What is zero and phase: how to determine phase and zero yourself. Indicator screwdriver: how to use? How to determine the phase and zero with an indicator screwdriver? Find zero in a three-phase network

In this article, we will consider the question of how to find the phase and zero using a probe and a multimeter.

If it is necessary to maintain apartment electricians, in particular, replacing sockets, light switches, or carrying out minor repairs, it becomes necessary to determine the phase and zero. If a person has some knowledge of the basics of electrical engineering, then it will not be difficult for him to find the phase and zero. But what if you don't have these skills? Searching for phase and zero is not as difficult a process as it might seem. Consider several ways to determine the phase and zero.

First, let's define what phase and zero are. Our entire energy system is three-phase, including low-voltage lines that feed houses and apartments. As a rule, the voltage between any two phases is 380 volts - this is line voltage. Everyone knows that the voltage of the household network is 220 volts. How to get this voltage?

For this, a neutral wire is provided in electrical installations with an operating voltage of 380 volts. If we take one of the phases and the neutral wire, then there will be a potential difference of 220 volts between them, that is, this is the phase voltage.

For a person who does not have knowledge in the field of electrical engineering, the above is not very clear. It is important for us to know that one phase and one zero comes to each apartment or house. In detail, what is phase and zero is considered.

So, you have two wires and you need to determine which one is phase and which is zero. First, it is necessary to de-energize them by turning off the circuit breaker that feeds this line of electrical wiring.

Then it is necessary to strip both wires, that is, remove 1-2 cm of insulation from it. The stripped conductors must be slightly separated so that when voltage is applied, a short circuit does not occur as a result of their contact.

The next step is to determine the phase wire. We turn on the machine, through which voltage is applied to the conductors. We take the indicator screwdriver by the handle and touch the metal part at the base of the handle with one finger.

Remember that it is strictly forbidden to take the probe below the handle, that is, by the working part. We bring the probe to one of the wires and touch it with the working part. In this case, the finger remains on the metal part of the handle.

If the lamp of the indicator screwdriver lights up, then this wire is phase, that is, phase. The other wire, respectively, is zero.

If the probe lamp does not light up when you touch the wire, then this is the neutral wire. Accordingly, the other wire is the phase, you can check this by touching the indicator screwdriver.

But what if the wiring in the apartment is made with three wires? In this case, you have not only phase and zero, but also. Using a probe, you can easily determine which of the three wires is the phase.

But how to determine where is zero, and where is the protective conductor, that is, the grounding conductor? In this case, one indicator screwdriver is not enough. Consider a method for determining zero in a three-wire household network.

You can determine where is zero, and where is the protective (grounding conductor), using a multimeter. So, we have already determined the phase wire using a probe. We take a multimeter and turn it on for a measurement range of alternating voltage of 220 volts and above.

We take two probes of the measuring device and touch one of them to the phase, and the other to one of the two remaining conductors. We fix the voltage value that the multimeter shows.

Then we leave one of the probes in phase, and with the other we touch the other wire and again fix the voltage value. When touched simultaneously to the phase and to zero, the value of the voltage of the household power supply, that is, approximately 220 volts, will be displayed. If you touch the phase and the protective conductor, then the voltage value will be slightly less than the previous one.

If you do not have a probe, then the phase can also be found with a multimeter. To do this, we select the measurement range of alternating voltage with a value above 220 volts. Two probes are connected to the multimeter in the "COM" and "V" sockets, respectively.

We pick up the probe that is included in the socket marked "V" and touch it to the conductors. If you touched the phase, the device will show a small value - 8-15 volts. When you touch the neutral wire, the readings of the device will remain at zero.

Very few people understand the essence of electricity. Such concepts as "electric current", "voltage", "phase" and "zero" are a dark forest for the majority, although we encounter them every day. Let's get a grain of useful knowledge and figure out what a phase and zero in electricity are. To teach electricity from scratch, we need to understand the fundamental concepts. We are primarily interested in electric current and electric charge.

Electric current and electric charge

Electric charge is a physical scalar quantity that determines the ability of bodies to be a source of electromagnetic fields. The carrier of the smallest or elementary electric charge is an electron. Its charge is approximately -1.6 times 10 to the minus nineteenth power of Coulomb.

Electron charge - the minimum electric charge (quantum, portion of charge) that occurs in nature in free long-lived particles.

Charges are conditionally divided into positive and negative. For example, if we rub an ebonite stick on wool, it will acquire a negative electrical charge (an excess of electrons that were captured by the atoms of the stick upon contact with the wool).

