How to find phase and zero with a neon lamp. How to find zero and phase with an indicator screwdriver, multimeter and without instruments? The design of the indicator screwdriver

Installation of internal wiring, self-installation of switches and sockets is often associated with the need to determine the phase and neutral wires. This process is not difficult if you have an idea about the possible ways and rules for working safely with electricity. We have devoted today's article to the solution of these questions.

First, let's remember a little theory. Everyone knows that for the operation of household electrical appliances, very little is needed - the presence of a voltage of 220 volts in the mains. To supply electricity directly to two (in modern homes - three) wires are used. The first of them is phase, the second is zero and the third is grounding, which protects the user from electric shock in the event of a malfunction in the insulation of the device. Why does an ordinary resident of a high-rise building or a country house need to be able to determine zero and phase?

This knowledge may be needed, for example, when replacing a switch on your own, which is recommended to be installed on a phase wire. This makes it possible to carry out repairs to the lighting fixture without turning off the electricity in the entire apartment. In addition, installation of an outlet for connecting various household appliances, especially those whose work is associated with the use of running water, as well as those with metal cases. To connect them, in addition to the traditional phase and zero, it is also necessary to use a third wire - grounding.

Phase search by indicator

These days, there are several ways to determine the phase without the involvement of a professional electrician. The first of them involves the use of the so-called probe, or phase indicator. It is a narrow flat screwdriver with a plastic handle, which contains a light signaling device - a semiconductor or neon light bulb.

The technology for determining the phase with this device is simple. It is enough just to touch the tip of a screwdriver to the bare wire under study or immerse it in one of the plug holes of the socket.

If there is voltage on the wire or in the socket, the phase screwdriver signaling device will respond with a slight glow. But this will happen only with the correct use of the device - one of the fingers of the hand in which you hold the device must be pressed against the metal end of the handle. In this case, you close the circuit between the wire and the ground, but you should not be afraid of this, since the voltage drops sharply with a screwdriver and will not bring any harm to the user.

Phase detection by tester

The second option for determining the phase wire involves the use of a more advanced device - a tester or multimeter. It allows you to measure various electrical quantities of direct or alternating current. Using the rotary switch, set the device to measure the potential difference of the alternating current. Hold one of the probes of the device firmly in your hand, and with the second touch the wire under test or deepen it into the hole in the socket. In the event of a hit on the neutral wire, the multimeter display will show a set of zeros or a small voltage, usually not exceeding two volts. When in contact with the phase conductor, the numbers on the instrument display will be higher.

There is a third option, which can be attributed to the most unreliable. The fact is that at present, according to the rules for installing intra-house and industrial electrical networks, all wires have a certain color marking, depending on their purpose. So, a black or brown conductor should be used to connect to the phase, blue or blue to zero, and the grounding conductor should be painted partly yellow and partly green.

Unfortunately, the peculiarities of our country and many irresponsible electricians often lead to ignoring the established rules, which can lead to unpleasant consequences. You should not completely rely on the professionalism and skill of the workers involved in the installation of electrical networks in your home. It is better to use the above methods. In addition, until 2011, the wire marking was different from the current one. So, a wire painted black was used for grounding.

Having determined the phase wire, and gently bending it, we proceed to the definition of the neutral wire and the ground wire. The peculiarity of connecting them to the in-house shield does not imply the input of a grounding conductor directly into the housing of the input device. In the event that you have access to the shield, you can specify the color of the conductor passing by the machines installed in it and determine its color.

In the event that access to the shield is not possible or, if you wish, to play it safe, you can use the simplest device that any electrician always has - a light bulb with a cartridge and wires attached to it. By connecting or simply touching one of the wires extending from the bulb to the phase wire, short the second wire in turn to the two remaining wires intended for determination. Upon contact with zero, the light should light up. Contact with a ground wire usually has no such effect.

As opposed to the simplest device, you can use the multimeter already described. Alternately measure the potential difference (voltage) between the known phase and the rest of the wires. The value of the zero-phase pair should significantly exceed the value of the phase-to-ground pair.

