How to determine phase and zero with an indicator screwdriver or multimeter. Determining phase and zero: overview of methods What phase or zero lights up

Before you begin the process of determining phase and zero, it is necessary to make a number of preparations, since the following devices and tools will be required for this work:

• multimeter;
• tester;
• pliers;
• a knife with a sharpened blade to remove insulation from conductors;
• insulating tape;
• marker for marking;

It is also important to remember that before starting any electro installation work, you need to turn off the machines, since non-compliance of this rule may pose a threat to life. In addition, you must ensure that all tools used have properly grounded handles.

Otherwise, its use is unsafe and is not permitted due to safety regulations.

Visual method of determination

This technique is the most in a simple way, since its implementation does not require any additional devices or equipment.

It is necessary to inspect the wiring; most often it has the following color distinctions:

1. Yellow-green wire is grounding.
2. Zero is blue or any shades of it up to light blue.
3. The phase is black, brown or white.
4. You need to make sure color matching not only in the electrical panel, but also in the distributor.

A visual inspection of the system must be carried out in accordance with the following algorithm of actions:

1. Open the electrical panel and inspect its contents. Since the design load may vary, the number of installed machines may also vary. Through them, a phase or phase with zero can be connected; grounding is never connected to, but is connected to the bus. Make sure that all connected wires match the color code.
2. If the insulation color, carried out from the electrical panel to the home network, complies with the rules of color marking, then it will still be necessary to open the distributors for visual inspection of the twists. This is necessary in order to make sure that in them the color marking of the zero and ground insulation was not confused and complies with the established rules.
3. Sometimes in distributors the phase is connected to circuit breakers. In most cases, this is realized using a special wire with two cores, the insulation of which may differ in color.
4. If the visual inspection results have shown that the insulation colors fully comply with the rules, then all that remains is to check the phase conductor using an indicator screwdriver.

Determination with an indicator screwdriver

One of the simplest ways to determine zero and phase is to use an indicator screwdriver for this purpose.

To carry out this process, you must adhere to the following algorithm of actions:

1. Initially You will need to turn off the circuit breaker that supplies power to the power line at the test site.
2. Clean up of both conductors being tested, it is enough to remove no more than 1-2 cm of the insulating layer.
3. After that both conductors are separated from each other by safe distance, since after voltage is applied, their accidental contact may cause a short circuit.
4. You can start to the identification of the phase conductor. To do this, the automatic machine turns on and supplies voltage, after which you will need to take an indicator screwdriver and touch the metal area located near the base of the handle.
5. Strictly not allowed touch any part of the indicator screwdriver below the handle as this will cause electric shock.
6. Touch the tool to one of the wires being tested, without removing your finger from the metal area.
7. Light bulb coming on, included in the design of the screwdriver, indicates that the conductor is phase. Accordingly, the second wire is zero. If the light bulb did not light up, on the contrary, the conductor was zero, and the second is a phase.

Determination with a tester or multimeter

Another common way to determine phase and zero is to use special devices– tester or multimeter.

If this option was chosen, then you must adhere to the following sequence of actions:

1. Device used set limit measurement settings alternating current. On modern models This parameter corresponds to ~V or ACV mode. It is necessary to specify a value equal to 600 V, 750 V, 1000 V or another parameter depending on the characteristics of the model, the main requirement is that it exceeds 250 V.
2. Instrument probes it is necessary to touch both wires at once in order to determine the voltage level between them. In standard household networks, this figure is 220 V; the possible deviation should not exceed 10% in either direction. Similar meaning indicates that the conductor is a phase; at zero the voltage level will be very insignificant or equal to zero.
3. In modern electrical networks It may also be necessary to identify the grounded conductor, which requires determining the resistance level. In this case, the device is switched to the appropriate mode, which has symbol in the form of a bell or omega icon.
4. Must be remembered that when the device is switched to the mode for determining the resistance level, it is strictly prohibited to simultaneously touch the phase and ground, as a short circuit will occur. There is a risk of injury.

Definition by labeling

When describing the visual method of identifying conductors, it was clarified that in most modern electrical networks the yellow-green color corresponds to a protective zero, all shades of blue color indicate the working zero, and any other colors indicate the phase.