The same nature has static electricity on the hair, only in this case the charge is positive (the hair loses electrons).

The main type of alternating current is sinusoidal current . This is a current that first increases in one direction, reaching a maximum (amplitude) begins to decline, at some point becomes zero and increases again, but in the other direction.

Directly about the mysterious phase and zero

We all heard about the phase, three phases, zero and grounding.

The simplest case of an electrical circuit is single phase circuit . It has only three wires. On one of the wires, the current flows to the consumer (let it be an iron or a hair dryer), and on the other, it returns back. The third wire in a single-phase network is ground (or ground).

The ground wire does not carry a load, but serves as a kind of fuse. In case something gets out of hand, grounding helps prevent electric shock. Through this wire, excess electricity is diverted or "drains" into the ground.

The wire carrying current to the device is called phase , and the wire through which the current returns - zero.

So, why do we need zero in electricity? Yes, for the same as the phase! Through the phase wire, the current flows to the consumer, and through the zero wire, it is discharged in the opposite direction. The network through which the alternating current is distributed is three-phase. It consists of three phase wires and one reverse.

It is through such a network that the current goes to our apartments. Approaching directly to the consumer (apartments), the current is divided into phases, and each of the phases is given zero. The frequency of current direction change in the CIS countries is 50 Hz.

Different countries have different standards for voltages and frequencies in the network. For example, a typical household outlet in the United States is supplied with alternating current with a voltage of 100-127 volts and a frequency of 60 hertz.

The phase and zero wires must not be confused. Otherwise, you can arrange a short circuit in the circuit. To prevent this from happening and you do not confuse anything, the wires have acquired a different color.

What color are the phase and zero indicated in electricity? The zero is usually blue or cyan, while the phase is white, black, or brown. The ground wire also has its own color - yellow-green.

So, today we learned what the concepts of “phase” and “zero” mean in electricity. We will be just happy if this information was new and interesting for someone. Now, when you hear something about electricity, phase, zero and earth, you will already know what it is about. Finally, we remind you that if you suddenly need to calculate a three-phase AC circuit, you can safely contact student service. With the help of our specialists, even the wildest and most difficult task will be "too tough" for you.

The owner of an apartment or a private house, who decides to do any procedure related to electricity, whether it is installing a socket or switch, hanging a chandelier or a wall lamp, invariably faces the need to determine where the phase and neutral wires are located at the place of work, as well as the ground cable. This is necessary in order to correctly connect the element to be mounted, as well as to avoid accidental electric shock. If you have some experience with electricity, then this question will not confuse you, but for a beginner it can be a serious problem. In this article, we will understand what a phase and zero are in an electrician, and tell you how to find these cables in a circuit, distinguishing them from each other.

What is the difference between a phase conductor and a zero conductor?

The purpose of the phase cable is to supply electrical energy to the right place. If we talk about a three-phase electrical network, then in it there are three current-carrying wires per single neutral wire (neutral). This is due to the fact that the flow of electrons in this type of circuit has a phase shift of 120 degrees, and the presence of one neutral cable in it is quite enough. The potential difference on the phase wire is 220V, while the zero one, like the ground wire, is not energized. On a pair of phase conductors, the voltage value is 380 V.

Line cables are designed to connect the load phase with the generator. The purpose of the neutral wire (working zero) is to connect the zeros of the load and the generator. From the generator, the electron flow moves to the load along the linear conductors, and its reverse movement occurs along the zero cables.

The neutral wire, as mentioned above, is not energized. This conductor performs a protective function.

The purpose of the neutral wire is to create a circuit with a low resistance value, so that in the event of a short circuit, the amount of current is enough to immediately trip the emergency shutdown device.

Thus, damage to the installation will be followed by its rapid disconnection from the public network.

In modern wiring, the sheath of the neutral conductor is blue or cyan. In old circuits, the working neutral wire (neutral) is combined with the protective one. This cable has a yellow-green coating.

Depending on the purpose of the power transmission line, it may have:

Solidly earthed neutral cable.
Insulated neutral wire.
Effectively grounded zero.

The first type of lines is increasingly used in the arrangement of modern residential buildings.

In order for such a network to function correctly, the energy for it is generated by three-phase generators and is also delivered through three phase conductors under high voltage. The working zero, which is the fourth wire in a row, is supplied from the same generator set.

Clearly about the difference between phase and zero in the video:

What is a ground cable for?