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Let's try to figure it out how at home, without having complex specialized measuring tools and electronic devices, to determine for yourself where the phase is, where is zero, and where is the ground in the wiring.

Of all the known methods, the simplest determination of the phase and zero, we have selected the most, in our opinion, available in implementation and at the same time safe. For this reason, in the article you will not see tips on how to find the phase with the help of potatoes or calls for briefly touching the wires with various parts of the body.

In fact, there are not so many options for determining the phase, zero or ground, for example, in a socket, without the use of specialized equipment, and sometimes, depending on your goals and objectives, it is enough just to know the color marking standard for electrical wires adopted by us to distinguish them.

Really, the easiest way to determine the phase, zero and ground of an electrical wire is to look at the color coding and compare with the accepted standard. Each core in modern wires used in electrical wiring, as well as electrical equipment, has an individual color. Knowing which color of the cores corresponds to which function (phase, zero or ground), you can easily perform further installation.

Quite often, this is quite enough, especially in cases where the installation is carried out in new buildings or places with fairly new electrical wiring, made by professional, competent electricians according to all modern rules and standards.

In our country, as in Europe as a whole, there is IEC 60446 2004, which strictly regulates the color marking of electrical wires.

According to this standard for an apartment electrical network:

Working zero (neutral or zero) - Blue wire or blue-white

Protective Zero (earth or ground) - yellow-green wire

Phase - All other colors including black, white, brown, red, etc.

Now, knowing the wire color code standard, you can easily determine which wire performs which function. This applies to most cases, with the exception of wires suitable for switches, switches, etc., due to a fundamentally different scheme of operation of this electrical equipment.

If you are not sure about the exact correspondence of the colors of the wire cores to the IEC 60446 2004 standard, you have old wiring, you do not exclude the possibility of errors or even negligent attitude of electricians to their work, or maybe electricians laid wires of a different standard and, accordingly, a different color marking, then we proceed to a practical method for determining the phase and zero (working and protective).

HOW TO DEFINE THE PHASE, ZERO and GROUND AT THE WIRES YOURSELF

So let's start in order:

PHASE DETECTION

For greater convenience, it is always better to determine which of the available wires is the phase first. We already wrote about how to find the phase with a digital multimeter, but what if it is not there, read below.

PHASE DETERMINATION WITH INDICATOR SCREWDRIVER

The easiest way to locate a phase wire- this is a search with an indicator screwdriver. This simple tool is a must have for any home electrician in an apartment - whether it's a complete electrical installation, a simple replacement of lamps, or the installation of fixtures, sockets and switches.

The principle of operation of the indicator screwdriver simple - when the tip of the screwdriver touches the live conductor and at the same time touches the contact, on the back of the screwdriver, with the finger of the hand, the indicator lamp in the tool body lights up, which indicates the presence of voltage. Thus, you can easily find out which wire is phase.

The principle of operation of the indicator screwdriver simple - inside the indicator screwdriver there is a lamp and resistance (resistor), when the circuit is closed (we touch the rear contact), the lamp lights up. Resistance protects us from electric shock, it reduces the current to a minimum, safe level.

This option for determining the phase on your own is the most preferable and we recommend using it, especially since the cost of an indicator screwdriver is more than affordable. The main disadvantage of this method is the probability of erroneous operation, when the indicator screwdriver, reacting to interference, determines the presence of voltage where it is not.

DETERMINATION OF PHASE, ZERO AND GROUND BY PILOT LAMP

Another way that you can determine the phase, neutral and ground wires in a modern three-wire electrical network is to use a test lamp. The method is ambiguous, but effective, requiring special care.

To begin the determination, it is first necessary to assemble the test lamp device itself. The easiest way is to use a cartridge with a lamp screwed into it, and fix the wires with the insulation removed at the ends in the terminals of the cartridge. If there is no electric cartridge at hand or there is no time to make something, you can use an ordinary table lamp with an electric plug.

The technology for determining the phase, zeros and grounds using a test lamp is as simple as possible - by connecting the wires of the lamp in turn to the wires that need to be determined, each with each.

