How and with what you can check the voltage in an outlet. Does the outlet always show voltage when measured with a multimeter, and what is the best way to check the current?

Every consumer faces the difficulty of checking the voltage in an outlet with a multimeter. These measurements are necessary to control the voltage in the network. This observation applies when using powerful electrical equipment at home and in production. If there is insufficient voltage in the electrical network, then stabilizers should be used to normalize this indicator, as well as for the correct operation of electrical appliances.

Multimeter

In order to make a measurement it is necessary to perform some manipulations. In this case, safety precautions must be observed, otherwise you may even get an electric shock.

Peculiarities

The device in question combines several devices that connect differently to one section of the circuit.
In order to use it correctly and get a complete picture of the state of the electrical network or an individual outlet, you should know at least some theory. At a minimum, you should understand how you can measure voltage, and how exactly you can measure current, and how you can correctly connect this or that device. When the cables are connected to a working power source, they receive an electrical voltage measured between zero and phase. To put it simply, it’s “– + “and” – “. The voltage in a standard electrical network can be measured both without a load connected to the electrical network and with it present.

There may also be a ground connection in the outlet.

But the current itself appears only when the circuit is closed. Only after this does it begin to strive to move between the poles. In this case, measurements should be carried out exclusively when the device is connected in series. To measure the magnitude of the current, you should first let it pass through the multimeter.

To ensure that the multimeter itself does not distort the current strength and displays the most accurate data, its resistance should be kept to a minimum. If it is set to the current measurement mode, and at the same time you try to measure the voltage with it, then the result will be a simple short circuit. Although modern models do not have this problem, and voltage and current measurements are made using the same terminal connection. But it won’t hurt to remember some knowledge from the physics course. According to them, the same voltage will be observed in sections of the electrical circuit connected in parallel, and the current strength will be the same only when the conductor connection is in series.

In order to avoid errors and inaccuracies, before starting measurements, you should analyze the markings on the contacts of the multimeter and the mode switch. Note that in domestic conditions several groups of electrical networks are used . The most commonly used system in modern homes is a system with a voltage of 220 volts at a frequency of 50 hertz. Usually it consists of two elements - zero and phase. And the outlet itself plays the role of an exit.

In recent years, in newly built houses, a different power supply circuit has been installed - three-phase. Its difference will be a higher voltage at 380 volts. This makes it possible to power more powerful devices that do not work correctly in traditional systems. At a minimum, for this reason, the rated voltage in the outlet should be measured in order to simply understand whether it is possible to connect some powerful device to the outlets and the wiring capabilities to withstand the load created by the device.

In addition, voltage measurements will be required in other cases:

if you need to check the operation of power cables;
if it is necessary to check the functionality of a switch or socket;
if the light bulb in the chandelier does not light up, although it is known that it is operational.

The ability to use a multimeter yourself will be an excellent opportunity to save on calling a technician.

And if there is information about unstable power supply, it will be possible to protect household appliances from failure by purchasing voltage stabilizers.

Basic principles of current measurement

The main feature of working with a multitester in ammeter mode is that it must be included in the open circuit. This connection is called serial. In fact, the device becomes part of this circuit, that is, all the current must pass through it. And as you know, the current strength in any section of an unbranched electrical circuit is constant. Simply put, how much “goes in” is how much must “go out”. That is, the location of the serial connection of the ammeter does not matter much.

To make it clearer, below is a diagram that shows the difference in connecting a multimeter in different operating modes.

Differences in the principles of connecting a multitester in different measurement modes

So, when measuring current, the multimeter is connected to the open circuit, becoming one of its links. That is, there will be a problem of how to practically organize this circuit break. They solve it in different ways - this will be shown below.
When measuring voltage (in voltmeter mode), the circuit, on the contrary, is not broken, and the device is connected in parallel to the load (the section of the circuit where the voltage is required to be determined). When measuring the voltage of a power source, the probes are connected directly to the terminals (socket contacts), that is, the multimeter itself becomes a load.
Finally, if resistance is measured, then the external power source does not appear at all. The contacts of the device are connected directly to a particular load (the section of the circuit being called). The required current for measurements comes from the multitester’s autonomous power supply.

Let's return to the topic of the article - current measurements.

It is very important to initially correctly set the measurement range on the multimeter, in addition to direct or alternating current. I must say that beginners often have problems with this.

Current strength is an extremely deceptive quantity. And it’s as easy as shelling pears to “burn” your device, or even cause big trouble, by incorrectly setting the upper measurement limit.

You should start measuring current strength, especially if you have no idea about its possible value in the circuit, from the maximum range of the multitester. If necessary, you can rearrange the wire and successively lower the upper limit to reach the optimal one.

Therefore, a strong recommendation is that if you do not know what current strength is expected in the circuit, always start measurements with the maximum values. That is, for example, on the same DT 830, the red probe should be installed in a 10 ampere socket (shown in the illustration with a red arrow). And the operating mode switch knob should also show 10 amperes (blue arrow). If measurements show that the limit is too high (readings are less than 0.2 A), then in order to obtain more accurate values, you can first move the red wire to the middle socket, and then the switch knob to the 200 mA position. It happens that this is too much, and you have to use a switch to reduce it another level, etc. It’s not entirely convenient, we don’t argue, but it’s safe for both the user and the device.

By the way, about safety

Safety precautions should never be neglected. And especially if we are talking about dangerous voltages (and mains voltage 220 V is extremely dangerous) and high currents

We are calmly talking about amperes here, but meanwhile, a current no higher than 0.001 ampere is considered safe for humans. And a current of just 0.01 ampere passing through the human body most often leads to irreversible consequences.

It is recommended to carry out current measurements, especially if work is carried out in the highest range, as quickly as possible. Otherwise, the multitester may simply burn out.

