the values demonstrated by the voltage indicator.
Sometimes work with stress takes place, for example, in a garage. There is a method here that will help you make a test measurement. Start your car or motorcycle and bring your device to the engine. Voltage occurs in the spark plugs, and the gauge will accurately show the result.

Never ground the voltage indicator! This may result in an electric shock and damage the device itself. Grounding is an unnecessary procedure for the device, because it does not affect the accuracy of operation.

Single-pole voltage indicators

Just like they require touching only one live part. “Earth” in this case will be provided through the body of a person, who, by touching a special contact of the voltage indicator, closes the current flow circuit. As a result, an electric current flows through a person, which does not exceed 30 mA and is safe for his life and health.

Such voltage indicators are usually made in the form of automatic pens. Their body has an inspection hole and is made of insulating materials.

The housing, as you probably already guessed, contains a resistor and a signal lamp. A metal flat contact is attached to the upper end of the housing for touching with the operator’s finger, and a metal probe is placed at the lower end of the housing, which touches live parts.

Such voltage indicators require touching not one, but two parts of the electrical installation. The principle of operation is the glow of a neon lamp or incandescent lamp (power no more than 10 W) when current flows through it, which arises due to the presence of a potential difference between the parts of the electrical installation to which the indicator is currently connected. In this case, the lamp consumes very little current (several milliamps), but at the same time provides a fairly stable and clear signal.

To limit the current flowing through the lamp, a resistor is placed in the circuit in series with the lamp.

Two-pole voltage indicators are suitable for AC and DC installations. However, when using this device in an alternating current circuit, the metal parts of the indicator (probe, lamp base, wire) can create a capacitance relative to the phase or ground sufficient for the lamp to light up when touching just one phase of the electrical installation. Therefore, this circuit is supplemented with a shunt resistor, which bypasses the neon lamp.

Instead of a voltage indicator, it is prohibited to use a regular incandescent lamp screwed into a socket (it is called a test lamp) charged with two wires. This is due to the fact that when the lamp is turned on at a voltage greater than it is designed for, its protective bulb may rupture, which can lead to injury to the operator or operators checking the presence of mains voltage.

Checking the presence of voltage with a single-pole voltage indicator:

Checking the presence of voltage with a two-pole voltage indicator:

Indicator screwdriver with advanced functions

This device is also equipped with a light indication and can be used in contact and non-contact versions. Both methods allow you to determine the presence or absence of normal or low voltage in the area being tested. In addition, the device makes it possible to check the condition of the circuit and its individual elements - fuses, cables and wires.

The index is divided into two main components. One of them is made in the form of a flat screwdriver that is in direct contact with the elements being tested. The second part is used to perform a non-contact voltage test. Both parts, complementing each other, make it possible to determine the integrity of the electrical circuit.

The LED electronic indicator is located in the handle made of transparent dielectric material. If there is a phase, a light signal is given. The batteries are also located here and serve as a power source.

Determination of phase and zero is carried out according to the same scheme as with a conventional indicator screwdriver. That is, the tip of the tool alternately touches the contacts. The presence of a phase wire is confirmed by a lit indicator. Non-contact testing is performed using the upper working part. In this case, the tool must be correctly held in the hand by the middle of the handle and not touch the lower working part. Failure to comply with this rule will lead to a transition to the dialing mode and the signal about the presence of a phase wire will be false.

The upper part of the indicator screwdriver is brought to the insulating coating of the conductor without touching its surface. The presence of a phase will begin to be detected as the pointer approaches the area being tested, and the indicator will give a light signal. The integrity of the conductors is determined by testing. This operation is performed in the complete absence of voltage in the network.

The check itself is performed in the following order:

Protective gloves must be removed and the upper working part of the device should be pressed with the finger of one hand.
Use the tip of the indicator to touch the wire core at one end. With your other hand you need to touch the second end of the conductor.
The activation of the indicator light indicates the integrity of the core being tested. If the probe does not work, then the core has damage, most likely a complete break. This method can be used not only for wires, but also for fuses.