Determine phase and zero from two wires

If a control lamp detects a phase wire among two wires, you can only find out whether there is a phase or not, and which of the phase conductors cannot be determined. If, when connecting the wires of the control lamp to the conductors being determined, it lights up, then one of the wires is phase, and the second is most likely zero. If it does not light up, then most likely there is no phase among them, or there is no zero, which also cannot be ruled out.

In this way, rather, it is more convenient to check the operability of the wiring and the correctness of its installation. It is better to determine the phase with an indicator screwdriver, but to recognize the presence of zero in this way.

In this case, you can determine the phase wire by connecting one of the ends coming from the control lamp to a known zero (for example, to the corresponding terminal in the electrical panel), then when the second end touches the phase conductor, the lamp will light up. The remaining wire, respectively, is zero.

Find phase, zero and ground from three wires:

In such a three-wire system, it is often possible to accurately determine the phase, neutral and ground wires with a test lamp.
We connect the contacts coming from the control lamp in turn to the cores of the cable that needs to be determined.

We act by elimination method:

We find the position in which the lamp is on, this will mean that one of the wires is phase and the other is zero.

Then we change the position of one of the contacts of the control lamp, then several options are possible:

- If the lamp does not light up(if there is either a differential circuit breaker of the line being tested, they can also work) which means that the remaining free wire is PHASE, and the tested ZERO and EARTH.

- If the lamp flashes briefly after changing the position, while immediately work or dif. the machine (if any), then the remaining free wire is ZERO, and the tested ones are PHASE and GROUND.

- If the line is not protected or by a differential machine, and the light will be on in two positions. In this case, you can find out which wire is working zero (zero), and which is protective (grounding), by simply disconnecting the input cable from the ground terminal in the power metering and distribution panel. After that, also check all the wires with a test lamp and, again by the elimination method, in the position when the lamp is off, identify the ground conductor.

As you can see, in different situations, with different wiring diagrams implemented in the apartment, the methods and methods for determining zero, phase and ground change. If you encounter a situation that is not described in this article, be sure to write in the comments to the article, we will try to help you.

BUT if you know more, simple ways of how to determine the phase, zero and ground at home, without a specialized tool, write in the comments. The article will be updated for sure. The main requirement for the methods of determination is simplicity, the ability to get by in the search with only improvised, household tools available to many.

As you know, the electricity that is supplied to our house is three-phase. The voltage between any two outputs is 380 V. At the same time, we know that the voltage used in household appliances is 220 V. How is one converted to the other?

The neutral wire plays an important role here. If you measure the voltage between one of the phases and this wire, then it will just be equal to 220 V. In more modern sockets, an additional zero output is provided - this is the so-called protective zero.

A natural question arises as to what is the difference between the two mentioned zeros? The first of them, “working zero” (we are trying to determine it) is a neutral contact on a three-phase installation of a generating substation, connected to a neutral contact of a three-phase installation in a house or a separate entrance.

He may not be grounded at all. The main purpose is to create a closed electrical circuit when powering household appliances. In the second case, we are talking about. It is commonly referred to as "protective earth".

Due to the rather complex nature of alternating current, there are some typical views on the neutral wire and on the ground, which may not correspond to the real state of affairs:

1. “There is no voltage at zero at all.” This is not true. It is connected to the zero connector at the substation and is designed to create a potential difference at the output. Sometimes he is under pressure.
2. “If there is grounding, then there will definitely not be a short circuit.” In most cases, it is. But if the current rises too quickly, it may not have time to leave through the ground in time.
3. “If two cores in the cable are the same, and the third is different, then this is probably the ground.” It should be, but sometimes it isn't.

Methods for determining

Digital multimeter

Determination of zero and phase by using a multimeter. This device is very useful for working with electricity. It includes various features. It can be both an ammeter and a voltmeter or an ohmmeter.

Also, depending on the specific type, there may be other possibilities (for example, frequency measurement). These devices can be either analog or digital.

Using an indicator screwdriver. This screwdriver has a transparent handle. If you insert it into the outlet in a certain way, then when it hits the phase, the light will turn on.