Grounding is provided in all modern electrical household appliances. It helps to reduce the amount of current to a level that is safe for health, redirecting most of the electron flow to the ground and protecting the person who touched the device from electrical shock. Also, grounding devices are an integral part of lightning rods on buildings - through them, a powerful electric charge from the external environment goes into the ground without harming people and animals, without causing a fire.

The question - how to determine the ground wire - could be answered: by a yellow-green sheath, but color marking, unfortunately, is often not respected. It also happens that an electrician who does not have sufficient experience confuses a phase cable with a zero one, or even connects two phases at once.

To avoid such troubles, you need to be able to distinguish conductors not only by the color of the sheath, but also in other ways that guarantee the correct result.

Home wiring: find zero and phase

You can install at home where which wire is located in different ways. We will analyze only the most common and accessible to almost anyone: using an ordinary light bulb, an indicator screwdriver and a tester (multimeter).

About the color marking of phase, neutral and ground wires on the video:

Checking with a light bulb

Before proceeding with such a test, you need to assemble a test device using a light bulb. To do this, it should be screwed into a cartridge of a suitable diameter, and then fixed to the wire terminal, removing the insulation from their ends with a stripper or an ordinary knife. Then the lamp conductors must be alternately applied to the test cores. When the lamp lights up, this will mean that you have found a phase wire. If a cable is checked for two cores, it is already clear that the second one will be zero.

Checking with an indicator screwdriver

A good helper in work related to electrical installation is an indicator screwdriver. The operation of this inexpensive instrument is based on the principle of capacitive current flowing through the body of the indicator. It consists of the following main elements:

A metal tip shaped like a flathead screwdriver that is applied to the wires for testing.
A neon lamp that lights up when current passes through it and thus signals the phase potential.
Resistor for limiting the amount of electric current, which protects the device from burning under the influence of a powerful flow of electrons.
A contact pad that allows you to create a circuit when touched.

Professional electricians use more expensive LED indicators with two built-in batteries in their work, but a simple Chinese-made device is quite affordable for anyone and should be in every home owner.

If you check the presence of voltage on the wire using this device in daylight, you will have to look more closely during work, since the glow of the signal lamp will be poorly noticeable.

When the tip of the screwdriver touches the phase contact, the signaling device lights up. At the same time, it should not glow either at the protective zero or at the ground, otherwise it can be concluded that there are problems in the connection diagram.

When using this indicator, be careful not to inadvertently touch live wires with your hand.

About the definition of the phase clearly in the video:

Checking with a multimeter

To determine the phase using a home tester, the device must be put into voltmeter mode and the voltage between the contacts should be measured in pairs. Between the phase and any other wire, this indicator should be 220 V, and applying the probes to ground and protective zero should indicate the absence of voltage.

Conclusion

In this material, we answered in detail the question of what a phase and zero are in a modern electrician, what they are for, and also figured out how to determine where the phase conductor is located in the wiring. Which of these methods is preferable is up to you, but remember that the issue of determining phase, zero and ground is very important. Incorrect test results can cause devices to burn out when connected, or worse, cause electric shock.

Carrying out repair work in any room, an important point is to equip this room with electricity. In addition to electrical wiring, do not forget about the need to install sockets and switches, with which the lighting will be regulated. Here, a rather important point will be the determination of the phase, zero and grounding conductor of the system.

For professional installers, this task is very simple, which cannot be said about ordinary people who are far from always able to cope with such a task. However, the search for zero and phase is not as complicated as it might seem initially, and it includes several ways to determine.

It should be understood that the wiring in the apartment usually has a voltage of 220V, since it provides for connection to the neutral conductor and to one of the phases. At the same time, grounding is mandatory, which makes the electrification of the room safe for the inhabitants.

What is phase and zero in electricity for a beginner

To catch the principle of finding the phase and zero in the network, you should first determine for yourself what these terms mean, which for a simple layman may sound like completely incomprehensible concepts. Any system, regardless of its length, consists of three phases, and it also applies to low-voltage lines, the task of which is to power residential buildings.

Between any two phases there is a linear voltage of 380V. However, the voltage of the household network is 220V, the main task is the appearance of the voltage required for the network. For this purpose, in any network there is a neutral wire, which, in combination with any phase, forms a potential difference of 200V, which will be the phase voltage.

Zero in an electrical circuit is a conductor that is connected to the ground loop and is used to create a phase load. This phase is connected to the opposite end of the winding on the transformer substation. Thus, in a standard outlet, for clarity, one input is taken as phase, and the second as zero.

