How to check the voltage in an outlet with a multimeter: measurement rules

Safety during installation and repair of electrical installation devices must be ensured by all possible means.It is necessary to exclude both light shocks and severe electric shocks. Do you agree? Before performing any actions with electrical points, it is necessary to check the voltage, which is done using a multimeter.

We will tell you what this portable device is and how it works, used by both home craftsmen and professional electricians. Here you will learn how to check the voltage in an outlet with a multimeter, as well as whether there is voltage in the network itself. Let's look at how it can be used to measure current strength.

For you, we have described in detail the types of multimeters and given the rules for their use. To optimize the perception of a difficult topic, we included photo collections, diagrams, and videos.

Multimeters, testers and their varieties

Multimeter, also known as a multitester, is a special device for measuring a wide variety of characteristics and parameters of the electrical network, as well as the parts and elements powered by it.

The device is designed so that at a construction or repair site it is possible to determine with high accuracy:

• constant and alternating voltage;
• alternating and direct current;
• resistance, capacitance and much more.

In addition to the above parameters, multimeters are equipped with additional measurement functions, which also allows you to test transistors and “ring” electrical wiring cable to the junction box and the wires coming out of it, check the functionality of the diodes, etc.

There are two main types of metric instruments: analog and digital. These devices differ in functionality, measurement accuracy, build quality, and packaging. In any case, these are very useful measuring systems for everyone.

In an analog multitester, the measurement result is displayed using a regular arrow on the scale. Sometimes the operation of such an analog device is not entirely appropriate - it is difficult for a beginner or non-expert in the field of electrical engineering to understand all the scales, the “division value” of a certain parameter, and calculate the final value of the electrical characteristic.

And yet, the analog tester does not have a fixed pointer in position, which makes it difficult to read the result and generally work with the device.

A digital multimeter displays measurement results as digital values ​​on an LCD screen. It ensures extreme ease of operation of the device, eliminates any errors associated with taking readings and calculating the required parameter, taking into account the “division value” of the scale. This is one of the main reasons for the popularity of digital multitesters among craftsmen.

Standard multimeters can cost more than $5. But one thing always remains the same - the rotary trigger occupies the central place on the panel. The location of the remaining controls in the corners of the panel, the presence of the necessary connectors at the bottom of the panel, and multi-colored symbols do not change.

If you purchase such a product, be sure to buy it with an external silicone cover, which protects against dust, moisture, falls from a small height, has special clamps and a stand, which can be very useful in the most unexpected situations of using the multitester.

Household power supply

Considering the topic and specifics of the article, we are talking about the metric measurement of a household power supply network. But to carry out work to determine the parameter values, it is necessary to have at least an approximate idea of ​​the characteristics household electrical power networks.

And the socket, in this case, acts exclusively as an “output point” for voltage, so it is reasonable that you need to know what voltage in the socket the consumer will “work” with.

All over the world, there are several main categories of electrical power networks for household electrical appliances, one of which is “our” 220 V with a frequency of 50 Hz. It consists of two wires (“phase” and “zero”), the voltage between which is 220 V.

Recently, for supply systems for private houses and apartments, a 3-phase voltage network of 380 V with a frequency of 50 Hz is sometimes connected to “power” devices such as a pumping station, compressor, lathe, etc.

The household electrical network “provides” 220 V (single phase) voltage in sockets for current foreign and domestic household appliances: from kettles and hair dryers to dishwashers and washing machines

A natural question arises: why is it necessary to measure network characteristics? On the one hand, the answer is obvious: if you do not know or are not confident in your beliefs regarding the outlet that you see in front of you and you need to do some work with the wiring.

On the other hand, most electrical appliances are precisely designed for a specific frequency and voltage. Some electrical devices are designed to operate from a 60 Hz power supply.

For example, an imported microwave oven made in South Korea is equipped with a transformer, which can easily “swell” from “our” 50 Hz and it (the oven) will quickly fail.

Exceeding or decreasing frequency, voltage and current can significantly change the efficiency of devices, as a result of which the electrical device fails and subsequent operation is impossible. Multimeters are needed to measure and monitor such network parameters.

Safety precautions before work

A multitester is a multifunctional portable device that is powered by a battery (usually a crown) and is a convenient, and most importantly safe, tool for the end user. But for its operation there are certain rules of use.

“Krona” is a battery of galvanic batteries, overall dimensions 48.5X26.5X17.5 mm. The battery weight is about 53-55 grams. Output voltage - 9 V, average capacity - 600 mAh

The tester itself is equipped with internal protection against overloads and overvoltages. But without following the rules below, it can also easily “burn out” and partially fail. To avoid this, there are a number of general rules for the safe operation of a digital tester.

When measuring AC input voltage:

1. If the preliminary value of the measured voltage has not been determined, set the switch to the largest range.
2. Do not apply voltage more than 750 V to the input to avoid damaging the internal circuit.

Hands without dielectric gloves should not touch electrical components.

When measuring DC and AC input current:

1. If the preliminary value of the measured current has not been determined, set the switch to the largest range.
2. If the LCD display is set to “1”, set the trigger to the next range in the direction of increasing the maximum value.
3. When working with the “20A” connector, the testing time should not exceed 15 seconds, since there is no fuse for this mode.

When measuring the internal resistance of a circuit, you need to make sure that the power to the circuit is turned off and all capacitors are discharged to zero.

The fuse is a glass bulb with external metal contacts in the form of “caps”. Inside the flask there is a piece of wire that melts at the moment of overload; it opens the circuit and prevents the device from breaking.