There are several designs of such screwdrivers. In the simplest case, when testing, you need to touch the end of the pen. Without this, the flame will not light up.

With visual testing, the purpose of the wires can be determined by their colors.

Using a special phase. This is a small digital device that fits in the palm of your hand. One of the wires must be held in hand, the other is checked for phase.

Step by step instructions

Let's talk in more detail about how to produce such work.

When using a multimeter, you need to correctly set its operating range. It should be 220 V for AC voltage.

It can be used to solve two problems:

1. Determine where the phase is, and where is the "working zero" or grounding.
2. Determine where, in fact, grounding, and where is the zero output.

Let's talk about how to complete the first task first. Before starting, you need to correctly set the operating range of the device. Let's make it more than 220 V. Two probes are connected to the "COM" and "V" sockets.

We take the second of them and touch the outlet hole to be tested. If there is a phase, then a small voltage will be displayed on the multimeter. If the phase is not there, then zero voltage will be shown.

In the second case, the operating voltage should be 220V. We insert one wire where there is a phase. We test others with others. When it hits the ground, exactly 220 V will be shown, otherwise, the voltage will be slightly less.

Using a phase tester

We hold one wire neatly with our fingers, we use the other for testing. If we hit the phase in the outlet, then the numbers on the indicator will be much greater than zero. When hitting zero, the screen will also show zero or a small amount of voltage.

This device is convenient both because it is generally available on the radio measuring equipment market, and because the measurements are made with a sufficiently high accuracy.

Using an indicator screwdriver

It looks like an ordinary screwdriver, but with a slight difference. It has a transparent handle with a small light bulb inside. This, at first glance, a rather primitive device, is actually very convenient.

It is enough to simply insert it into the outlet hole, while touching the opposite end of the screwdriver with your finger. If there is a phase, then the light will light up. If there is a neutral wire or ground, then it will not burn. It is important to remember that it is strictly forbidden to touch the metal part of the screwdriver during the measurement process. This may result in electric shock.

In some cases, the phase and neutral wire can be determined without any instruments or fixtures. This can be done if you read the label correctly. This is not a reliable method, but in some cases it can be useful.

When working in modern homes, the rules for such labeling are usually followed.

So what are they:

1. The wire where the phase is, usually brown or black in color.
2. Null, It is customary to designate a wire that has a blue color.
3. Green or yellow the wire that is used for grounding is indicated.

These rules may have been different in previous time periods. Also, they may change in the future. Therefore, the described method is suitable only for preliminary testing of the purpose of the wires.

How to distinguish between grounding and neutral wire when the phase is off?

Assume that there is no current in the network. Is there any difference in this case between ground and neutral wire? At first glance, it may seem that they are very similar to each other.

In fact, their functions are still different. Grounding is intended for emergencies. Through it, the electric charge goes to the ground. The neutral wire is part of the electrical circuit for powering household electrical appliances in the house.

Here, current, unlike grounding, is present. How can you tell them apart? With the phase off, you just need to measure the current between this wire and a known ground. If this is a neutral wire, then the current, although small, will be in this case. If there is grounding, then there can be no current here.

In what cases may be needed?

With a huge variety of existing electrical appliances, there is a difference in what kind of electrical power they need. In different cases, such issues are resolved in different ways.

Sometimes, special devices are used for this - adapters. In some cases, it is only necessary to make the right connection to the outlet. In particular, when connecting an electric stove, there is a need to correctly determine when connecting where the phase is in the outlet, and where is the “working zero”.

In this, and in similar cases, it is impossible to do without such information.

Another situation where it is necessary is various kinds of repair work. When conducting them, you need to know exactly which wire is energized (it must either be disconnected or securely insulated), and which one is not.

When connecting many household appliances, it really doesn’t matter which side the phase is on, but for the switch it may matter. Let's explain this. "Phase" should be fed to the switch, and "zero" let it be connected directly to the lamps in the chandelier.

At the same time, in the process of replacing the lamp in the chandelier, with the switch turned off, a person will not be shocked even if he accidentally touches it.