By the way, warning signs near the test lead connection socket can also inform you about this.

An example of a warning notice at the wire connection socket for measurements on the maximum permissible current range

Note. The word “unfused” in this case means that the device in this mode is not protected by a fuse

That is, if it overheats, it will simply fail completely. The permissible measurement time is also indicated - no more than 10 seconds, and even then no more than once every 15 minutes (“each 15 m”). That is, after each such measurement you will also have to take a considerable pause.

To be fair, not all multimeters are so “picky”. But if there is such a warning, you should not ignore it. And in any case, measure the current strength as quickly as possible.

Preparatory stage

Before you check the voltage in the outlet using a multimeter, you should do some preparatory work. To calculate voltage in different cases, different methods of supplying current in devices and systems are used. For example, there is alternating current in the outlet. At the same time, in accumulators or batteries the current is constant. For this reason, testers provide different operating modes. Before you start working with a certain device or system, the device must be switched to the desired mode.

Additionally, each instrument will have a specific flux in voltage measurement . And if this characteristic is unknown in advance, then the lever should be moved to the maximum position. You should also recall the purpose of the connectors located on the multimeter. The “10ADC” connector is needed to determine the DC current characteristics. The maximum allowed value is then 10 amperes.

Only the red probe is inserted here, that is, a plus.

The connector with the word "COM" is generic. Only a black probe, that is, a minus, is connected here to carry out measurements. The “VΩmA” connector is intended for various types of measurements. We are talking about resistance, voltage, current.

To carry out the work, the correct wire connection must be made. The red probe is connected to “VΩmA”, and the black one to “COM”. After this, you should move the control lever to the desired operating mode. To find out the voltage, the lever must be set to the abbreviation “ACV” or “V~”. Moreover, the position of the wheel should be set so that it is at a mark that will be higher than the expected voltage. For a regular power point, the standard is usually 220 volts. That is, it is necessary to set the nearest larger value. For most tester models, this value is 750 volts.

If the user does not even know the expected voltage and it is higher than the specified value, then this can lead to problems. The minimum would be failure of the multimeter, and the worst would be burns to the user’s hands. So before making the necessary measurements, it is better to calculate the network parameters.

Measuring current and voltage with a multimeter

Knowing how to use a multimeter, you can consider the question of how to make measurements depending on the quantities being measured. After all, measuring current in a socket is very different from measuring voltage. In addition, we will consider other possible options for measuring these quantities in everyday conditions.

Measuring voltage with a multimeter

Let's start by considering the question of how to measure voltage with a multimeter in an outlet? This procedure will help you answer the question of whether the network parameters comply with the standards and whether it is possible to connect a certain electrical installation to it.

To do this, first of all, install the probes in the appropriate sockets. In our case, this is the “COM” socket for the black probe and the “VΩmA” socket for the red probe.
Now we make the necessary switches on the multimeter itself. Since the current in the outlet has a variable value, it is necessary to set the ACV limit.

The switch position should be higher than the intended voltage. That is, for a socket that should have 220V, you should select the nearest higher value. If we take our multimeter, we select a value of 750V. For two or three-phase sockets, the nominal voltage value is 380V, that is, we also choose a position of 750V.

Note! If you do not know the expected value of the supply network, then it is better not to measure with a multimeter. If the voltage is higher than the maximum value, in our case 750V, then in the best case the fuse of the multimeter may burn out, and in the worst case it can result in injuries and burns. Therefore, before making measurements, decide on the expected voltage value.

Once the measurement limits have been set, you can proceed directly to measurements. To do this, we insert the probes into the power contacts of the socket and ensure reliable contact between them.

Standard indicators of the home electrical network

Before checking the voltage in the outlet with a multimeter or using the same device to find out the current strength in the extension cord, it is important to know what parameters to focus on for comparison.

The main indicators of the home electrical network are presented in GOST 32144-2013. Moreover, in addition to data that is incomprehensible to the average user (deviation from frequency, non-sinusoidal oscillations, lack of voltage symmetry in a three-phase network), it also indicates more understandable things:

powered by alternating current with an oscillation frequency of 50 G;
standard voltage and its permissible deviations - for residential and public premises for non-industrial purposes, 220 V is accepted with a permissible deviation of up to 10%, for more powerful consumers - a three-phase network with a voltage of 380 V;
permissible rated current in the consumer - 6, 10, 16, 25, 32 A. Sockets and switches designed for a current of 6...16 A are intended for domestic purposes, 25 A - for devices with high energy consumption, 32 A - for three-phase circuits industrial value.

In this case, in the simplest ways - by plugging the device into a socket, turning on a toggle switch - you can only establish the presence of current in the network, but not the magnitude of its strength and voltage. The so-called “probes” also work—screwdrivers with a light or sound indication that is triggered upon contact with active wiring.

For a more detailed and competent study of the state of the electrical network, special multifunctional devices are used - multimeters.

How to use a multimeter?

Before measuring the voltage in an outlet with a multimeter, let's figure out how this device works. We’ll also look at the quantities it can measure.

Multimeters can be analog or digital. The answer to the question of which one is better is obvious - a digital device. After all, digital multimeters always indicate the exact value of the measured value, are tolerant of incorrectly connected probes, and are not so demanding on operating conditions. At the same time, there is only one argument in favor of analog devices - price.

That is why in our article we will look at a digital multimeter. Let's start our review with multimeter probes. To connect them, a conventional device has two or three sockets.

The black probe must be connected to the “COM” socket , which is negative or ground. It depends on the quantity being measured.

The red probe is connected to one of the two remaining sockets . The abbreviation “VΩmA” means that this socket is designed to measure voltage, resistance and current, but only at small values. To measure a current of 1A or more, use a 10ADC socket, which has a more powerful contact part.

