How to determine the phase with an indicator screwdriver. How to determine the phase and zero without devices: we determine where the phase is where the zero is through the wires and with an indicator screwdriver. Using a phase tester

When working with household electrical networks, you need to know how to find the phase and zero. The usual 220 volts do not come out of nowhere.

The entire low-voltage network (meaning the value, for consumers) is three-phase. The voltage between the phases is variable, 380 volts.

For domestic needs, a voltage of 220 volts is used. In order not to go into the trigonometric details of building three phases, it is enough to know the formula: the voltage between the phase and zero is equal to the voltage between the phases, divided by Square root pi numbers. That is, if there are 380 volts between the phases, then the voltage between the phase and zero will be 380 / 1.73 = 220 volts.

Why is it necessary to know where is zero and where is the phase?

Many users household appliances believe that there is no difference how to connect electrical appliances to a 220 volt variable network. There is no polarity, the voltage does not change when changing contacts. This is true from the point of view of simply plugging into an outlet.

And if you yourself do the wiring or repair of the electrical network in your house, you need to know exactly where is zero and where is the phase.

1. When designing electrical panels, single-contact machines are used. Only a phase starts on them. The zero line remains unopened. Each line is connected with one wire to the phase through the switch, and directly to the zero line;

Important! If you confuse zero and phase with such a connection, it will be life-threatening to use the network.

2. Lighting devices are powered in a standard way, using single-phase switches. Only the phase wire opens, zero is always connected to light fixture. If you confuse zero and phase, simple replacement light bulbs can cause injury electric shock.

Therefore, it is necessary to track the phase and neutral wires along the chain from the meter to each consumer.

Several ways to determine phase and zero

Method number 1, using a tester capable of measuring voltages up to 1000 volts. This is a reliable method, but for verification it is necessary to have a well-connected ground wire. In the apartments of the old design it is not.

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 electric cable for single-phase wiring with voltage alternating current 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 wires electrical wiring 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 to the apartment except for the phase and zero wires, a ground wire must also be connected yellow - green.

Zero N and ground wires 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! Exercise extreme caution when working on live electrical wiring. Touching an unprotected part of the human body to the phase wire can cause serious damage to health, up to cardiac arrest.

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 term services. 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 are different forms, flowers, but the filling is the same for everyone. To prevent accidental short circuit, I advise you to put a tube of insulating material. Do not use the indicator to unscrew or tighten the screws with great force. The indicator housing is made of soft plastic, the screwdriver shaft is not pressed deep and the housing breaks under greater 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 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.

Design LED indicator- probe, the same as on a neon light bulb. Only active elements are used instead ( field-effect transistor or microchip), LED and several small batteries direct current. 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 for integrity checks. 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 must be with right side sockets. 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 lamp daylight, 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 housing from ballpoint pen. 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 not correct application 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 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. Required in without fail remove the machine from the neutral wire or short-circuit its outputs with a jumper.

If the neutral wire breaks through the devices connected to the mains, for example, through the switch backlight indicator, the TV is in standby mode, any Charger, 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, electricians previously 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.

LED and resistor can be placed in a ballpoint pen case right size. 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 zero and ground conductors, the 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 when searching for a phase with a control can cause irreparable harm to your health!

Everything is done very simply, one end of the control wire is connected to a pipe stripped to metal central heating or plumbing, while others in turn touch the wires or contacts of the electrical wiring. 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 the control of an electrician, only instead of the ends of the control, the probes of the device are connected.

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

Finding phase and zero with potatoes

If you don't have on hand technical means to search for a phase, 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 which can be successfully applied in practice.

The end of one conductor must be connected to water pipe(if it is not plastic) or a heating battery. 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.

It is not always rational to resort to the help of a multimeter to determine the phase and zero of the network at home. And the cost of complex equipment is much higher. There is a more simplified device that allows you to perform these functions. This is an indicator screwdriver. She happens to be simple instrument. However, when working with electricity, it is necessary to follow all safety rules, no matter what equipment is used.

The design of the indicator screwdriver

The principle of indicator screwdrivers is quite simple and outwardly resembles its usual counterpart. The difference between them is in the handle.

The indicator screwdriver has a resistor in the case, to which the metal tip of the tool is connected. It acts as a conductor.

The resistance element reduces the current to the maximum possible value. This allows you to use the indicator screwdriver safely.

The case also contains a small LED or neon bulb. It connects to the outer patch of the contact plate, which is located on outside screwdrivers.

The current passing through the probe and resistor decreases, its strength becomes safe for work.

This is the basic principle of operation of such a device as an indicator screwdriver. How to use the device, tell the rules.

The person must touch the plate on the outer edge of the instrument. The circuit in this case will be closed and the indicator light will be activated.

Phase and zero in a screwdriver

To connect a wire to electrical equipment, you should know how to determine the phase and zero with an indicator screwdriver. The current that feeds the devices always goes through the first wire - the phase. The second wire is zero. Electricity passes through it reverse direction and returns to the power source.

When the probe touches the screwdriver bare wire indicator lamp lights up. If this does not happen, then this is a zero cable.