Very often, when performing repair or installation work related to electricity in an apartment, house, garage or cottage, it becomes necessary to find zero and phase. This is necessary for the correct connection of sockets, switches, lighting fixtures. Most people, even if they do not have a special technical education, imagine that there are special indicators for this. We will briefly review this method, and also tell you about another device that no professional electrician can do without. Let's talk about how to determine the phase and zero with a multimeter.

The concepts of zero and phase

Before determining phase zero, it would be nice to remember a little physics and figure out what these concepts are and why they are found in the outlet.

All electrical networks (both domestic and industrial) are divided into two types - with direct and alternating current. We remember from school that current is the movement of electrons in a certain order. With direct current, electrons move in one direction. With alternating current, this direction is constantly changing.

We are more interested in the variable network, which consists of two parts:

• The working phase (generally referred to simply as the “phase”). It is supplied with operating voltage.
• An empty phase, called "zero" in electricity. It is necessary to create a closed network for connecting and operating electrical appliances, it also serves to ground the network.

When we turn on devices in a single-phase network, it is not of particular importance where exactly the empty or working phase is. But when we install electrical wiring in an apartment and connect it to a common house network, you need to know this.

The difference between zero and phase in the video:

The simplest ways

There are several ways to find phase and zero. Let's consider them briefly.

According to the color performance lived

The simplest, but at the same time the most unreliable way, is to determine the phase and zero by the colors of the insulating sheaths of the conductors. As a rule, the phase core has a black, brown, gray or white color design, and zero is made blue or blue. For you to be aware, there are also green or yellow-green conductors, as protective earth conductors are designated.

In this case, no devices are needed, they looked at the color of the wire and determined whether it was phase or zero.

But why is this method the most unreliable? And there is no guarantee that during the installation, the electricians observed the color marking of the cores and did not mix anything up.

Wire color coding in the following video:

indicator screwdriver

A more truthful method is to use an indicator screwdriver. It consists of a non-conductive housing and a built-in resistor with an indicator, which is an ordinary neon light bulb.

For example, when connecting a switch, the main thing is not to confuse zero with a phase, since this switching device only works to break the phase. Checking with an indicator screwdriver is as follows:

1. Turn off the general introductory machine for the apartment.
2. Strip the tested cores from the insulating layer by 1 cm with a knife. Move them apart at a safe distance to completely eliminate the possibility of contact.
3. Apply voltage by turning on the introductory machine.
4. Use the tip of a screwdriver to touch the bare conductors. If at the same time the indicator window lights up, then the wire corresponds to the phase. The absence of glow indicates that the found wire is zero.
5. Mark the desired core with a marker or a piece of electrical tape, then turn off the general machine again and connect the switching device.

More complex and accurate checks are performed using a multimeter.

Phase search with an indicator screwdriver and a multimeter on the video:

Multimeter. What is this device?

A multimeter (electricians also call it a tester) is a combined instrument for electrical measurements, which combines many functions, the main ones being an ohmmeter, ammeter, voltmeter.

These devices are different:

• analog;
• digital;
• portable lungs for some basic measurements;
• complex stationary with a large number of possibilities.

Using a multimeter, you can not only determine the ground, zero or phase, but also measure the current, voltage, resistance in the circuit section, check the electrical circuit for integrity.

The device is a display (or screen) and a switch that can be set to various positions (there are eight sectors around it). At the very top (in the center) there is an “OFF” sector, when the switch is set to this position, it means that the device is turned off. To perform voltage measurements, you will need to set the switch to the "ACV" (for alternating voltage) and "DCV" (for direct voltage) sectors.

The multimeter kit includes two more measuring probes - black and red. The black probe is connected to the lower socket marked "COM", this connection is permanent and is used when making any measurements. The red probe, depending on the measurements, is inserted into the middle or upper socket.

How to use the device?

Above, we examined how to find a phase wire using an indicator screwdriver, but it will not work to distinguish between zero and ground using such a tool. Then let's learn how to check the wires with a multimeter.