Now let's talk about the quantities that a regular digital multimeter can measure. The designation of some quantities may differ among different manufacturers, so we will present all possible options.

To measure DC voltage, the limit designated DCV should be used. Within this limit there are usually several positions for voltage measurements from 200mV to 1kV. To measure AC voltage, use the limit designated ACV. It usually also has several positions for measurements from 100V to 1000V.
The DCA limit is intended for measuring currents. It also has several positions of several hundred microamps, up to several hundred milliamps. In addition, there is usually a provision for measuring current up to 10A. But to connect the device to this position, the instructions advise moving the red probe to the appropriate socket. This is necessary so that the current of 10A is quite large and the weak contacts of the “VΩmA” socket will simply burn out from it.
To measure the resistance of a circuit, we have a limit "Ω". It has several positions for measuring values from 200Ω to 2MΩ.

Note! Any quantity can be measured using a larger limit. For example, a voltage of 100V can be measured not at the 200V position, but at the 1000V position. But as the measurement limit increases, the instrument error also increases. In this regard, the obtained measurement results may not be reliable enough.

In addition to these basic quantities, many devices have additional limits for measuring the current gain of the transistor, testing for short circuits, measuring diode parameters, and some others. These limits are already more narrowly focused and we will not consider them in more detail.

How to check voltage with a multimeter

The thematic article “How to use a multimeter: detailed instructions for beginners” will help you understand the general principles of operation of the device. Here we will talk about using the device to work with sockets and other household electrical appliances.

The simplest multimeters used for household needs “can” measure current, voltage and resistance for AC and DC devices. If you need to check the voltage in a 220 V socket with a multimeter, the device regulator is set to the “alternating” voltage measurement area, marked V~ or ACV (depending on the multimeter model). In this case, taking into account the possible excess of voltage in the network of standard indicators, the regulator is set to the maximum value - 750 V. After turning on the device, the display should show three zeros (depending on the number of digits of the device - there can be from 2.5 to 8.5 - the number of zeros may differ).

Next you need to connect the probes. They are mounted like this: black in a socket marked COMMON (COM), red - or in a socket marked VΩmA.

Important: to make it easier to navigate the symbols on the front panel of the multimeter, we recommend studying the standard marking options.

The probes are installed in both sockets of the socket. The display will show the AC voltage value at that point in the network. If, when asked how to measure the voltage in a socket with a multimeter, the user is “stuck” on the choice of which hole to insert which probe into, we can reassure you. This is not important; in most modern instruments, the polarity of the probes when measuring voltage is not important.

Important: if you need to clarify how to measure the voltage with a multimeter in the socket of a low-power extension cord or in an old, Soviet-style electrical network, you can install the positive probe in the socket marked mA. In this case, overloading the device is practically eliminated.

How to measure voltage in an electrical outlet with a multimeter

A multimeter is a universal device that can be used to accurately determine voltage and current. The device is widely used by electricians and is also often used at home. Every novice user should know how to measure the voltage in an outlet with a multimeter.

What parameters can be measured with a multimeter

This hand-held measuring device is designed for various electrical tests.

A multimeter is a multifunctional device that can be used to determine the following technical parameters:

voltage – constant and variable;
resistance range;
capacity;
frequency;
inductance;
direct and alternating current strength;
temperature regime;
transistor gain;
checking diodes and transistors;
calculation of electrical resistance with transmission of a signal of reduced circuit resistance.

Many models have a knob on the front panel that helps you change values.

Some multimeters have additional equipment and can measure mass, footage or time in seconds

The measurement results are visible on the built-in monitor. On the side of the device there are two sockets for probes - red (positive potential) and black (with negative potential).

Functional elements of a multimeter

Modern manufacturers produce various models of multimeters. Digital instruments with various additional functions, which are considered more accurate, are widely popular. An error of up to those percentages is considered normal. The lower the deviation indicator, the more reliable the test check.

Even the simplest electrical measuring device is capable of determining the most standard values - current, voltage and resistance. More expensive multimeters are equipped with special sensors for measuring temperature. Also, using such a hand tool, capacitance, intervals between pulses, frequency and inductance are determined.

Among the functional capabilities of the multimeter are:

Recognition of disturbances in the operation of an electrical circuit. The device is capable of detecting the resistance value, which has fallen below the required scale, using a sound signal - “diagnosis”.
Checking semiconductor elements. Using a multimeter, you can check diodes, transistors or thyristors, namely their serviceability.
Many advanced models are equipped with displays that receive a signal and can carry out the necessary calculations.

The most popular additional features are:

recording of the detected value by the device - push-button or automatic;
illumination of indicators on the screen;
power failure counter;
reboot indicator;
automatic detection of measurement boundaries.

In professional models, the minimum accuracy error is established. Sometimes digital processing ability is used. The necessary maximum parameters are fixed in the working memory, with the help of which the device calculates the average value.

Also on the front side of the multimeter there is a “continuity” icon and a knob for switching ranges

Almost all multimeters have catchy symbols that display the functional elements of the device:

“DCA” – direct current measurement;
“Ω” – resistance icon;
“ACV” – constant voltage indicator;
“DCV” is a designation for alternating voltage.

Some electrical measuring devices have two indicators at once - digital and dial. To make it easier to work with the device, two measuring scales are used, which allow you to measure in different values.