However, it must be taken into account that conductors may not correspond to the accepted color scheme in the following cases:

1. Wiring installed in the house old building , where the home electrical network was not reconstructed in accordance with modern rules. Most often, it uses single-color conductors.
2. Wiring installed in a new building, but its installation was carried out by private individuals and not by professional electricians.
3. Wires lead to more complex household devices, for example, various switches or switches, the design of which initially implies a fundamentally different operating scheme.
4. Wiring was laid according to standards, different from those accepted in Europe, so it has completely different color designations.

In most other cases, color marking of conductors is carried out in accordance with the specified rules, which are regulated by the relevant IEC standard, valid throughout Europe.

In situations where there is no complete confidence in full compliance color range generally accepted standard, it is recommended to use one of practical methods to determine zero and phase.

Also, we can advise you to subsequently use special colored attachments, which will allow you in the future not to forget the purpose of the conductors and not to carry out the procedure for identifying them again.

Determination using potatoes

One more known method determination without special devices is an option that uses ordinary raw potatoes. Many experts are quite skeptical about such actions, but such a solution is still effective.

To implement it, it is necessary to carry out the following sequence:

1. Take one raw potato and cut it into two parts.
2. Clear ends of two conductors and stick them into one of the parts of the potato.
3. Wait about 10 minutes, then pull out both wires.
4. Inspect the potato: in the place where the greenish trace formed, a phase conductor was stuck.

Other methods of determination

There are several alternative methods for determining phase and zero; they are rarely used and are often criticized by qualified specialists. This is mainly due to the fact that similar methods are more dangerous, so they must be carried out with maximum degree caution.

One of these determination methods requires the use of a conventional computer cooler; it can be used in practice in cases where the parameters of the supplied voltage are known, but the purpose of the conductors is unknown:

1. For implementation you will need to use the red and black wires coming out of the fan. Sometimes it also has a third wire, which is a speed sensor, but it is not useful in the determination process.
2. Red cooler conductor is phase, and black corresponds to zero.
3. Standard fans are designed for 12 V, and begin to function from 3 V, so they are best suited for testing from appropriate power sources.
4. If the voltage exceeds 12 V, then you will need to sharply touch the conductors to the cooler terminals and look at the reaction of the blades. If they remained motionless, then a zero was connected to the red conductor; if they began to move, then it was a phase.

For another method of determination, a control lamp will be needed, and its implementation will require compliance with the following algorithm of actions:

1. Initially you need to assemble the test lamp itself, the simplest device will look like this: screw the light bulb into the socket, secure the conductors into it, remove the insulating layer from their ends.
2. Further process does not present any difficulty: the tested conductors are alternately connected to the contacts of the lamp, during the process it is necessary to observe its reaction.

Among the safer determination options are the following alternative methods:

1. Checking conductors through an RCD, since it is known that in the presence of a consumer connected to the electrical network, a short circuit between zero and ground contributes to the occurrence of electric current leakage, which immediately turns off protective device. This will help identify the neutral and grounding conductor, the third will be the phase.
2. Take the fuse and grab it with pliers, the handle of the tool must be insulated to avoid. Close two conductors on it and check the result: if the fuse is blown, then it was phase and ground; if it survived, then earth and zero or phase and zero. By performing several successive experiments and recording the results, it will be possible to accurately identify each conductor.

Features of determining phase and zero

On a two-wire network

Identification of conductors in a two-wire network is much simpler, since it is carried out in the simplest way; this will require:

1. Determine phase only, since it is known that the second conductor will be zero.
2. To determine the phase In a two-wire network, an indicator screwdriver is ideal; the detailed procedure was described above.

On a three-wire network

A little the situation is more complicated the situation with modern types three-wire networks, since they also have grounding.

To determine the purpose of the conductors, you must adhere to the following algorithm of actions:

1. Phase determined using an indicator screwdriver using the method described above. After this, it is recommended to mark it with a marker so as not to mix up the wire in the future.
2. For working with zero and ground You will need to use a multimeter. The neutral conductor may also have voltage, which is caused by phase imbalance, but its readings never exceed 30 V. The multimeter must be switched to the operating mode to measure AC voltage, after which one probe is connected to the phase, and the second one in turn to the remaining conductors. Zero will be where the lowest voltage parameter is recorded.
3. Sometimes both conductors have the same voltage ratings. In this case, the phase must be isolated and the multimeter switched to a mode designed to determine the resistance level. Also, you will need to select an external grounded element and touch it with one probe of the device, and the second in turn to each of the conductors being tested. In the case when the multimeter shows a resistance of 4 ohms or less, the connection is made to ground; if the reading is higher, then it is zero.
4. However, resistance figures are not accurate and, if the neutral was subject to grounding while still inside the electrical panel. Then you will need to detect and disconnect the grounding element that is connected to the bus. After this, take a test lamp and perform the previously described experiment on connecting it. It lights up only when the neutral conductor is connected.