The preparatory stage looks exactly the same as for working with an indicator screwdriver. When the voltage is off, strip the ends of the wires and be sure to separate them so as not to provoke accidental contact and a short circuit. Apply voltage, now all further work will be with a multimeter:

• Select an AC voltage measurement limit above 220 V on the instrument. As a rule, there is a mark with a value of 750 V in the "ACV" mode, set the switch to this position.
• The device has three sockets where measuring probes are inserted. Let's find among them the one that is marked with the letter "V" (that is, for measuring voltage). Insert a dipstick into it.

• Touch the probe to the stripped wires and look at the screen of the device. If you see a small voltage value (up to 20 V), then you are touching the phase wire. In the case when there is no indication on the screen, you have found zero with a multimeter.

To determine the "earth", clean a small area on any metal element of home communications (this can be water or heating pipes, batteries).

In this case, we will use two sockets "COM" and "V", insert the measuring probes into them. Set the device to the "ACV" mode, to a value of 200 V.

We have three wires, among them you need to find the phase, zero and ground. With one probe touch the cleaned place on the pipe or battery, with the second touch the conductor. If a reading of the order of 150-220 V is displayed on the screen, then you have found a phase wire. For a neutral wire with similar measurements, the reading fluctuates between 5-10 V, when you touch the "ground" nothing will be displayed on the screen.

Mark each core with a marker or electrical tape, and to make sure that the measurements taken are correct, now take measurements relative to each other.

Touch the phase and neutral conductors with two probes, a figure within 220 V should appear on the screen. The phase with the ground will give a slightly lower reading. And if you touch zero and ground, then the screen will display a value from 1 to 10 V.

A few rules for using a multimeter

Before you determine the phase and zero with a multimeter, read a few rules that must be observed when working with the device:

• Never use the multimeter in a humid environment.
• Do not use defective test leads.
• While measuring, do not change the measurement limits or change the switch position.
• Do not measure parameters whose value is higher than the upper measuring limit of the instrument.

How to measure voltage with a multimeter - in the following video:

Pay attention to an important nuance in using a multimeter. The rotary switch must always be initially set to the maximum position in order to avoid damage to the electronic device. And already in the future, if the readings are lower, the switch is moved to low marks to obtain the most accurate measurements.

Generators that produce electricity at power plants have three windings, one of the ends of which is connected together, and this common wire is called Zero. The remaining three free ends of the windings are called phases.

Colors and designation of wires

In order to find the phase, neutral and ground wires of the electrical wiring without devices, they, in accordance with the rules of the PUE, are covered with insulation of different colors.

The photo shows the color coding of the electric cable for single-phase electrical wiring with an AC voltage of 220 V.

This photo shows the color coding of an electrical cable for 3-phase AC 380V wiring.

According to the presented schemes, wires have been marked in Russia since 2011. In the USSR, the color marking was different, which must be taken into account when searching for phase and zero when connecting installation electrical products to old electrical wiring.

Wire color chart before and after 2011

The table shows the color marking of electrical wiring wires adopted in the USSR and Russia.
In some other countries, the color coding is different, except yellow - green wires. There is no international standard yet.

The designation L1, L2 and L3 do not represent the same phase conductor. The voltage between these wires is 380 V. Between any of the phase and neutral wires, the voltage is 220 V, and it is supplied to the electrical wiring of a house or apartment.

What is the difference between N and PE wires in electrical wiring

According to modern requirements of the PUE, in addition to the phase and neutral wires, a ground wire must also be supplied to the apartment yellow - green.

Zero N and ground wire PE are connected to one grounded shield bus in the entrance of the house. But they perform a different function. The neutral wire is designed for electrical wiring, and the ground wire is designed to protect a person from electric shock and is connected to the housings of electrical appliances through the third contact of the electrical plug. If an insulation breakdown occurs and the phase enters the body of the electrical appliance, then all the current will flow through the ground wire, the fuses will blow out or the circuit breaker will trip, and the person will not be harmed.

If the wiring is laid indoors with a cable without color marking, then it is impossible to determine where the zero conductor is and where the ground conductor is with devices, since the resistance between the wires is hundredths of an ohm. The only clue may be the fact that the neutral wire is wound into an electric meter, and the ground wire passes by the meter.