How to measure the voltage in an outlet with a multimeter - instructions

Even a beginner can check an outlet using a multimeter. You can use either an analog device or a digital device. Measuring voltage is not difficult, based on a detailed description of step-by-step actions:

Turn on the power supply to the 220 V outlet. To do this, you need to find a circuit breaker.
Connect the probes to the tester. The black one goes into the socket marked “COM” or a small “-” symbol, and the red one goes into the socket marked “VΩ” or the “+” symbol.
Press the button that turns on the multimeter. Typically, such a switch is designated “ON/OFF”.
Turn the knob on the front panel of the device in the direction of the AC scale and fix the voltage of 220V, corresponding to the indicator in the socket. Typically, multimeters have a designation of 200V and a final 600V or 750V. Since there is more than 200V in the socket, it is recommended to set it to the maximum value of 600 or 750V.
When turned on, the device should display a zero indicator. Fixed probes are inserted into the socket openings, and it does not matter which hole the red or black test lead is placed into.
After the probes are set, the operating voltage value is displayed on the screen, which should not exceed the limit of 220 - 240V.
The AC neutral line is checked further. This slot is characterized by an L-shape for all hotspot directions. The end of the red test lead is placed in the hot slot, then the black test lead is inserted into the neutral socket. A value of at least 100V and no more than 120V should appear on the multimeter. After this, the red probe is moved to another hot slot and the same readings are obtained as for the first one - 110-120V.
The probes must be removed from the sockets and the multimeter must be turned off. Now you can connect electrical appliances to the outlet.

Digital multimeter: how to use?

The procedure from the moment of preparation is as follows:

Set the preliminary range of the measured parameter. It is necessary to play it safe and put the switch in a position 10-15% greater than the expected one. In this case, even if it is exceeded, the multimeter fuse will not fail.
Connect the cords to the connectors. Make sure that the red (negative) one is inserted into the socket that matches the type of value being measured. At the same time, the black (positive) is connected to the common COMMON (COM) connector.
Bring the bare ends of the probes to the contacts of the circuit or part being tested. Be sure to hold the insulating layer with your fingers. The black probe is connected to the negative section, and the red one, respectively, to the positive section.
Record the readings shown on the display. If the excess turns out to be excessive, move the rotary switch handle to a position corresponding to a lower range of the measured parameter.

Make sure that the multimeter measures exactly the value that is required in this particular case. Before switching buttons and handles, remove the probes and then touch them again to the bare contacts as described above.

Setting up the multimeter for use

A multimeter is a device designed for quickly and accurately measuring characteristics such as:

the magnitude of direct and alternating voltage;
current strength;
resistance parameters and others.

These devices are divided into analog and digital. In an analog tester, the readings are displayed on the scale with an arrow, which is its main drawback. The lack of fixation of the arrow at the final position makes it difficult to determine the result and makes the device not very convenient for the average consumer to use.

The electronic multitester consists of the following parts:

display;
20-position rotary switch;
sockets for connecting probes.

Setting up the tester consists of correctly connecting the probes and setting the switch in the desired position. Probes consist of conductors with metal rods at one end and plugs at the other.

The black (minus) conductor is connected to the COM connector. The plug of the red conductor is connected to connector V.

Taking into account the fact that the current in the network is alternating, the switch is set to the V~ position, the section indicating the alternating voltage measurement mode. Choose a level higher than 220 volts.

If it is necessary to check the switch with a multimeter, the switch is placed in the resistance measurement section. Next, you need to de-energize the network and connect the probes to the terminals of the element being tested. When the position is on, “zero” should appear; when off, “infinity” should appear. If this does not happen, the switch needs to be replaced.

Is it possible to measure the current in a socket with a multimeter? It is possible provided that the tester is connected to it through a circuit with a light bulb. The switch and the red probe are set to other positions, which we will discuss below.

Multimeter accuracy

For any multimeter, the instructions describe the characteristics, which say how much the measurement result may differ from the actual value. The digit capacity of the indicator matters. For the simplest devices it is 2.5. For precision ones, this characteristic is higher and equal to 8.5. By bit depth we mean the ability to display the result from 0 to 9 in full.

In an example it looks like this. If the digit is 3.9, the tester is capable of outputting data from 0.000 to 1.999 inclusive without switching modes. Otherwise, additional simple setup is required.

But this concerns ease of use. The accuracy of the multimeter depends on the discharge only indirectly. However, the connection is obvious. If you take a device with a bit depth of 2.5, deviations are possible within 10% in the direction of increase or decrease.

For professional work, electronics engineers buy testers with a 4.5 rating. Then the maximum error is only 0.1%. More expensive devices allow you to measure the parameters of the circuit and electrical components with a deviation of 0.01% from the readings displayed on the indicator (screen, monitor). Portable devices have a lower accuracy class than stationary, non-portable devices.

What if it’s not plugged in?..

Typically, all studies of household electrical networks, as already mentioned, are carried out through accessible points - sockets and switches. But from time to time it becomes necessary to check the wiring parameters where either sockets have not yet been installed (dismantled), or for some reason this is inconvenient/impossible. A good example is new buildings with “construction renovation”, where the wiring has just been installed in the apartment and there are no electrical appliances in sight except the meter.

If you need to know how to check the voltage in a 220 V network with a multimeter and still get the correct data, it is important to remember:

the easiest way is to check the data in those places where sockets are planned to be installed or they have already been removed - there are two wires here, when connected to which the required characteristic is determined;
mixing up the probes is not a problem. If the polarity is incorrect, the display will show the voltage value with a “-” sign;
The main safety rule is not to touch the metal parts of the probes with your bare skin when they are in contact with the socket/wiring, and do not connect the probes in this position.

Often, beginners also ask how to check the battery voltage (on the battery) with a multimeter. In this case, the procedure is similar, but you should take into account:

different characteristics of the electrical network and the battery - unlike household wiring, the current in the battery is constant. Consequently, the device regulator is set to the area marked DCV (V-);
compared to the mains, the battery voltage is much lower - 1.5...24 V. Therefore, there is no need to set the regulator to the maximum value of the measured range;
The polarity of the probes also does not matter, but it is easier to connect the red (positive) contact to the positive output of the battery, and the negative (black) contact to the negative one.