How to determine the phase

The question is very simple, however, many simply do not know the answer to it. If you have any voltage indicator, even the simplest one, after reading the instructions for it you can easily figure out what’s what. In the case of a simple indicator screwdriver, you just need to insert it into the socket and touch the contact - if the light comes on, you have found the phase, if not, you have determined zero.

For a screwdriver to work correctly, it must contain a resistor with a resistance of one megaohm. If the screwdriver is from the Middle Kingdom, this part of it will be made in the shape of a grayish cylinder.

Despite its simplicity, a screwdriver with a voltage indicator helps out in the simplest and most banal situations, and is especially indispensable in everyday life.

If you are working with a liquid crystal modification, you need to know that when checking the system voltage with a load below 50 volts, you need to touch a special touch panel.

AC voltage indicator 220 V

Let's consider the first, simplest version of a network indicator on an LED. It is used in screwdrivers to find the 220 V phase. To implement it we will need:

Light-emitting diode;
resistor;
diode.

You can choose absolutely any LED (HL). The characteristics of the diode (VD) should be approximately as follows: forward voltage, with a forward current of 10-100 mA - 1-1.1 V. Reverse voltage 30-75 V. Resistor (R) must have a resistance of at least 100 kOhm, but not more than 150 kOhm, otherwise the brightness of the indicator will decrease. Such a device can be made independently in a hinged form, even without the use of a printed circuit board.

How it works

Understanding the operating principle of the device greatly simplifies its use and helps to avoid many mistakes, so it is important to familiarize yourself with the technology for determining voltage in advance:

Current flows into the device through the metal tip.
The resistor “detects” the voltage.
The current is transferred to the contact of the light bulb and the indicator light lights up.

The variability of the sequence of actions is varied and depends on the size and internal structure of the individual device and its additional equipment.

Instructions for operating the indicator UVNU-10SZ IP

The high voltage indicator UVNU - 10SZ IP and the phasing tube consist of 2 main parts: a working part and an insulating part with a handle. The links are connected to each other by screwing. Safety when working with the pointer and phasing tube is ensured by a ring-shaped stop on the body.

Before use you should:

Carry out an external inspection of the pointer and phasing tube, during which you should pay attention to the absence of cracks, peeling and other defects.

If there is moisture or dirt, remove it with a cloth. If the indicator fogs up in a warm room after storage or operation in the cold, it is necessary to keep it in this room for 15 minutes and wipe it dry with a napkin.

Before using the pointer, you must ensure that it is in good working order.

To do this, touch the probe (hook) with one hand (without gloves) and press the button on the end of the working part of the pointer with the other. Intermittent lighting and sound of the indicator indicate its serviceability.

If the skin resistance is high and the self-test does not work, you need to moisturize your fingers.

At low temperatures (below -25°C), if the self-test does not work, it is recommended to check the indicator as a voltage indicator on an installation that is known to be energized or using a special device for testing voltage indicators (UPUN).

When using the pointer as a voltage indicator from 100 to 1000 V, it is necessary to touch the metal parts of the tail of the working part with your hand and bring the probe (hook) to the current-carrying wire. The appearance of intermittent light and sound signals indicates that the current-carrying part is energized.

Phase-by-phase determination of the presence of voltage is carried out by contact method.

The operator needs to climb onto the support, or determine the presence of voltage by touching the current-carrying part from the ground, if there is an operational insulating rod ШО - 10 - 4 - 6.6, 6.6 m long; in this case, the working part of the pointer is fixed to the thread of the operating head of the rod.

When the probe (hook) touches the pointer to a live part that is energized, bright red flashes simultaneously appear with a frequent intermittent powerful sound signal.

To determine the presence of induced voltage on a de-energized and grounded electrical circuit. installation, you must first check the presence of voltage with a pointer.