Construction of household electrical networks

The supply of electricity to any residential buildings occurs through transformer substations, which change the incoming high-voltage voltage, and at the output it already has an indicator of 380 V.

Modern household electrical networks look and function as follows:

1. Transformer winding at the substation has a special type of connection, which gives it a resemblance to a star. Three pins are connected to one common zero point, and the other three to the corresponding terminals.
2. conclusions, connected to zero, are connected and connected to ground transformer substation.
3. In the same place the common zero is divided into a working zero and a special protective PE conductor.
4. Described system received the designation TN-S, but in older houses the TN-C scheme is still in use, which is distinguished primarily by the absence of a protective PE conductor.
5. Phase and zero, after being removed from the transformer, they are pulled to residential buildings for connection to the input electrical panel. Here a three-phase voltage system with 320/220V is created.
6. Further The wiring is carried out through access electrical panels, where voltage is supplied from the 220V phase and a protective PE conductor, if its presence was provided.
7. Zero in the apartment electrical network will be a conductor that has a connection to the ground in the transformer substation circuit and is intended to create required level load from a phase that is also connected to the transformer winding, but from the opposite side. Main function protective zero is the diversion of damage currents that may occur during emergency situation within the network.
8. Happening uniform distribution of the load, this is carried out thanks to the presence of floor wiring, as well as the connection of apartment electrical panels to certain 220 V lines inside the central distributor in the entrance.
9. System, through which voltage is supplied to residential building, accurately repeats the vector characteristics of the transformer substation and also has a star shape.
10. Sum of all currents in the three-phase variety of the electrical network, it is folded in accordance with the vector graphics inside the neutral conductor, after which it is returned to the transformer winding in the substation.

If you turn off all electricity consumers inside a living space and disconnect them from working sockets, then the electric current inside the network will stop flowing even with voltage supplied to the electrical panel.

The described system for arranging a household electrical network is the most optimal of all existing today, but it is not immune from possible malfunctions. In most cases, they are associated with broken contact connections or broken conductors.

Content:

Our household electrical network is everything to us. Especially where gas is not used for cooking - everything is electric. We are used to using electrical appliances very simply: there are sockets and switches. We turn the light on or off with one press of a button. To turn on some other device, we find an outlet, plug it in and use it. A vacuum cleaner, for example.

And most of the devices are already connected and are never pulled out of the network, like a TV. It’s also a switch, similar to a switch for a lamp or chandelier, and all switching occurs with one touch. Or even in general - the refrigerator stands on its own and turns itself on and off when it wants.

Well, this means that everything is fine on the network, and you don’t even need to know for sure that there are wires in the sockets - they are different in nature.

The voltage in our network is alternating, 220 volts, with a frequency of 50 hertz. This is how our energy system is designed. Generators provide three-phase voltage; in a sense, this is optimal for delivery to consumers. After all, if a simple sinusoidal voltage requires wiring from two conductors, then a three-phase voltage can be transmitted as a complex, with all three phases at once. But transmission requires not six wires, as you might expect, but only four. That is, one and a half times less. When transmitting over long distances, this is oh so significant for saving metal.

Our houses and apartments are supplied with three-phase voltage with an amplitude of 380 volts. But usually one phase is selected on the shield. This means that for energy consumption we need at least two wires. And one of them is called phase, and the other is called zero. This was the case with the old connection. And the old sockets were made without taking into account the connection of the third wire - grounding. Grounding has now become the norm, it should protect us from electric shock from our household appliances, if a breakdown occurred in them, and 220 volts ended up directly on the metal case or casing of the device. Therefore, it is necessary that there be grounding everywhere. It joins all non-current carrying metal structures devices, and it’s good if it is grounded as close to us as possible. This is so that the resistance between the grounded parts of the devices and the ground itself is as small as possible. Then, in the event of an emergency breakdown of the wire carrying the phase and the body of the device, the phase would immediately go into the ground without damaging us.