External structure and functions

Recently, specialists and radio amateurs mainly use electronic models of multimeters. This does not mean that switches are not used at all. They are indispensable when electronic devices simply do not work due to strong interference. But in most cases we are dealing with digital models.

There are different modifications of these measuring instruments with different measurement accuracy and different functionality. There are automatic multimeters in which the switch has only a few positions - they select the nature of the measurement (voltage, resistance, current) and the device selects the measurement limits itself. There are models that can be connected to a computer. They transfer measurement data directly to a computer, where they can be saved.

Automatic multimeters have only types of measurements on the scale

But most home craftsmen use inexpensive models of the middle class of accuracy (with a bit resolution of 3.5, which ensures an accuracy of 1%). These are common multimeters dt 830, 831, 832, 833. 834, etc. The last number shows the “freshness” of the modification. Later models have wider functionality, but for home use these new features are not critical. Working with all these models is not much different, so we will talk in general about the techniques and procedures.

Structure of an electronic multimeter

Before using a multimeter, let's study its structure. Electronic models have a small liquid crystal screen on which measurement results are displayed. Below the screen there is a range switch. It rotates around its axis. The part on which the red dot or arrow is marked indicates the current type and range of measurements. There are marks around the switch that indicate the type of measurements and their range.

General structure of the multimeter

Below on the case there are sockets for connecting probes. Depending on the model, there are two or three sockets; there are always two probes. One is positive (red), the second negative is black. The black probe is always connected to a connector labeled “COM” or COMMON or that is labeled “ground.” Red - into one of the free slots. If there are always two connectors, no problems arise; if there are three sockets, you need to read the instructions for which measurements to insert the “positive” probe into which socket. In most cases, the red probe is connected to the middle socket. This is how most measurements are carried out. The upper connector is necessary if you are measuring a current of up to 10 A (if more, then also in the middle socket).

Where to connect multimeter probes

There are tester models in which the sockets are located not on the right, but at the bottom (for example, the Resanta DT 181 multimeter or the Hama 00081700 EM393 in the photo). In this case, there is no difference in connection: black to the socket with the inscription “COM”, and red, depending on the situation - when measuring currents from 200 mA to 10 A - to the far right socket, in all other situations - to the middle one.

The sockets for connecting probes on multimeters can be located at the bottom

There are models with four connectors. In this case, there are two sockets for measuring current - one for microcurrents (less than 200 mA), the second for current strength from 200 mA to 10 A. Having understood what is in the device and why, you can begin to figure out how to use a multimeter.

Switch position

The measurement mode depends on the position of the switch. There is a dot at one of its ends, it is usually tinted white or red. This end indicates the current operating mode. In some models, the switch is made in the form of a truncated cone or has one pointed edge. This sharp edge is also a pointer. To make your work easier, you can apply bright paint to this pointing edge. This could be nail polish or some kind of abrasion-resistant paint.

Position of the measuring range switch on the multimeter

By turning this switch you change the operating mode of the device. If it stands vertically up, the device is turned off. In addition, there are the following provisions:

V with a wavy line or ACV (to the right of the “off” position) - AC voltage measurement mode;
A with a straight line—DC measurement;
A with a wavy line - determination of alternating current (this mode is not available on all multimeters; it is not present in the photos above);
V with a straight line or the inscription DCV (to the left of the off position) - for measuring DC voltage;
Ω - resistance measurement.

There are also provisions for determining the gain of transistors and determining the polarity of diodes. There may be others, but their purpose must be found in the instructions for a specific device.

Security measures

Now let's talk about safety measures that you should know when carrying out this type of work. The first thing you should know is to avoid touching the parts with your fingers. The fact is that the human body has resistance, which will affect the accuracy of measurements and can distort them. Another aspect is that if the master does not have information about the pre-voltage in the network, then you can measure the indicators so that the control wheel is set to the highest value in volts.

In addition, it is best to carry out work wearing special dielectric gloves . Although ordinary rubber or household ones may be suitable. When determining line resistance, it is best to ensure that the power is completely turned off and the capacitors are completely discharged.

In addition, when working with a 20-amp power point, measurements should be taken no more than a quarter of a minute. Also, you should not check the network performance with a tester if the room humidity is high . In addition, the control wheel must not be turned under any circumstances while taking measurements. Also, you should not use the device if the braiding of the probes is deformed and there is serious damage to the body.

The battery of the device should be replaced only after the wheel has been switched to off mode. After this, the used battery is disposed of. Under no circumstances should it be thrown away with household waste. When measuring the internal resistance of a circuit, make sure that it is not energized so that the tester is not damaged. There are standards for the operation and storage of such a precision instrument as a multimeter. Do not apply voltage to the device if the rotary type lever is at “Ohm”.

In addition, the device in question should not be used if the housing cover is not securely or completely closed.

An equally important aspect is that replacing a galvanic-type battery should be done not only when the device is turned off, as mentioned above, but also when all probes are disconnected from the multimeter sockets. Measuring the voltage in an outlet with a multimeter is a rather responsible process. The person who is going to carry it out must have certain theoretical and practical knowledge, as well as take into account certain standards and requirements that are put forward for the equipment.

But, nevertheless, with all the necessary knowledge of a theoretical and practical nature, even a person who has never done anything like this before can carry out this type of measurement . The main point will be the correct setting of the expected characteristics of the electrical network, because it is this aspect that most often leads to equipment breakdowns, since users do not pay due attention to it. Therefore, we should once again recall the importance of this particular component.

Possible problems

No device, including a digital multimeter, is capable of displaying incorrect or incomplete data, or not displaying it at all.