Attention! Touching exposed parts of a circuit connected to an electrical outlet may result in electric shock.

Probe indicators for searching for phase and zero

A device designed to search for zero and phase is called an indicator. Light indicators for determining the phase on neon bulbs have been widely used. Low price, high reliability, long service life. Recently, indicators have also appeared on LEDs. They are more expensive and additionally require batteries.

On a neon light

It is a dielectric case, inside of which there is a resistor and a neon light bulb. Touching in turn to the wires of the electrical wiring with the screwdriver end of the indicator, you find the phase by the glow of the neon bulb. If the light bulb lit up from touch, then this is a phase wire. If it does not glow, then this is a neutral wire.

Cases of indicators come in different shapes, colors, but the filling is the same for all. To prevent accidental shorting, I advise you to put a tube of insulating material on the screwdriver shaft. Do not use the indicator to unscrew or tighten the screws with great force. The indicator case is made of soft plastic, the screwdriver shaft is pressed in shallowly and the case breaks under heavy load.

Probe LED indicator

A probe indicator for determining the phase on LEDs appeared relatively recently and are gaining more and more popularity, as they allow not only to find the phase, but also to ring the circuits, check the health of incandescent bulbs, heating elements of household appliances, switches, network wires and much more. There are models with which you can locate the electrical wire in the walls (so as not to damage when drilling) and find, if necessary, the place of their damage.

The design of the LED indicator-probe is the same as on the neon light bulb. Only instead of it, active elements are used (a field-effect transistor or a microcircuit), an LED and several small-sized DC batteries. Batteries last for several years.

To find the phase with the LED indicator-probe, its screwdriver end is touched sequentially to the conductors, while you can’t touch the metal platform at the end with your hand. This site is used only when checking the integrity of electrical circuits. If, when searching for a phase, you touch this site, the LED will also shine when the indicator touches the neutral wire!

A brightly lit LED will indicate the presence of a phase. According to the rules, the phase wire should be on the right side of the outlet. How to check contacts and circuits with such a probe indicator is described in detail in the instructions attached to it.

How to make a test indicator yourself
to search for phase and zero on a neon light bulb

If necessary, you can make a probe indicator with your own hands to search and determine the phase.

To do this, you need to one of the conclusions of any neon light bulb, even a starter from a fluorescent lamp, solder a resistor with a nominal value of 1.5-2 MΩ and put an insulating tube on it.

A light bulb with a resistor can be placed in a screwdriver handle or a ballpoint pen case. Then the appearance of a home-made indicator-probe will differ little from the industrial design.

The search or phase determination is performed in the same way as with an industrial probe indicator. Holding the light bulb by the base, touch the conductor with the end of the resistor.

When choosing a resistor, sometimes it is difficult to determine its value if colored rings are applied to the resistor body instead of a number. An online calculator will help you with this task.

Why is the indicator glowing
when touching the neutral wire

I have been asked this question many times. One of the reasons is the incorrect use of the LED indicator. How to properly hold the LED indicator-probe when searching for a phase is written in the article above.

The second possible reason for this behavior of the indicator is a break in the neutral wire. For example, the circuit breaker, installed after the meter on the neutral wire, worked. In old apartments, this is not uncommon and is a gross violation of the arrangement of electrical wiring. It is mandatory to remove the machine from the neutral wire or short-circuit its outputs with a jumper.

When the neutral wire breaks, a phase enters it through the devices connected to the mains, for example, through the switch backlight indicator, TV in standby mode, any charger that is turned off only by the start button, the computer and other electrical appliances, the phase arrives. The indicator shows this. In this case, the neutral wire can be dangerous and touching it is unacceptable. It is necessary to find and eliminate a break in the neutral wire, which can also be located in junction boxes.

How to find phase and zero using an electrician's control

To check the presence of supply voltage in the electrical network, earlier electricians used a home-made control, which is a low-power incandescent bulb screwed into an electric socket. Two conductors of stranded wire about 50 cm long are connected to the cartridge.