After making sure that there is no voltage, it is necessary to re-check the presence of an induced voltage below the threshold (1.5 kV). To do this, it is necessary to separate the working part of the indicator from the insulating part, touching the metal parts of the tail of the working part with your hand (without gloves), and bring the probe (hook) to the current-carrying wire.

The presence of an indication and a sound signal indicates that the current-carrying part is under induced voltage.

When using an indicator with a phasing tube, it is necessary to connect the indicator to the phasing tube with the wire included in the delivery set, and insert the pin of the shunt wire into the hole made on the side of the working part of the indicator.

To avoid damage, the pointer should not be subjected to impacts or shocks.

Pointer tests

Laboratory tests are carried out by organizations that have a special license for this. To carry out the test, a circuit is assembled, which includes a high or low voltage indicator.

The UNN is tested for the insulation condition and the indication voltage value. They also check its operation at increased voltage, while measuring the current. The voltage, gradually increased from zero, is brought to exceed the operating voltage by 10% and is maintained for 1 minute.

Electrical installation diagram for testing the insulation of the housing and wires of the ULV up to 1000 V

The UVN is tested starting from the working part, applying voltage to the tip and screw connection. If the indicator voltage is higher than 35 kV, the working part is not checked, only the condition of the insulating part and the handle is tested.

Scheme of the testing facility for UVN

The results obtained are documented in a protocol and entered into a journal. A product approved for use is equipped with a tag with a stamp indicating the date of the next verification.

Voltage gauges and indicators are used to ensure the safety of operating personnel during work; they can also be fraught with danger. Storage, correct use and daily visual inspection must be ensured by those directly using the indicator. It is prohibited to use the device if the inspection period has expired, or if it has been subjected to mechanical damage as a result of a fall or impact.

Types of indicator screwdrivers and their features

Voltage indicators are presented in a wide range of models, thanks to which professional and home craftsmen can purchase reliable, universal devices in accordance with their preferences, wishes and financial capabilities. The most common types include the following models:

The neon lamp voltage tester is a simple pin type indicator screwdriver model. The operation of the device is based on its glow after electric current hits the tip of the device from the surface of the conductor and then passes through a resistance resistor. The second contact in the neon light switching circuit is the end part of the handle. Its closure occurs on a person. The glow of a neon lamp after pressing the end part of the indicator handle with a finger indicates the presence of a phase on the contact of an outlet, switch, household appliance or other power source that needs to be repaired. Contact with the master ensures that the indicator lamp turns on. A high voltage indication threshold of 60V is one of the disadvantages of screwdrivers. They are recommended for determining the phase of an AC electrical circuit. With their help, the technician will not be able to detect open circuits.
The indicator tester with an LED lamp has a low voltage indication threshold. Its identification in the electrical circuit occurs at values less than 60V. The operation of the device does not differ significantly from the operation of analogues with neon lamps.
An indicator screwdriver with an LED and batteries belongs to the category of non-contact multifunctional devices. A voltage probe of this type is supplemented with a bipolar transistor and is recommended for determining the phase wire, places of electrical circuit breakage, and the polarity of direct current sources. A tester with an LED and batteries makes it possible to find the location of wiring in the walls of rooms under a layer of finishing coating.
An electronic type probe with a display and a sound signal belongs to modern models of voltage indicators. Working with the compact device is easy. If you have questions about using an electronic screwdriver model, the manufacturer's instructions will come to your aid. It is included in the package of the multifunctional voltage indicator.

The use of an electronic screwdriver is no different from the use of other analogue screwdrivers intended for safe repair of electrical networks, devices, and equipment. Practical determination of voltage, fault locations of sockets, switches and other power sources using a multifunctional device can always be seen in videos on the Internet. By knowing how to use an indicator screwdriver, you can always avoid electrical shocks, the effects of which pose a danger to human health and life.

Varieties

Most often, there are single-bar indicators of several types on store shelves. There are the simplest screwdrivers with an indicator inside, which is a simple neon light bulb, screwdrivers with additional batteries (usually batteries), and test screwdrivers that have several useful functions.