Doesn't turn on

If the tester does not show anything, check whether it is turned on at all. Next, check to see if there is a battery in it, and whether it is so discharged that it stops turning on. Check if the display is intact. If the tester is turned on, but with a new battery it does not show anything, the reasons are as follows:

the power cord or terminal has fallen off, the battery is damaged or its contents have leaked;
the device fell, hit, got wet, causing the display to lose contact with the interface module (digital matrix controller);
when exposed to aggressive chemicals, liquid crystals leak out and the reflective film is damaged - the screen becomes not only inoperative, but whitish;
The central microcircuit that controls the operation of the device is faulty.

If you have the necessary repair knowledge and skills, you can disassemble the device. You are quite capable of finding out what is wrong with it. In the latter case, when the ADC (microchip with converter) does not work, the multimeter cannot be repaired. The only exception is the situation when you have another multimeter at hand, in which the screen, buttons and/or switch are damaged.

Exaggerates voltage values

If the battery is low, the device will start to lie. There have been cases when the “outlet” voltage instead of 220-240 V showed, for example, 260-310. This happens when the battery is discharged to 7-8 volts. Replace the battery with a new one and repeat the measurements in the same place. Most likely this problem will be resolved.

The display is too “faint” or “bright”

A slight highlighting of all sectors of numbers against the background of the required ones (for example, number 8 against the background of number 3) is an indicator that you came across a battery with a voltage that accidentally turned out to be higher than 9 V, for example, 10.2). This also occurs when the tester is forcibly powered from an outlet using a 12-volt power adapter, which is an excess. Do not supply power with voltage greater than 9V.

The pale glow of the display sectors (the numbers are barely visible) indicates that the battery is discharged to 6 V, and the multimeter is about to turn off. Change the battery.

Incorrect display of numbers

For example, if instead of the number “8” you saw a capital “L”, “stroke”, “space”, “minus”, capital or lowercase “P” (or “U”, “C”, “A”, “E” ), “soft sign” (all this should not happen), then the display controller has failed. In some cases, the corresponding elements of the digital matrix may be partially damaged.

If you have a working matrix from exactly the same tester in which the “motherboard” burned out or crashed, you can rearrange the surviving display from it and then compare the results. If the same problems are detected, suspicion already falls on the display controller. There is nothing you can do here. Buy a new multimeter.

The beeper does not work in dialing mode

Some multimeters have a button that turns off the beeping of the device when the line is dialed. Make sure the alarm is not turned off. Otherwise, the “beeper” wire has been disconnected from the board, or it is defective or damaged during a previous careless repair of the device. Install a sound emitter from another similar tester. You can work without it.

Backlight doesn't work

If you did not turn off the backlight using a special button or the battery did not run out, then a sign of a non-working backlight may be defective or fallen off LEDs. Check (and replace) them. You can work without backlight.

Slow operation of the device

Slow response of the multimeter to changing conditions, such as connecting other resistors, indicates defective auxiliary parts on its board. So, if the resistance does not change immediately when adding a resistor, in standby mode the last digit “0” changes to “1” and back, then the reason is a malfunction of the capacitors on the device board.

The screen turns on and off

When the screen lights up at startup, but goes out a few seconds after turning on, the problem is in the multimeter’s master oscillator. Since the SG is part of the main microcircuit, you are unlikely to achieve anything here; this element cannot be replaced. The entire device must be replaced.

Why know the voltage in the outlet?

The outlet is carrying alternating current. This means that deviations from the nominal value occur, up or down. The nominal voltage in Russia is considered to be 220 Volts, but in fact the value is 230 Volts. Modern household appliances are created taking into account permissible deviations; exceeding the specification can cause damage to the devices. Devices with electric motors (air conditioners, refrigerators) are especially susceptible to influence. To reduce the risk of breakdown, you need to be able to determine voltage using special testers.

Many people believe that this skill is not necessary for the average user and is only needed by specialists. This is not so, because fixing the socket, checking the presence of a network in the apartment and other work related to wiring begins with determining the voltage.

Measuring current in a socket

Never, under any circumstances, measure the AC power of an outlet with a multitester directly, without a connected load. If you simply insert two probes from the tester into the socket, you can “say goodbye” to the device. As a result, we get “New Year’s fireworks” and a burnt-out electrical measuring device.

The current strength in the socket must be measured with a load connected in series to the “tester-socket” circuit. Even an ordinary light bulb with a socket (the place where the lamp is screwed in) can act as an elementary load.

To correctly measure the current in the circuit, we switch the trigger to the maximum position of the “A~” section; in the presented device this value is 20 Amperes. We move the red probe into the connector labeled “20A” (UNFUSED - mode without a fuse, FUSED - mode with a fuse)

Having connected the tester and the light bulb in series, insert one of the probes into the socket, and connect one wire from the light bulb base to the other probe. We insert the second wire of the light bulb into the free hole of the socket. We take the current values. It is not recommended to measure for more than 15 seconds in time.

And yet, it is not recommended to measure current strength in an outlet. This does not carry any semantic load. The household power supply simply has a maximum limit in Amperes that must be observed. The current strength always exists only in the presence of a load, where we measure the current.

Which wire can you touch in a live socket? Phase or zero?

Since we are in the electrical safety section, we will also discuss the issue of touching the neutral and phase wires in the socket. Electricity will not be disassembled by accident or on purpose, the result will be the same.

We immediately touched the phase and zero

A current flowed through you of the same magnitude as U/R. Where R is your internal resistance, which depends on various factors. That is, the current will flow and you will be sad or posthumous. There are several ways current flows through a person.

Touched the phase conductor:

If you are soaring in the air like a bird or standing on a dry wooden stand, plus you don’t touch grounded objects with other parts of your body, plus a bunch of other factors that you “took into account” (although most likely you didn’t take into account, but circumstances just happened that way) => Then you will not will give you an electric shock.

