Consider how to measure the voltage and current in the outlet

  1. How to work with a multimeter?
  2. Measurement of current and voltage with a multimeter
  3. Measurement of voltage with a multimeter
  4. Current measurement using a multimeter
  5. Conclusion

Measurements with a multimeter

How to measure the voltage in the outlet or determine the value of the current flowing through it? Such a question became practically before each of us. The answer is quite simple - it is a multimeter, a universal device for measuring a variety of electrical parameters.

The main feature of this device is a combination of a wide variety of devices that may require both professional and homegrown electrics. Moreover, in order to use such a device, one does not need to have any specific knowledge. Suffice it to recall school lessons in physics.

How to work with a multimeter?

Before measuring the voltage in the socket with a multimeter, let's see how this device works. And also we will understand the values ​​that he is able to measure.

And also we will understand the values ​​that he is able to measure

Analog multimeter

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

Digital multimeter

That is why in our article we will consider a digital multimeter. And we will begin our review with multimeter probes. To connect them, a conventional device has two or three sockets.


  • The black probe should be connected to the “COM” jack , which is negative or earth. It depends on the quantity being measured.

Connecting multimeter test leads

  • The red probe connects to one of the two remaining sockets . The abbreviation "VΩmA" means that this socket is designed to measure voltage, resistance and amperage, but only for small values. To measure the current in 1A and more, use the 10АDC socket, which has a more powerful contact part.

Designation of values ​​measured by a multimeter

Now let's talk about the values ​​that a conventional digital multimeter can measure. For different manufacturers, the designation of some values ​​may vary, so we give all possible options.


  • For measuring DC voltage, use the limit indicated by DCV . In this limit, there are usually several provisions for voltage measurements from 200mV to 1kV. To measure ac voltage, use the limit labeled ACV. It usually also has several positions for measurements from 100V to 1000V.
  • The DCA limit is used to measure currents . It also has several positions of several hundred microamps, up to several hundred milliamps. In addition, there is usually a position for measuring the current in up to 10A. But to connect the device to this position, the instruction advises to rearrange the red probe in the appropriate slot. This is necessary so that the current in 10A is sufficiently large and the weak contacts of the “VΩmA” socket simply blow out from it.
  • To measure the resistance of the circuit, we have a limit "Ω" . It has several positions for measuring values ​​from 200Ω to 2MΩ.

Note! You can measure any value with a larger limit. For example, a voltage of 100V can be measured at the position of not 200V, but at the position of 1000V. But with an increase in the measurement limit, the error of the device 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, continuity for short-circuits, measuring diode parameters, and some others. These limits are already more focused and we will not consider them in more detail.

Alternative designations on the multimeter

Measurement of current and voltage with a multimeter

Knowing how to use a multimeter, you can consider the question of how to measure them, depending on the measured values. After all, the measurement of current in the outlet is very different from measuring voltage. In addition, we will consider other possible options for measuring these quantities in the domestic environment.

Measurement of voltage with a multimeter

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

  • To do this, first 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 switching on the multimeter itself. Since the current in the outlet we have a variable value, it is necessary to set the ACV limit.

Switch position for voltage measurement in the outlet

  • The switch position must be higher than the expected voltage. That is, for the outlet in which should be 220V, you should choose the nearest higher value. If you take our multimeter, then we choose a value of 750V. For two or three-phase outlets, the nominal voltage is 380V, that is, we also choose a position of 750V.

Note! If you do not know the intended value of the mains supply, then it is better not to measure with a multimeter. If the voltage is higher than the maximum value, in our case 750V, then at best the multimeter's fuse can burn out, and at worst everything can end up with injuries and burns. Therefore, before making measurements, determine the expected value of the voltage.

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

Measurement of voltage with a multimeter

  • After that, the display of the multimeter will display the instantaneous value of the voltage in our outlet. It may vary slightly within 1 - 2B, this is normal. If it fluctuates over a wider limit, then this indicates unreliable contact between the test leads and the power terminals of the outlet, or poor contact at the electrical network itself.

Determining the price of division of an analog multimeter

  • If you use an analog multimeter, then before you measure the voltage in the outlet, you should decide on the scale division value. After doing a simple calculation, calculate the instantaneous voltage value.

Current measurement using a multimeter

But the measurement of current in the outlet using a multimeter is much more difficult. First of all it is connected with the feature of switching on the measuring device for measuring the current strength.

  • Let's look at what is the peculiarity of connecting instruments for measuring current. The fact is that to measure the current, we should connect a multimeter or an ammeter in series with the electrical installation.
  • That is, in the outlet itself, without a current device connected to it, there is no current. Therefore, we can not measure it. But when you connect the device through the socket, a current directly proportional to the power of the device begins to flow.
  • The result is that, knowing the supply voltage and the power of the device, it will be much easier for us to calculate the electrical installation current by calculation. For this we use Ohm’s law.

Ohm's law

  • Of course, this law is valid only for the DC network, and for the AC network it is necessary to introduce another power factor. But for the simplest calculations, it is quite possible to use it.
  • But if you do not know the power of the device or you have doubts about its work, then you need to know and how to measure the amperage in the outlet with the devices. In order not to cut the power supply cable of the electrical installation and not to disconnect the socket from it, you can make a simple device.

Create a device for measuring the current in the outlet

To create such a device, we need a plug, two sockets and a piece of wire. The plug will connect to the outlet where we measure. Connect to it the wires that go to the outlet number one. To create such a device, we need a plug, two sockets and a piece of wire

Connection diagram of our device

Connecting the number one socket is slightly different from the usual. To one of the power clamps we connect the wire from the plug. And to the second power terminal we connect the wire going to the socket number two. Connecting the number one socket is slightly different from the usual

Connecting sockets in our circuit

To the socket number two, we connect one wire from the socket number one. We connect the second power contact to the plug wire that is not used in the connection to the first socket. To the socket number two, we connect one wire from the socket number one

Connecting multimeter test leads

Now in stages. We put the probes of our multimeter into the socket number one. We turn on the plug of our device into the socket. We connect to the plug number two our electrical device. Now in stages

Measurement of current in the outlet using a multimeter

If we did everything correctly, then now we can measure the current in the outlet with a multimeter. Moreover, when removing at least one of the probes from the socket number one, our electric device stops working. But we do not recommend breaking the chain by removing the probe. Do it better with a fork.

  • If you are looking for a simpler way to measure the current in the outlet or any other electrical installation with your own hands, then you will need electrical clamp. The peculiarity of this device is that you can measure the strength of the current without breaking the circuit. And you can do it at any time convenient for you at any stage of the electrical installation.

Electric Clamp Meter

  • The essence of this device is reduced to measuring the magnetic field around the conductor, through which it can determine the current flowing through the wire. For this, it has a disconnectable magnetic circuit. An open magnetic circuit allows you to close it around the conductor under study and make measurements.

Note! If you have a two-, three-, or other stranded wire, then you must measure for each wire of one phase separately. If you close the magnetic circuit around the wires of all phases, the device will show zero. This is due to the fact that the magnetic fields around each of the conductors will compensate each other and the resulting value will be zero or a very small value.


As you can see the multimeter is a fairly universal device that allows you to make a wide range of measurements. But he requires the right approach and knowledge of the principle of operation of electrical installations.

Therefore, if you want to install a power meter in the socket, or other, in most cases, excessive devices, we recommend first to recall the lessons of the foundations of electrical engineering. And then make decisions about the need for such devices and measurements.

How to work with a multimeter?
How to work with a multimeter?