But it is not always the case. Previously, and even now, if there was no grounding of appliances, it was possible to determine whether, for example, an iron or refrigerator was connected to the network or not, or maybe its fuse had blown. If you ran your hand - especially the sensitive back of your elbow - and simply “stroke” the iron, touching it lightly, you felt something like a slight vibration or a slight tingling sensation. This indicated that a phase was supplied to the device, and inductive voltages were generated in the ungrounded housing.

There is nothing good in such interference in itself; they can sometimes reach 100 volts, and even sensitively “crack” a person. Depends on the mutual capacitance of phase conductors and housing parts. The refrigerator will have more, the iron will have less.

Actually, this is the first way to check the phase, although there is no need to do this - it may crack, or the focus will not work at all when there is normal grounding. And in this method it is completely unclear through which wires the zero and phase are supplied. Their presence will only be stated.

And the supply occurs through a minimum of two (phase and zero, as already mentioned here) wires, and a maximum of three. This is for a single-phase connection. And when three phases of wires are supplied to a consumer at once, there will be five. Three phases are much more serious, a voltage of 380 volts is much more dangerous - it more often leads to death, so grounding such installations is always prerequisite.

A single-phase network has one phase wire, one neutral wire and one ground wire.

The ground wire is highlighted immediately and does not need to be defined. But the phase and neutral wires in the socket can be either on the right or on the left. There is no rule by which this is precisely established. You can see by the color of the insulation of the matching wires, but they are:

• are placed under the socket cover and go secretly into the wall;
• Even if you get to them by unscrewing the screw and removing the cover, there is still no guarantee that:
  • color marking of phases is observed;
  • it was observed when they pulled the wire from the junction box.

The color designation of wires in the power network prescribes:

• blue designate the neutral wire;
• yellow-green striped - ground wire;
• a wire of a color different from these two indicates a phase (black, red, gray, purple...).

A three-phase lead is designated in exactly the same way, only the phase wires must be all different color and not be blue or yellow-green.

This is normal professional installation must be carefully observed, but... We buy apartments and move to new habitats and become owners. And we do in our apartments what we consider useful and correct and do not always care about compliance with standards. We usually remember what we did and easily find, when necessary, in a socket we installed ourselves, both the phasing and the neutral wire without an indicator. The same absolutely cannot be said about the owners who will replace us if we sell the apartment.

For these reasons, it is necessary, and not just useful, for any owner to know how to check the health of the network and how to find phase and zero anywhere in the household network. And, in addition, carry out an inspection of the entire electrical network and install the correct markings on all inspected conductors. If the standard color marking of the wires being tested is not followed, mark them with rings of electrical tape or heat shrink tubing different but standard colors. Make a special note of the locations of the faults and start correcting anything wrong that you find as quickly as possible.

Determination of phase and zero

This can be done with different devices. The simplest thing is to check the presence of a phase with an indicator. A device specifically designed for this purpose. How to determine zero when you know the phase? If everything is normal, then this is the wire where there is no phase.

The indicator is often used like a screwdriver. You can even use it to unscrew a small screw that is not very tight, but it is better not to tempt fate - this is a device, and it is better to use it for its intended purpose. It consists of a tip, from which a wire goes through a high resistance (about 1 MOhm) to a neon lamp. The other contact of the neon goes to the other side of the indicator, and when measuring, you should touch it with your finger. To test the conductor, the tip must be pressed against it. Since a person has a fairly large surface area, he is with neutralized/grounded metal surfaces The network forms a kind of capacitor. If there is an alternating voltage on the wire to which the tip is pressed, a very weak, non-hazardous current of about 0.02 mA will flow through the person and the neon lamp, which will cause a faint glow of the neon lamp, which will indicate the presence of a phase in the wire. The indicator is designed for voltages up to 500 volts. High voltage can damage the device (the resistor in it), then it will fail and it will become dangerous to use. Therefore, just in case, it is necessary to work with all safety measures: wear insulating shoes, the room must be dry. Because the electric shock in the event of a breakdown will be directed from the phase through the person checking to zero or ground, or any grounded metal (casing of a household appliance, heating battery, water pipe, etc.).