Note: Let's assume that the situation was such that you survived. And you tell everyone that this is how you can do it. Someone will listen to you and repeat, but with a sadder outcome. Either because of a wet floor or hands, or because of accidental contact with a grounded equipment case. This means that you doomed a person to disaster, only because you used the “survivor effect”. Is not cool.

Touched the working zero:

Nothing will happen to you only if the load in the network is symmetrical in all three phases, and the current does not flow in the neutral wire (more about neutral displacement), and this is a rare case that can sometimes occur in production.

It is always easier to turn off the power and carry out the necessary work than to put your life at risk. As they say, safety rules are written in blood. But I do not deny that there were people who took up the phase and neutral wires and got nothing. Simply playing with electricity will not lead to anything good. It's like walking blindly through an unmarked highway at night.

Personally, I always use the following rule: if you want to tinker with sockets or switches in the apartment, turn off the input circuit breaker and make sure that no one turns it on.

What will it show if the socket is faulty?

If there is no network, the multimeter will read 0 Volts. The reason is a faulty socket or lack of electricity. To determine the cause, you need to ring other outlets in the room. If only one does not work, its contacts are checked and, if necessary, replaced with a new one.

During voltage surges, the values on the multitester will differ greatly from the nominal 220 Volts. According to GOST, a deviation of 10% is permissible; a larger deviation can lead to damage to electrical appliances. If a strong voltage surge is detected, it is worth installing an additional stabilization device in the apartment.

The home network operates at a voltage of 220 Volts, but in the outlet it may differ from the nominal value. Voltage within the limits established by GOST is the key to high-quality and stable operation of household appliances. It is important to be able to check voltage using a multitester to prevent the risk of damage to electrical devices. If there is a significant deviation from the set values, care should be taken to stabilize the voltage in the room.

Difference Between AC and DC Voltage

It would be more correct to talk about the difference between direct and alternating current. Various electrical appliances operate on either direct current or alternating current.

Variable means that the direction of movement of electrons in a conductor changes from plus to minus with a given frequency, that is, the polarity of the current changes. In a household outlet, according to the standard, the effective voltage is 220 V (amplitude 311 V) and the frequency of current change is 50 Hz. All devices that are plugged into an outlet operate from this voltage.

But accumulators and batteries are sources of direct current. They always have a fixed plus and minus (polarity). Naturally, direct current has no frequency.

Measurement of linear and phase voltage

In most private houses, when connected to a 220 V power supply, only 2 or 3 wires go to the meter or electrical panel.

In the first case, the two wires are:

phase;
zero.

In the second case (with three wires) there are:

phase;
zero;
grounding

The presence of 4 or 5 wires at once indicates that there is a connection to a 380 V network. Most often, this voltage is connected to:

office buildings;
production facilities;
garage cooperatives;
trade enterprises;
less often - to private houses.

The voltage between any two of the three phases of the power supply line is called linear, and between any of the phases and zero is called phase voltage. For our country, the standard for linear voltage is 380 V, and phase voltage is 220 V.

To check the phase or line voltage of the electric current in the network, you can use the same instruments that are used to measure alternating voltage:

voltmeter not used in everyday life;
a multimeter, which is used quite often in life;
tester - analogue of a multimeter, only of a mechanical design;
an indicator screwdriver, which any self-respecting owner of a private home cannot do without.

Determining the presence and magnitude of voltage in the network is carried out exactly according to the same scheme as for alternating current.

The most common cause of breakdowns and failure of electrical appliances is manufacturing defects. Operation under incorrect conditions, including unstable mains voltage, is a slightly less common reason. If the refrigerator compressor simply burns out due to voltage surges, it’s not a big problem. It is much worse if this leads to a fire. To protect against such situations, a special device was developed - a voltage relay.

Voltage control relay allows you to maximize the safety of the operating conditions of household electrical appliances

The main purpose of the relay is to automatically connect electrical appliances to the power supply and automatically turn off in the event of fluctuations exceeding the norm or the voltage drops below a certain level. Modern voltage relays consist of an electromagnetic switch and a microprocessor board. Also, sometimes you can still find older devices, the operation of which is based on diodes, transistors and resistors.

The front part of the case is usually equipped with control levers or control keys. Some models also have a display that displays the voltage in real time. Before putting the device into operation, you should set the limited response values (usually from 100 to 400 V). The principle of operation of the device is quite simple.

In real time, the processor determines the voltage value. The relay does not manifest itself in any way as long as the voltage in the network is stable or does not exceed certain tolerances. When the voltage value exceeds the minimum or maximum limit, the relay opens the circuit, de-energizing all electricity consumers. The relay operates in a fraction of a second, which 100% guarantees the reliability of the device and protection against power surges.

Even if over a long period of living in a house or apartment there were no cases of burnout of household appliances, this does not mean that there is no need to control voltage stability. In most cases, the voltage constantly deviates from the norm by a minimum amount, which also negatively affects the operation and service life of the devices.

Connecting home appliances to the electrical network via a relay is carried out for the following purposes:

ensuring protection of single- and three-phase networks;
protection of expensive household appliances from breakdowns;
eliminating the possibility of imbalance or phase loss;
safe operation of installations equipped with electric motors;
network overvoltage protection in public buildings, industrial workshops, apartments and houses.

Measuring AC current with a voltmeter

If you need to measure the strength of alternating current, but you only have a budget multimeter at hand, which does not have such functionality, then you can get out of the situation by using the measurement method using a shunt. Its meaning is reflected by the formula I = U / R, Where I is the current strength that needs to be found, U is the voltage in the local section of the conductor, and R is the resistance of this section. From the formula it is clear that if R is equal to one, then the current strength in the circuit section will be equal to the voltage.