In addition, there are special rules for the care and storage of the device, namely, you do not need to apply voltage to the input if the rotary switch is in the Ohm position, and work with the device if the housing cover is not completely closed. And lastly, replacing the galvanic battery and fuse is carried out only with the device turned off and the probes disconnected.

Multimeter symbols

In fact, the multitester consists of several standard parts: a display (in analog – a scale with protective glass), a multi-position rotary switch, connectors for connecting probes. In this article, the DT9205A model is considered as a multimetric device.

The digital multitester DT9205A has extensive capabilities, including measuring AC and DC voltage and current, resistance, capacitance, and diode health. Size - 186x86x41 mm, weight - 318 grams

Buttons:

• ON/OFF—turn on/off the device;
• HOLD - Holds the displayed value on the LCD screen.

Central switch sectors:

• hFE – measurement of transistor parameters;
• F, Ω - testing capacitor capacity and resistance;
• A-, A~ - direct and alternating current;
• V-, V~ - constant and alternating voltage.

Main connectors:

• 20A - socket for measuring current up to 20A, red probe;
• A - socket for testing current strength within ranges;
• COM - socket for all modes, usually a black probe is connected;
• VΩ - socket for measuring resistance and voltage.

Section connectors “pnp/npn” - semiconductor testing, “cx” - connectors for inserting the capacitor being tested. It is imperative to observe the polarity, otherwise it will “swell.”

In order to use a multitester correctly, you should know what functions it has. Buttons indicating functions are located on the front panel (+)

Connecting probes to a multimeter

Probes are a special type of connectors that help measure the characteristics of electrical parts and sections of a wire circuit. They easily connect the necessary connectors of the multitester with other outputs.

Usually they are a metal rod with plastic insulation, at one end of which the rod exits from the other - a wire with a connector for insertion into the 20A, A, COM and VΩ connectors of the device.

In addition, sometimes it is necessary to have an additional set of probes in your arsenal, but instead of a rod, metal “crocodiles” are used - toothed clamps.

“Crocodile” is a special type of attachment for multitester probes, very convenient for measuring the electrical characteristics of medium and large parts

Most devices are imported from China, where they are manufactured in factories, workshops and mini-workshops. In this regard, manufacturers save on everything, including materials for probes, which quickly fail.

It is recommended to make the probes yourself by purchasing parts on the radio market or in a radio store. Instead of insulating plastic, empty ampoules and casings for ballpoint pens are often used.

The COM connector is an electrical “minus” and performs the grounding function in all modes and ranges. Usually a black probe is connected here

We connect the plug of the black probe into the multimeter connector marked COM. And we connect the plug of the red probe into the connector marked VΩ, which is designed for measuring direct and alternating voltage.

We strongly do not recommend pressing the red and black probes onto the contact in any mode, with the exception of the rotary switch in the “►” position (chain continuity).

In addition to voltage, the multitester can measure current and resistance values. It is important to remember that when measuring resistance values, you must turn off the power

Measuring AC voltage in a socket

Introductory and preparatory work has been completed.Let's move on to the actual execution of the task. First of all, turn off the multitester if it is turned on. Press the ON/OFF button.

We move the rotary trigger of the multimeter to the “750” position (in other testers it can be 600, 1000) of the “V~” section. This means that the device can measure AC voltage parameters ranging from 0 to 750 V.

If we set the range below the rated desired voltage (less than 200 V), we can damage the device, thus creating an overvoltage situation. In the best case, you will have to change the fuse, in the worst case, you will have to “use” the multitester for spare parts

We turn on the tester, at least one “zero” should appear on the liquid crystal screen - the device is ready for use. We insert the probes into the holes of the socket one by one, it doesn’t matter which one goes where. We take readings of the alternating current of the household power supply network.

The values ​​on the screen jump and do not show exactly 220V - this is normal, because we are dealing with a single-phase network with alternating voltage

Work on testing the power supply network must be carried out quite carefully, slowly and without touching the exposed parts of the probes.

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.

Current strength in regular 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. Household power supply has simply 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.

Measuring battery voltage and current

Instead of measuring current in an outlet, it is better to learn how to measure direct current and voltage in batteries, accumulators and power supplies. It's much more interesting and safer. In addition, everyone has enough of these electrical elements. They are usually found in things like cameras, phones, tablets, children's toys, etc.

Batteries and accumulators are easy to distinguish: they all have special inscriptions near the output contacts in the form of “+” and “-“ signs. Testing such elements is no more difficult than testing the voltage or current in an outlet.

It should be noted that these batteries are usually characterized by low voltage and current values. To measure direct voltage or current on a battery, it is necessary to switch the rotary trigger of the multitester to the corresponding mode of the “V-” or “A-” sections, which is greater in value than indicated on the outer shell of the element.

Turn on the tester. We connect the black probe (zero) with “-”, and combine the red probe with “+”.We remove the fixed constant value. In this way, you can measure the basic electrical parameters of batteries, which will help determine their operating condition.

Conclusions and useful video on the topic

The video will clearly demonstrate the sequence of actions when taking measurements in dynamics:

The article clearly explains how to measure voltage and current in an outlet for everyone who knows and is just getting acquainted with electrical points and electrical wiring. Using a multimeter will significantly reduce the likelihood of dangerous situations occurring when installing and repairing wiring, replacing sockets and switches.

Do you have some interesting information to share about using a multimeter? Did you have any questions while reading the article? Please write comments in the block intended for feedback.