We have already talked a little about simple screwdrivers. Now let's look at their design in a little more detail. At the end there is a metal part called a probe. Inside there is a resistor, as previously mentioned, followed by a neon indicator, and all this is wrapped in a simple plastic case.

You already know how to use this type of voltage indicator. The range of their use is very limited, but it is more than enough for simple everyday tasks. They are as simple as possible, do not have additional batteries inside, and are particularly reliable.

Next are screwdrivers with indicators, inside of which there are batteries and additional LEDs. In terms of appearance, they are very similar to the first client. The only difference is that it is not necessary to touch the contact plate.

This screwdriver is good because it can find breaks in wiring. This is done very simply - take the indicator, apply the tip to one end of the wiring, take the other end with your hand, and then touch the sensor on the screwdriver. Personally, not so long ago such a screwdriver really helped me out. The wiring that goes from the outlet to the wall light needed to be replaced. Having gouged the wall, I pulled out the old wire and was about to install a new one, but I decided to check it again. It turned out that there were holes inside and the wire was shorting.

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Agree, it would not be very pleasant to discover problems after everything has already been puttied again. This is not to mention the possible problems that such a wire could cause. Which voltage indicator you choose is up to you, but I am sure that this will not be out of place in your tool case. They are a little more expensive than simple screwdrivers, but their price is still quite low.

Next up are modern screwdrivers with indicators. They differ in a certain abundance of possibilities and more sophisticated internals. According to the principle of operation, they are no different from the first two. They have a fairly high level of sensitivity, which allows them to detect wiring without contact, find the phase through a thin wire wrapper, and determine the voltage in the wire.

Sometimes, not always, but sometimes this is a very useful feature. The price tags for such screwdrivers are not at all steep, they work accurately, and in terms of use they are as simple as the first two options.

Where to use this? Again I will give an example from personal experience. Last year, the repair crew damaged the power cable for the TV and peripherals, which was thrown from the outlet and covered with a layer of plaster. The apartment is in an old building, so the wiring is not very well thought out, but I didn’t want to completely re-install it. Therefore, I made a branch that goes from the outlet and reaches the right place, and a power point is organized there. So it stopped working after cosmetic repairs.

The socket from which the branch comes was normal, so I thought about the wiring. I started drilling small holes in the wall and checking the cable, using a non-contact voltage indicator for this. I was ready to open the wall and get all two meters of cable. Through two holes I saw tension. It turned out that 20 centimeters from the new outlet, while installing the shelf, the would-be builders started making a hole in the wrong place and damaged the wire. For some reason they decided not to tell me about it, and they simply sealed the hole and hung the shelf higher. If it weren't for this screwdriver, a week after the repair, I would have started a new one again.

Rules for choosing a hidden wiring indicator

Models of hidden wiring indicators, for the most part, guarantee the functionality described in the instructions.

When purchasing a detector, keep the receipt, packaging and warranty card. If the device does not work, you can always exchange it for a more suitable model with an additional payment.

However, there are features of choice that the average person does not think about when purchasing specialized electrical equipment.

They are listed in the form of a list of rules:

The physical parameters of foreign power grids may differ greatly from domestic ones, so you should not buy power supply systems that are not certified under national legislation.
It is necessary to take into account the material of the walls in the place where the device is intended to be used and the depth of the wiring.
When determining the locations of inactive wiring, devices with metal sensors are needed.
After purchasing the device, it is advisable to check its performance in the store. The detection depth can be assessed by covering the cable with a ceramic tile, wooden board or sheet of foam.
Due to their simplicity of design, budget models can be more durable than ICPs with complex electronic circuits.

When purchasing a hidden wiring detector, you should definitely consult with the seller, because if you choose on your own, there is a high probability that the purchased equipment will not fully meet the tasks assigned to it.

The following photo selection will introduce you to the detector models that are in demand on the market, allowing you to accurately determine the position of the hidden wiring route:

Design and method of application

Design features and mechanism of action are worth considering in more detail for some species.