The wire must be energized. Otherwise, it will be impossible to determine the phase and zero with a simple indicator screwdriver.

The absence of voltage on both wires when the network is on indicates a break in the conductor section.

Application area

The presented tool will be able to perform not only the most simple functions- how to determine the phase with an indicator screwdriver - but also many additional ones.

It is possible to check the cable for a break, the serviceability of the extension cord, to detect the wiring in the wall.

All functions must be carried out specific instruction applications indicator screwdriver. Measurements can be made by contact or non-contact method.

The contact method will help you find the voltage in the AC mains. This is the simplest procedure. The probe of the tool touches the bare cable. If the LED lights up, then a phase has been found. In the case when the indicator does not light up, it may be a neutral wire, and this also happens when there is no power supply or its breakage.

The contactless method will help you find concealed wiring. To do this, the handle is brought to the surface behind which the wire is located. If the neon element lights up, the conductor is found.

Types of indicator screwdrivers

Variants of screwdrivers with indication are different in their functionality.

Indicator screwdrivers without a battery will allow you to find only the phase of the network.

The presented models are the simplest, most reliable and are widely used to determine the voltage in networks of residential buildings.

Limiting the minimum current level to 60V makes the tool unsuitable for working with low-power systems.

There are models of the device with a battery, which allows you to determine non-contact network parameters such as zero and phase. An indicator screwdriver of this type will allow you to determine the integrity of the electrical wire. The device will test the cable even without power supply.

A universal indicator screwdriver will allow you to determine the zero and phase in both contact and non-contact ways. Can be used in low voltage networks.

Checking the device before operation

Before starting the process, it is important to familiarize yourself with the rules on how to check the indicator screwdriver. For this, it is produced visual inspection on the integrity of the structure in order to exclude the presence of mechanical damage.

Having completed this action and found no deviations from the norm appearance tool is being tested.

When checking, the probe of the indicator screwdriver is inserted into each hole of the working socket. Thumb in this case, it is necessary to keep the handles of the dielectric sensor on the plate. If this is not done, the indicator will not work.

Also, when using equipment with a neon indicator on a battery, it is permissible to simply pinch the tip of the screwdriver and its snout with your fingers. If the LED lights up, the tool is OK.

Security measures

In order for the work to be safe and no unpleasant surprises occur, you should familiarize yourself with the rules for use, which determine the indicator screwdriver. The instruction stipulates the following precautions.

1. It is forbidden to use the device without a screw.
2. Only the battery can be removed from the device.
3. After replacing the battery, the screw is tightly twisted clockwise.
4. Do not use a tool with mechanical damage.
5. It is forbidden to use a screwdriver when high humidity environment.
6. It is strictly unacceptable to use the device for networks with inappropriate voltage.

This row is enough simple rules, however, their strict implementation guarantees the preservation of health and ensures the safety of activities.

User manual

Many functions will allow you to perform an indicator screwdriver. How to use it correctly? Rules have been developed to govern this.

In order to assess the wire for a break, the probability of a lack of voltage in the network should be eliminated. Then, holding the wire with one hand, you should touch the sting of the other end.

If the wire is good, the LED will glow.

With this device, you can check the condition of the extension cord. To do this, the conductor is disconnected from the network. Two wires are inserted into both holes of the socket. Holding the contact of the plug, you should check the second contact with the tool.

If the light turns on, the extension cord is good.

Finding a cable break is also quite simple. The probe of the tool is clamped with fingers, and its handle is drawn along the cable. Where the indicator stops burning, there is a break in that place.

Battery replacement

An indicator screwdriver, the design of which provides for a removable battery, will eventually require its replacement.

In order to avoid damage and ensure the safety of operation of the device, this operation should be carried out according to certain rules.

The battery is replaced at the moment when the LED stops working during the test.

The most commonly used batteries for an indicator screwdriver are marked LR41, AG3, 392A, V3GA, G3-A.

When replacing, unscrew the screw at the end of the handle. It holds the battery in place with a small spring.

The wire holding the battery is bent and replaced.

Then the ears of the holders are gently and tightly pressed into their original position.

The handle screw must be tightened well. It is strictly forbidden to use the tool without this part or if it is poorly closed.

When repairing electrics or replacing its elements at home, you need to choose the most suitable type tool. An indicator screwdriver will help determine the phase and zero of the network, as well as the place of its break.

When using the device, following all the operating rules provided for in the instructions, you can guarantee the safety of the work performed. Responsible attitude to use, battery replacement will ensure the health of the user. Pretty simple and handy tool will allow you to perform the most common actions with the elements of the electrical network at home.

Check functionality electrical networks in an apartment or a private house can be different ways. From a financial point of view the best option there will be an indicator probe that can replace a multimeter at home.

While doing installation work with sockets and light switches, it is often necessary to find the phase and zero. Of course, for experienced electricians, such a task is a trifle, but for those who are not familiar with the rules of the device electrical networks, this question can drive into a dead end.

indicator screwdriver. Nuances in use

Considering the number of electrical appliances in each apartment, everyone should have this device. With it, it will be possible to determine the presence of current in any conductor, socket or electrical panel.