In simpler terms, a phase is a wire through which current flows. The neutral wire returns the current back to the source. Depending on the number of phases, the system has several wires. Let's say in a three-phase circuit there are three phase wires and one return, zero.

Color designation. Not infrequently, many are interested in the question of what color the wires are, phase zero ground, how to determine where which wire is, often made possible with the help of color distinctions used in electrics. However, this method will work only if the posting is really done according to all the rules. The insulation of the neutral wire is usually indicated in blue or blue, the earth combines two colors at once - green and yellow. The phase wire according to the rules is designated in brown, white or black.

Designation of phase and zero letters. In addition to color coding, letter marking of wires is also possible. The phase is usually denoted by the Latin letter “L” and the neutral wire is usually marked with the letter “N”. In addition, grounding has its own designation, which is usually denoted by the letter “G”.

How to determine the phase and zero with an indicator screwdriver

Various tools can be used to find the phase and zero in the network. The most successful invention to help novice electricians is an indicator screwdriver, which has special sensitive elements and a reflective indicator.

It is easy to check the phase and zero in the network with a screwdriver. The screwdriver should be clamped between the thumb and middle finger. It is not allowed to touch the non-insulated part of the screwdriver tip. The index finger should be placed on the metal round protrusion at the end of the handle.

It is not difficult to determine the principle of operation of an indicator screwdriver; inside it is a special lamp, as well as a resistor, which is a resistance. The lamp lights up if the circuit closes. Thanks to the resistance, you can not be afraid of electric shock during the test, since it reduces its value to a minimum.

How to find out where the phase is and where the zero is in the socket with an indicator probe video

Finding zero with such a screwdriver, respectively, will not work. In addition, this method often fails due to not very good sensitivity. As a result, an indicator screwdriver, reacting to pickups, can give out voltage where it is completely absent.

Determination of phase and zero with a multimeter

In addition to using an indicator screwdriver, it is possible to use a multimeter, which will also allow you to determine the current-carrying wires in the network. A prerequisite for its use is the preliminary stripping of wires.

On the device, before use, it is required to set the value of the measurement limit for alternating current, the value of which must exceed 220V. You should also be guided by the marking of the sockets where the probes of the device are included. This type of test will require a probe plugged into the socket marked "V".

The test itself consists in touching the probe to one of the wires, while monitoring the readings of the device. If the multimeter identifies any voltage, then this wire is phase. If the other wire shows a zero value, then this, respectively, is the neutral wire.

The device for work can be used of any type - pointer or with a digital indicator. In any case, the important point will be the observance of safety measures, as well as the correct indication by the device of readings from the wires. The accuracy of this device is usually higher than the indicator screwdriver.

The main rule when using a multimeter is the prohibition of simultaneous contact with the phase wire and the ground loop. Such negligence can lead to a short circuit and, as a result, to traumatic burns.

How to find phase and zero without instruments

Despite such a wide distribution of instrumental methods for determining the phase and zero in the network, it is not always possible to have the right device at hand that will allow you to make the right conclusion. At the same time, incorrect detection of wires in the network “by eye” can lead to quite dangerous consequences.

The first method to cope with this task was described in one of the sections above. It consists in finding the wires, depending on the color of their insulation, as well as on the marking. However, this will only be true if the posting was done in accordance with all the rules.

The second way to identify them is to make a so-called control light, while using improvised means. This will require a simple incandescent lamp and two pieces of wire, about 50 centimeters long. The cores of the wires should be connected to the light bulb, while the second end of one of the wires should touch the heating pipes (stripped), and the second end should touch the “ringing” wires. The wire, when touched, which lights up the light, is phase.

Phase detection without indicator and video device

It is worth noting that the described method is very dangerous and can lead to electric shock during its use. In no case is it recommended to use it in case of limiting voltage in the network, and you should also not touch bare wires.

An alternative to an incandescent bulb can be a neon bulb, which will allow you to find the polarity of the system.

In conclusion, it should be noted that the answer to the question "how to determine the phase and zero" has several solutions. Namely: an indicator screwdriver, a multimeter, and it is also possible without devices. It all depends on the capabilities and availability of tools at hand. It is mandatory to comply with all safety measures when working with electricity.

When repairing electrical wiring, or maintaining it, it may often be necessary to determine which wire is connected to zero and which to phase. This is required for installing switches or switching other electrical equipment. Before telling how to determine zero and phase, let's talk about the prejudices associated with this.