Single-pole indicators are equipped with one pole, with the help of which the voltage in the electrical network is determined. How to check this voltage? To do this, you need to touch the current-carrying part of the device with the pole.

In this case, the process of closing with grounding occurs directly through the human body at the moment it touches the contact located on the pointer with a finger. The current at this moment is not significant, practically minimal, about 0.3 milliamps, but the light bulb, however, turns on.

Inside the case there is a resistor and a neon light bulb, and its lower part is equipped with a spring and a probe, while the upper part has a platform for contact with the finger upon contact.

A single-pole device is designed to test exclusively alternating current, because with constant current, a neon light will not appear (the lamp will not turn on), despite the presence of voltage. Most often, such a device is used to check the phases of cartridges, switches, sockets, etc.

Without personal protective equipment, in particular without protecting your hands with rubber gloves, you can use the pointer at voltages up to 1000 volts. In accordance with electrical safety rules, it is prohibited to use a test lamp that is inserted into a socket with pieces of wire attached to it. As a result of a sudden increase in voltage in the electrical network, the lamp bulb will rupture, which can lead to injury to the electrical network worker.

The disadvantage of a single-pole device is low sensitivity and voltage detection only up to 90 V.

Use of control devices

Before each use, the indicator is inspected for damage to the housing or insulation, after which the functionality of the indicator is checked by touching a phase that is known to be energized. A defective device will cause an error resulting in a short circuit or personal injury. When taking measurements, you must be careful and follow the basic rules:

the indicator must correspond to the network parameters - it would be useful to verify this by looking at the markings on the device body;
during the check, take a stable position, excluding unexpected falls and contact with grounded conductors;
One way to avoid unwanted contact is to keep your free hand in your pocket so you don't accidentally create a closed circuit for electrical charge.

When working with a single-pole indicator, it is prohibited to use dielectric gloves: contact of the plate on the indicator handle with the operator’s finger must be ensured. We must remember that electricity is dangerous - not only beginners, but also experienced installers die from mistakes.

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Areas of application of indicators

The scope of application of the IPS depends on the configuration of the device and its sensitivity.

Basic models of combined detectors can be used for the following purposes:

identification of hidden electrical wiring in ceilings, walls, floors;
detection of electrical cable breaks;
correct connection of electric meter phases;
determination of phase wire;
detection of ungrounded equipment;
checking the serviceability of fuses and fuses;
detection of locations of metal reinforcement in the wall,

Additional features of the ISP include the following functions:

indication of objects of the types “non-metal”, “non-magnetic metal”, “magnetic metal”, “live wiring”;
determination of surface temperature;
indication of detection accuracy as a percentage;
tree detection;
automatic detection of the center of metal objects.

You need to think about the required functionality before purchasing a detector, because the price of devices with minimum and maximum components can differ by 50-100 times.

Indicators with a universal device

Sometimes electricians need to “ring” a network, and then they use universal indicators. They have a large capacitor capacity, which acts as a voltage source. If other devices often use neon lamps, here the presence of current will be shown by LEDs.

Advanced users stick out devices with displays where the voltage value is indicated. Most often, universal devices operate on batteries.

Another way to find out about the presence of current is to study the electromagnetic field, and indicators hidden in the rooms cope with this task. When changes occur, they signal with color and sound.

Description and principle of operation

A high and low voltage indicator is a portable universal device that is designed to determine the voltage on live wires or terminals of individual electrical devices. The following voltage indicators are considered the most common today:

UVN 10.
UNK.
UVNK-10.
BN-020022 Profipol Benning.

Voltage indicator with display

A voltage indicator is necessary when working at various enterprises or when electricians travel to the site. The main difference between a voltage indicator and standard meters is that it can only determine the presence of a load, but not its indicators. Basically, the most common are voltage indicators up to 1000 Volts.

Such products can be single-pole or double-pole. They have a common scheme, but the scope is different. When operating a device with two poles, it must be connected to two current-carrying conductors or contacts. A single-pole indicator, in turn, should be connected to only one core. To obtain more accurate indicators, it is necessary to use two-pole indicators. They are called high-voltage and are used in the process of carrying out complex work.