Such an indicator is also sensitive to voltages that occur in conductors where a phase is missing. It happens like this: in a socket, both contacts give off a neon indicator light. Phase is one of them. And the other is a “bad” zero. If a zero somewhere in the wiring is broken, broken or burned out, then there will be interference from the phase. Its voltage, of course, is not the same as in the phase, but it is sufficient for the indicator to show it with a neon glow. How then to distinguish zero and phase? In this case there is no success - nothing is determined. And we need to use other means. For example, try to find the phase with a multimeter.

It can be used as a single-pole one: press the tip of one pole to the contact where the phase is supposed to be, and grasp the second pole with your hand. But if there is a break at zero, it shows a glow on both contacts. In this case, you can check for a voltage drop between the two different contacts. Relative to the ground defined somewhere in another socket of a “good” zero. Two phase wires in different sockets, but in one phase they will show the absence of potential difference.

If there is voltage between the two poles, the neon indicator light should glow.

Using a probe - control lamp

A probe is made to determine the integrity of the wires. This is a light bulb with a battery and two fairly long wires with ends convenient for connection: pin or alligator clips. With such a probe it will be possible to then look for the break point in the neutral wire, which was mentioned above. However, such searches should already be done with the network completely de-energized.

But we need a probe to check for voltage. It is also called a control lamp - it is the same as a two-pole indicator, the difference is that instead of a neon light bulb, an ordinary incandescent lamp is used, designed for the voltage whose phase we are looking for. The advantage of this design is that the light bulb will light up only at its “native” voltage. However, if there is a possibility of sticking it into two different phases, it may burn out. But if there is no such probability (the apartment is powered by only one phase), then such a probe can be safely used. By plugging it with one pole into one contact of the socket, and connecting the other to the EXACT zero, we get light from the light bulb, indicating that we have found the phase. In this case, a torn zero will not produce any glow. Same as uncut.

How to determine phase and zero with a multimeter

To determine phase and zero, you can use a multimeter or tester. In this case, the voltage is simply determined. Everything is almost the same as in the previous case with the light bulb, only we will see the voltage value from the reading of the device. You just need to first set the AC (alternative current - alternating current) and the measurement range such that our mains voltage of 220 volts is within it, for example, switch the range “up to 500 volts”.

Polarity does not matter with alternating current; to determine the phase, you need to check the voltage between two conductors with two probes. It’s better to use a crocodile to cling to the “exact zero” (or the ground - the heating battery, just find a place where there is no paint - or rip it off), and use another probe to check the phase in the socket contacts. The phase should give how much? That's right, 220 volts, or less, as usual in our network. Zero voltage will give us a good zero - that is, it will show an unbroken zero bus, and some intermediate values ​​mean bad wiring. This is either a bad phase - there are bad contacts on the phase somewhere, and you need to urgently look for it - or a bad zero - broken. If both the zero and the phase in the socket are bad, this means that the wiring is completely unusable, and something is about to happen in the network.

And then a new stage begins - to find, find out, figure out all the faults and eliminate them.

Check functionality electrical network in an apartment or 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.

When performing installation work with sockets and light switches, it often becomes necessary to find phase and zero. Of course, for experienced electricians, such a task is a trifle, but for those who are little familiar with the rules of electrical networks, this question can lead to a dead end.

Indicator screwdriver. Nuances of use

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

Indicator screwdriver design

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 tip; it is needed to reduce the current strength to a value safe for the human body;
• next there is an LED, which connects to the contact patch located at the end of the screwdriver;
• the housing is made of transparent plastic, this allows you to see the LED light up.

Phase and zero in a screwdriver

Finding 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 get to the hand that touches it. metal plate. The current will pass through the body of the person who is performing this operation, and then go to the ground.

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

Application area

Any work that concerns electrical wiring must be safe. For this purpose, everyone should have this necessary tool in their home.

This device can be used for the following purposes:

• check which contact of the socket or switch the phase conductor is connected to;
• when the extension socket does not work, you can check all the sockets with a probe;
• with its help you can find out where the phase in the cartridge is connected: to the central contact or to the thread;
• find out whether 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 power supply is with alternating current, then there is no need to press your finger against the plate!