In order to check the presence of voltage, you need to touch the conductors of the control to the wires of the electrical wiring. If the light is on, there is voltage.

Checking an electrician on a light bulb requires careful handling and takes up a lot of space. It is much more convenient to make an electrician's control on the LED according to the diagram below.

The circuit is simple, in series with any LED, a current-limiting resistance is switched on. LED of any type and color of glow. Use it in the same way as an electrician's control on a light bulb.

The LED and resistor can be housed in a suitably sized ballpoint pen case. In the photo is a control for a motorist. The scheme of such control is the same. Only depending on the type of LED used, the resistor R1 is set to a value of about 1 kOhm.

It is easy to check the presence of voltage on the wires in the vehicle's on-board network with such a control, the right end is connected to ground according to the diagram, and the left end touches any contact. If there is voltage on the contact, the LED will light up. If you touch the positive terminal of the battery with one end of the fuse, and touch the other with the control, then if the LED does not light, then the fuse is open. So you can check both incandescent bulbs and the presence of contact in the switches.

Phase search in the presence of neutral and ground conductors

If you want to find a phase in the wiring, which has phase, neutral and ground wires, then using the control it is easy to do. It is enough to perform three touches with the control wires. It is necessary to assign a conditional number to each wire, for example 1, 2 and 3, and in turn touch the pairs of wires 1 - 2, 2 - 3, 3 - 1.

The following behavior of the light bulb is possible. If, when you touch 1 - 2, the light does not light up, then the wire is 3-phase. If it shines when you touch 2 - 3 and 3 - 1, then it is 3-phase. The meaning is simple, when you touch the neutral and ground conductors, the light bulb will not shine, since in practice these are conductors connected together on the shield.

Instead of control, you can turn on any AC voltmeter, designed to measure voltages of at least 300 V. If you touch the phase wire with one voltmeter probe and the zero or ground wire with the other, the voltmeter will show the mains voltage.

Search for phase and zero by control

Attention, touching any bare conductors while searching for a phase with a control can result in electric shock.

Everything is done very simply, one end of the control wire is connected to a central heating or plumbing pipe stripped to metal, and the other in turn touches the wires or electrical wiring contacts. When you touch the phase wire, the bulb will light up.

If the metal of the pipe cannot be reached, then you can use the water flowing from the mixer. To do this, turn on the water and place one control wire under the stream of water as close as possible to the mixer. The second end of the wire touches the wires of the electrical wiring. The weak light of the bulb will tell you where the phase is.

It is best to screw the smallest light bulb into the control box, I used a 7.5 W refrigerator light bulb. In order to reach the water, you can use a piece of any wire or a standard extension cord.

Search for phase and zero with a voltmeter or multimeter

Finding the phase with a voltmeter or multimeter is carried out in the same way as with an electrician's control, only the probes of the device are connected instead of the ends of the control.

To determine zero in a three-phase network using a tester or multimeter, it is enough to measure the voltage between the wires, which will be 380 V between the phases, and 220 V between zero and any of the phases. That is, the wire relative to which the voltmeter will show 220 V on the other three and there is zero.

Finding phase and zero with potatoes

If you don’t have the technical means to find the phase at hand, then you can successfully use an exotic or folk, you can’t call it otherwise, method for determining the phase, using potatoes. Don't think this is a joke. For some, this may be the only available method that can be successfully applied in practice.

The end of one conductor must be connected to a water pipe (if it is not plastic) or a radiator. If the pipe is painted, then the connection point must be cleaned to metal in order to ensure electrical contact. Insert the opposite end into the potato slice. The other conductor is also stuck with one end at the maximum distance from the previous one into the potato, with the second end through a resistor with a nominal value of at least 1 MΩ, they touch the electrical wires in turn. Some time to wait. If there is no reaction on the cut of the potato, this is zero, if there is, it is a phase. I do not recommend using this method if you do not know the safety rules for working with electrical installations.

As you can see, in the photo around the wires, when the electrical wiring was connected to the phase wire, changes occurred on the cut surface of the potato. When you touch the neutral wire, there will be no reaction.