UN PIN-90

In addition, you can also find a contactless pointer in specialized stores. The voltage test will be carried out without connecting to live contacts. This significantly increases safety in the voltage determination process. On such devices you can find a digital display. It indicates not only the presence of voltage, but also the approximate size.

Single-pole voltage indicator HT20

You can also find portable models that run on batteries or those that require a power connection. Such voltage indicators include the following devices:

Contact 55EM.
UVNU-10 kV SZIP.
ELIN-1-S3-VL.

When choosing portable devices, power will be provided using 2 or more batteries. In models UVNK, UNNO, UNK, EI-9000/1, Duspol digital LC, Raton, power is provided using a battery. This allows you to use the device on the go, if the power supply network is located far away.

The operating principle of such devices is quite simple. When connected to the network, potentials are compared. This increases or decreases the resistance in the pointer resistors. As a result, the indicator, which consumes small fractions of amperes, lights up or makes beeps. If the indicator in the voltage gauge is silent, then this means that there is no load. In some situations, signal attenuation may be observed. This indicates that there was residual energy in the wires.

General information about indicators

Potential detection devices on current-carrying network elements operate on various principles related to the properties of electricity. Low voltage indicators are manufactured in accordance with the action of a certain quality indicator. There are standards that define the requirements for control devices.

Operating principle

Inside every object there are electrical charges: cations, anions, electrons. Their number determines the magnitude of the positive or negative potential. The difference in the values of this indicator is the voltage, the formation of which in a closed circuit causes the movement of charges - electric current. This property is used when creating devices for detecting potential:

a resistance is installed in the path of the particles, reducing their concentration to a minimum safe for humans;
the remainder of the electricity is converted into magnetic, light, sound energy;
Based on the intensity of the received signal, one judges the presence or absence of potential on the conductor.

A contact or two terminals of the device are connected to the network elements and the presence or absence of current is verified. The available voltage will be indicated by the sound of the built-in microspeaker, an LED light or the arrow of a measuring device.

Product classification

Knowledge of the range of industrially produced devices will help you select the most suitable low voltage indicator for your conditions. The division of modifications occurs according to different criteria. Manufacturers offer designs in the following categories:

Depending on the type of current being measured - for operation in DC or AC voltage circuits.
According to the number of operational contacts - single- and double-pole. The latter are universal; they are used to determine the potential in any circuit. The principle of their operation is based on the passage of active electrons. The first type of indicators has a different device - single-pole ones: they use the properties of capacitive current, and use devices only in alternating networks.
In connection with live parts - contact and non-contact, allowing you to detect voltage indirectly without touching the network element. An example of the latter type of devices are Chinese-made indicators: MS-8 and 58. They consist of an LED, radio components and are powered by miniature batteries, the non-contact measurement range is 70–600 V, polarity detection is 1.5–36 V. For inexperienced craftsmen, such an indicator It’s better not to use it: it reacts to all surrounding objects.
Depending on the type of indicator - digital and LED.

There are differences in devices in terms of measurement range and appearance. The voltage allowed for operation is marked on the device body. Using a 220 Volt indicator on a 0.4 kV network is dangerous to life.

Manufacturing requirements

Voltage indicators up to 1000 V are subject to certain conditions that are mandatory for device manufacturers. The full list of requirements is set out in the state standard. The most important conditions are the following:

light and sound signals are clearly recognized, the interval between pulses lasts no more than a second, the load on the indicator is up to 50 V;
the single-pole pointer is enclosed in 1 housing, on which there is an electrode tip, and on the handle there is a contact for the operator’s finger;
Bipolar devices have 2 separate shells connected by a meter-long wire and each equipped with a working electrode with an open tip of up to 7 mm.

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Voltage indicators can combine other functions - searching for a phase conductor, checking the integrity of the network, establishing polarity. The condition for expanding the capabilities of the device is maintaining the safety of use for its main purpose. Before starting work, the indicator is checked with a potential of 2 kV, turned on for a minute.