To measure, you need to find a conductor with a resistance of 1 ohm - this can be a fairly long wire from a transformer or a piece of spiral from an electric stove. Wire resistance, i.e. its length is adjusted by the tester in the appropriate test mode.

The result is the following circuit (incandescent lamp as a load):

From the first connector of the socket, the wire goes to the beginning of the shunt, and one of the multimeter probes is connected here.
The second probe of the multimeter is connected to the end of the shunt and from this point the wire goes to the first contact of the lamp base.
From the second contact of the lamp base, the wire goes to the second connector of the socket.

The multimeter is set to AC VOLTAGE MEASUREMENT MODE. It is connected in parallel to the shunt, so all the rules are followed. When the power is turned on, it will show a voltage equal to the current passing through the shunt, which in turn is the same as the load.

Symbols on the device

You can check the voltage with a multimeter by switching the latter to the DC or AC voltage measurement mode. Next to the highest range of measurement of direct and alternating voltage there is an icon in the form of a lightning bolt with an arrow at the end - an identification symbol indicating voltage that is dangerous to life.

The higher the frequency, the lower the limit: experienced craftsmen have noted cases when even audio frequency voltages of up to 40 V, supplied from the amplifier to any of the speakers of hundreds of watts, gave an electric shock. For example, there have been cases of electric shocks with a voltage of 20 V with a frequency of 8 kHz. Be careful when working under voltage of several tens or hundreds of volts: accidentally touching a live part can be fatal for an unprotected beginner.

The following icons are also meaningful:

the symbols “V~” and “A~” indicate alternating voltage and amperage, respectively;
hFE – transistor current amplification factor (indicated in reference books as h21);
speaker or beeper icon – dialing mode (resistance up to 200 ohms, at 50 ohms the sounder is activated);
diode icon – check diodes and transistors without having to remove them from the board;
k – prefix “kilo” (kilo-ohms);
M – “mega” (megaohms);
m – “milli” (most often these are milliamps);
Greek lowercase letter “mu” – prefix “micro” (microamperes);
capital Greek "omega" - resistance in ohms;
F – farads (capacitance of capacitors);
Hz – hertz (current frequency);
degree icon or "temp." marker – air temperature measurements;
DC - from English. “direct current”, direct current parameters;
AC - from English. “alternating current”, alternating current parameters.

The last two markers sometimes replace the dash (direct current) and tilde (alternating current) icons, respectively. It is recommended to remember them - at least those responsible for measuring current, voltage and resistance. Others require special knowledge.

How to Measure Battery or Battery Voltage

All kinds of batteries and various accumulators, in general, everything where you see “+” and “-” are all sources of direct electric current. Measuring DC voltage is no more difficult than alternating voltage.

To do this, take, for example, the most ordinary AA battery. Connect the red wire of the multimeter to “+” terminal of the battery, and the black wire to the “-” terminal of the battery . If you connect them the other way around, nothing bad will happen, the readings will simply be displayed on the multimeter screen with a minus sign, something like this.

Usually the voltage on the batteries is low, so you don’t have to be afraid to press the probes with your fingers. Up to 20 volts you most likely won't feel anything. In the case of an AAA battery, its maximum voltage is 1.5 volts, which is not at all dangerous for a person.

As we can see from the multimeter readings, the voltage in our battery is 1.351 volts, which means the battery is still fully charged and can be used.

In a similar way, you can check any other batteries and measure their voltage, and as you now know, there is nothing complicated about it.

Checking the diode with a multimeter

The diode only conducts current in one direction, so two measurements will be required to check for functionality. In the first position there is conductivity, in the second there should not be. A breakdown is indicated by two cases when the current does not flow in both directions or vice versa, if the readings are zero in any of the cases. When checking, the handle is moved to a position whose range satisfies the nominal characteristics of the diode being tested.

Analogues of the Duwi and KVT socket testers - which is better?

Other manufacturers also have similar testers. For example duwi or KVT MS686ODR.

However, they lack the ability to check voltage. Sockets are tested in the same way.

You plug in the tester and by the flashing indicators you get the information you are interested in. Fortunately, everything on these testers is written in Russian and there is no need to translate anything.

For example, checking the carry.

As you can see, the middle LED is blinking. This means that there is no grounding in the carrier. Unfortunately, this picture occurs all the time. Therefore, when choosing extension cords, be extremely careful.

Unfortunately, the functionality of similar devices from KVT and other manufacturers is slightly limited and they lack a voltage display. And this is perhaps the main thing that interests the average consumer.

You can get acquainted with an adequate price and order such a miracle Habotest tester from our Chinese comrades here.

Tester operating instructions (in English)

As a result

Even a budget universal measuring device - a multimeter - allows you to take measurements within a fairly wide range, sufficient for home use. But when buying a device, you need to at least have a general idea of what purposes it will be used for - it may be better to overpay a little, but as a result, have a tester on hand that can perform any task assigned to it. Also, before using it, it would not hurt to at least in general refresh your memory of the basics of constructing electrical circuits and using electrical measuring instruments in them.

Sources

https://stroy-podskazka.ru/multimetr/proverit-napryazhenie-v-rozetke/
https://stroy-okey.ru/house/instrument/kak-proverit-naprjazhenie-v-rozetke-multimetrom/
https://instanko.ru/instrumenty-i-materialy/tester-elektricheskij-multimetr-instrukciya-2.html
https://electric-220.ru/kak-proverit-naprjazhenie-multimetrom
https://pomegerim.ru/electrobezopasnost/sila-toka-v-rozetke.php
https://domikelectrica.ru/kak-proverit-rozetki-v-kvartire/
https://YaElectrik.ru/elektroprovodka/kak-proverit-napryazhenie-v-rozetke-multimetrom

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