The most common misconceptions

Here are the most common misconceptions associated with the definition of the neutral and phase wires:

An example of such equipment is a controller that controls the operation of a gas boiler. When the error "not enough voltage" is indicated, the polarity must be reversed.

A similar problem can occur on the pulse generator, as well as when connecting laboratory measuring equipment;

if there are three cores in the cable, and one of them is multi-colored, then it is grounding. One can never be sure of this, especially given the confusion with GOSTs in the last decade of the last century. Therefore, it is better to always check the cable.

Color coding

In order not to bother yourself with the search for zero and phase in the future, it is necessary to adhere to a single standard prescribed in GOST R 50462-92.

The table shows what color this or that wire is indicated.

In older houses, wiring can be done with a single color wire. If you have a similar situation, we recommend marking the wiring leads with heat shrink tubing.

It is not necessary to trust the color coding if you have the slightest doubt. It is better to once again make sure that the purpose of the wires matches the colors.

The most accessible and common ways

The simplest way, which allows you to accurately determine the phase and neutral wires, is performed with an indicator screwdriver. You can buy it or build it yourself. The scheme of such a device is simple, it is shown in the figure below.

Designations on the diagram:

A - contact plate;
B - detector tip;
R1 - resistance with a nominal value of 1.5 to 2 MΩ, power from 0.5 W;
HG1 - any type of neon lamp.

Video instruction: determining the phase and zero with an indicator screwdriver

The compact dimensions of the parts used make it possible to assemble the device in the body of a ballpoint pen. Industrial designs resemble a small screwdriver in appearance.

Determining the connection of a wire to a phase or phase zero (in a two-wire electrical circuit) produced according to the step-by-step algorithm described below:

the wiring is de-energized;
the protective layer of insulation is removed from the wires to be tested (one centimeter will be enough);
we turn on the electricity, since it will not work to determine zero if the phase is off;
two wires are checked in turn with the tip of the probe, while touching the contact plate of the indicator, as shown in the photo;
if the neon lamp lights up, the tested core is a phase of the electrical circuit.

In the socket, the voltage indicator works on two contacts

The situation when the probe detects two phases in the outlet and does not see zero can puzzle a novice electrician. The matter will be even more confused if you measure the potential difference with a multimeter or tester. They will show that there is no voltage. These are characteristic signs of a zero break.

Note that with external signs of a lack of voltage in the wiring (according to the readings of the multimeter), you can get a rather noticeable electric shock. That is why you can not neglect the voltage probe.

To solve this problem, it is enough to eliminate a break in the neutral wire, if you do not know how to do this, it is better to entrust this work to professional electricians.

Methods for three-core wiring

In this case, the third wire will be ground. The phase is easily found with a probe (how to do this was described above). To find zero and ground, you should use a multimeter or tester to determine them.

The procedure should be as follows:

using a probe, we determine the phase;
measure the voltage between the phase and the remaining two wires;
the potential difference between zero and phase will be around 220V, the voltage between ground and phase will be less than this value.

Actually, having a multimeter, you can determine the ground, zero and phase without a voltage indicator. We will tell you how to do this using the M820D model.

For this purpose, it is necessary to set the measurement range of alternating current to more than 220V. The probes are connected to the V and COM jacks (shown in the photo below).

We alternately measure the voltage between the three wires, where it will be about 220V, one core is a phase, the second is zero. Accordingly, the third wire is ground.

Video: determining the phase and zero with an indicator screwdriver and a multimeter (2 ways)

No required appliances

The household should have at least a voltage probe, but if you don’t have one, don’t be discouraged, there are ways to determine the ground, zero and phase without devices.

All that is required of you is to make a control lamp, approximately the same as shown in the photo. The lamp should work from 220V and not be too powerful (so as not to blind your eyes).

There are many options for implementing this device, the main thing is to ensure reliable insulation at the points of attachment of wires to the lamp and probes. Naturally, if you need to test the wires in the box on the ceiling, you need to make probes of the appropriate length.

To determine the phase, it is enough to connect one contact of such a probe to the wire under test, and the second to ground. As the latter, metal pipes for heating or cold water can act. The place on the pipe that you will touch with the test lamp probe must first be cleaned.

The wire, when touched, the lamp will glow, and will be the phase.

A lot of videos have been published on the Internet on how to determine the phase without using any special equipment. For example, using raw potatoes or tap water. We want to warn that the repetition of such dubious experiments can cause significant damage to your health.

We have told how to determine zero and phase, and do it with maximum safety, so there is no need to invent new methods.