In some cases, preference is given to bipolar voltage indicators, and the safest is considered to be non-contact - it reads information through a magnetic field. When checking for potential, the connection between the pointer and the current-carrying element is maintained for at least 5 seconds.

Two-pole voltage indicator

This type of pointer has two parts, separate from each other. They are made using a dielectric material and an insulated flexible copper conductor that connects two separate parts.

The operating principle of a two-pole indicator is completely simple; you just need to lightly touch the conductive parts with the poles and the device will show whether there is voltage or not.

The current flowing through the lamp is only a few milliamps, but this is quite enough for a stable light signal. To prevent an increase in voltage in the lamp, you need to connect a regular resistor to it.

In addition to the manufactured indicators, you can use similar devices - indicators, which also serve to determine the voltage in the electrical network and are equipped with a special scale backlit by LEDs on the body and calibration of certain voltage readings from 12 to 750 V.

Indicator circuit

The operation of the device is based on the initial turn-on voltage of the LED. Any LED is a semiconductor device that has a voltage limit point, only exceeding which it begins to work (shine). Unlike an incandescent lamp, which has almost linear current-voltage characteristics, the LED is very close to the characteristics of a zener diode, with a sharp slope of the current as the voltage increases. If you connect LEDs in a circuit in series with resistors, then each LED will start to turn on only after the voltage exceeds the sum of the LEDs in the circuit for each section of the circuit separately. The voltage threshold for opening or starting to light an LED can range from 1.8 V to 2.6 V. It all depends on the specific brand. As a result, each LED lights up only after the previous one lights up.

Types of voltage indicators

Voltage indicators are:

with neon lamp;
with LEDs, battery operated;
with liquid crystal display;
contactless;
multifunctional.

Signs with neon lamps are the cheapest

. Their disadvantages are low ignition voltage and insufficient brightness. In bright light, you have to cover them with your hand to see if the lamp is glowing.

LED indicators have a lower ignition threshold.

The presence of a battery allows you to use them to “test” circuits and use the pointer as a contactless one. If you take the tip of an indicator screwdriver and bring its end to a live wire, the light will light up. But if it does not light up, this will not be evidence of a lack of voltage.

The disadvantage of LED indicators is that they glow due to interference in the circuit being tested, showing a “phase” where there is none.

A common drawback of neon and LED signs is the presence of a spring, which weakens over time. The contact inside the indicator is broken and it stops working.

Indicators with displays and non-contact voltage indicators do not have this drawback. For indicators with displays

Same sensitivity as LED. But they recognize interference in circuits, indicating on the display a voltage value lower than 220V. But their readings are not visible in the dark.

Contactless signs are battery operated.

If you turn them on and bring them to a phase conductor, they emit light and sound signals. This is convenient when checking the complete absence of voltage, but is not applicable in cases of determining the “phase” on conductors located close to each other. For this you need a contact pointer.

Multifunctional indicators

are a multimeter that combines the functions of an ohmmeter, voltmeter and non-contact pointer.

Each of the pointers has advantages and disadvantages. When choosing a voltage indicator for your own needs, remember: a good indicator is the one you use. The main thing is to learn to correctly understand the pointer signals.

Passive screwdriver - voltage indicator

The only function of such an indicator is to determine the voltage on a section of electrical wiring or equipment contacts. The standard index consists of two working parts. One of them is a flat-head screwdriver that makes direct contact with live parts. The second part is built into the screwdriver handle and creates the necessary resistance.

You can understand how to use the indicator using the example of a regular electrical outlet to which the phase and neutral conductors are connected. To determine the accessory, you need to press the contact located at the top of the handle with your thumb. After this, you need to touch the socket contacts with the working part of the screwdriver one by one. There is voltage on one of them, which will be immediately signaled by the indicator, lighting up orange or red inside the screwdriver. There will be no reaction to touching the neutral wire.