The design of the indicator screwdriver

The design of an ordinary probe in the form of a screwdriver is simple:

• probe, acts as a conductor;
• a resistor is connected to the sting, it is needed to lower the current strength to a value that is safe for the human body;
• then there is an LED that is connected to the contact patch brought to the end of the screwdriver;
• body is made from transparent plastic, this allows you to see the LED lighting up.

Phase and zero in a screwdriver

Finding the phase and zero with an indicator screwdriver is not difficult. When the probe touches a live wire, the current will pass through the rod, then through the resistor, cause the LED to glow, and then fall on the hand that touches the metal plate. The current will also pass through the body of the person who performs this operation, and then leave the ground.

The person himself will not feel the current passing through him, since its value is too small.

Application area

Any work that relates to electrical wiring must be safe. For this purpose, everyone should have this necessary tool in the house.

This device can be used for the following purposes:

• check to which contact of the socket or switch the phase conductor is connected;
• when the extension cord outlet is not working, you can check all the sockets with a probe;
• with its help, you can find out where the phase is connected in the cartridge: to the central contact or to the thread;
• find out if the electrical appliance is energized;
• by touching the tip of the tool to the central contact of the socket, you can check the serviceability of the grounding conductor.

Important! If the mains is AC, then there is no need to press your finger against the plate!

Screwdriver types

New models of screwdrivers can detect the presence of stress in the strand even through a layer of whitewash, plaster and clay. Their algorithm of action is almost always the same. But there are also differences that arise depending on the types, models and a number of functions that the tool has.

Sometimes, in terms of its functionality, one screwdriver can replace several expensive devices. There are devices with a battery, this makes it possible to check the health of the wire, even in a de-energized state.

Important! Any indicator screwdriver has lower and upper voltage measurement limits. Exceeding them may break the device or display incorrect information.

Such a model can give maximum amount interesting information about the circuit under study:

• a beep will indicate that there is voltage in the circuit;
• the digital display will display the voltage value in volts;
• makes it possible to check AC and DC circuits in household electrical appliances;
• determine the polarity of the networks;
• with its help, you can carry out the continuity of the electrical circuit with a light or sound indication.

Checking the device before use

Before use, the indicator device must be checked for serviceability. The battery that is inside the device will help make sure of this. You will need to touch the sting and the other finger to the metal contact on the handle at the same time. The indicator light should light up at this point.

If the device does not provide for a battery, then a live conductor is needed. You need to touch it with the tip of a screwdriver, and the metal on the handle with your finger. As a result, the LED will also glow.

Basic Security Measures

Be sure to follow the precautions:

• it is forbidden to use a probe without a screw;
• only batteries can be removed from the device;
• after the battery is replaced, the screw should be tightened clockwise until it stops;
• if the probe has mechanical damage, then its use is prohibited;
• do not use the device above the limits specified in the technical specifications;
• before using the probe, you will need to check it in the network with the exact presence of a phase;

Important! When measuring electrical lines, the probe is held only by insulated elements. Exceptions are circuits without voltage.

Instructions for use

According to their characteristics, such indicator devices are intended for:

• the ability to determine the alternating voltage by contact method up to 250 V;
• non-contact method up to 600 V;
• examination of the circuit for integrity from 0 to 2 MΩ;
• establishing polarity: from 1.5 V to 36 V;
• the tool must be stored in a dry and moisture-protected place;
• all operations are best done with gloves to ensure contactless examination;
• after work, the tool should be cleaned of dust and debris.

Non-contact screwdrivers are very sensitive, it can respond to both phase and neutral, although the real voltage will be in only one wire. Therefore, for an ordinary electrician, such a screwdriver is not needed. However, it can help in checking the quality of cable shielding and the absence of radiation.

In such devices, there are three switch positions. Two are provided for remote action. In the event that a screwdriver accidentally touches the current-carrying part of the wire in this mode, the entire electronic part, consisting of transistors and an LED, will burn out.

Electrical appliances surround a person in Everyday life. Sooner or later in any electrical system problems and problems occur. These problems are not always worth inviting an experienced electrician; some breakdowns can be fixed on your own. However, to be able to find a fault in the network, you will definitely need special tool, which costs, purchase in advance.

Installation of internal wiring, self-installation 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 possible ways and rules safe work with electricity. We have devoted today's article to the solution of these issues.

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 are used (in modern houses- three) wires. 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 would an ordinary resident of a high-rise building or country house it is necessary 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 repair lighting device without power outage throughout the apartment. In addition, installation of a socket for connecting various household appliances, especially those whose work is associated with the use of running water, as well as having 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 involving professional electrician. The first of them involves the use of the so-called probe, or phase indicator. It is a small flat head screwdriver plastic handle, in which a light signaling device is enclosed - 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 only happen when correct use device - one of the fingers of the hand in which you hold the device should 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 coding depending on their purpose. So, to connect to the phase, a black or brown conductor should be used, to zero - blue or blue, and the grounding conductor should be painted partially in yellow and partly in green.

Unfortunately, the peculiarities of our country and many irresponsible electricians often lead to ignoring 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 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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