Screwdriver types

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

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

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

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

• a sound signal 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 direct current in household electrical appliances;
• determine the polarity of networks;
• with its help you can test the electrical circuit using light or sound indication.

Checking the device before use

Before use indicator device must be checked for serviceability. The battery located inside the device will help verify this. You will need to simultaneously touch the tip and another finger to the metal contact on the handle. The indicator light should light up at this moment.

If the device does not include a battery, then you will need a live conductor. You need to touch it with the tip of a screwdriver, and touch the metal on the handle with your finger. As a result, the LED will also light up.

Basic Safety Precautions

Be sure to follow the following precautions:

• It is prohibited to use a probe without a screw;
• Only the batteries can be removed from the device;
• after the battery is replaced, the screw should be tightened clockwise until it stops;
• if there are any on the sampler 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 on the network with the exact presence of the phase;

Important! When taking measurements electrical lines, the probe is held only by the isolated elements. The exception is voltage-free circuits.

Instructions for use

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

• ability to determine alternating voltage contact method up to 250 V;
• contactless up to 600 V;
• examining the circuit for continuity from 0 to 2 MΩ;
• polarity establishment: from 1.5 V to 36 V;
• the instrument must be stored in a dry place protected from moisture;
• It is better to carry out all operations with gloves to ensure a non-contact examination;
• After work, you should clean the tool from dust and debris.

Non-contact screwdrivers are very sensitive, it can react to both phase and neutral, although the real voltage will only be in one wire. Therefore, an ordinary electrician does not need such a screwdriver. 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 operation. If you accidentally touch the current-carrying part of the wire with a screwdriver 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 arise. These problems are not always worth calling in 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 a special tool, which is worth purchasing in advance.

The owner of an apartment or private house who decides to carry out any procedure related to electricity, be it installing an outlet or switch, hanging a chandelier or wall lamp, invariably faces the need to determine where the phase and neutral wires, as well as the grounding cable, are located at the work site. This is necessary in order to correctly connect the mounted element, as well as to avoid accidental electric shock. If you have certain experience working with electricity, then such a question will not confuse you, but for a beginner it can be a serious problem. In this article we will understand what phase and zero are in electrics, and we will 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 neutral conductor?

Purpose of the phase cable - supply electrical energy to the right place. If we talk about a three-phase electrical network, then there are three current-supply wires per single zero wire (neutral). This is due to the fact that the flow of electrons in a circuit of this type has a phase shift of 120 degrees, and the presence of one neutral cable in it is quite sufficient. The potential difference on the phase wire is 220V, while the zero wire, 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 to the generator phase. The purpose of the neutral wire (working zero) is to connect the zeros of the load and the generator. From the generator, the flow of electrons moves to the load along linear conductors, and its reverse movement occurs through neutral 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 chain with low rate resistance so that in the event of a short circuit the current is sufficient to immediately trigger the emergency shutdown device.

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

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

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

• Solidly grounded neutral cable.
• Insulated neutral wire.
• Effectively grounded neutral.

The first type of lines is increasingly used in the design 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 located under high voltage. The working zero, which is the fourth wire, is supplied from the same generator set.

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

What is a grounding cable for?

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

To the question - how to identify a grounding wire - one could answer: by the yellow-green sheath, but color marking, unfortunately, is often not observed. It also happens that an electrician who does not have sufficient experience confuses a phase cable with a neutral cable, 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 electrical wiring: finding zero and phase

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

About color coding phase, neutral and ground wires on video:

Checking with an electric lamp

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

Checking with an indicator screwdriver

A good assistant 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 indicator body. It consists of the following main elements:

• A metal tip shaped like a flathead screwdriver that is applied to wires for testing.
• A neon light bulb that lights up when current passes through it, thus signaling phase potential.
• A resistor to limit the amount of electrical current that protects the device from combustion under the influence of a powerful flow of electrons.
• A contact pad that allows you to create a circuit when you touch it.

Professional electricians use more expensive LED indicators with two built-in batteries in their work, but a simple device made in China It is quite accessible to anyone and should be available to 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 the work, since the glow of the signal lamp will be difficult to see.

When the screwdriver tip touches the phase contact, the indicator lights up. In this case, it should not light up either at the protective zero or at the grounding, otherwise we can conclude that there are problems in the connection diagram.

When using this indicator, be careful not to accidentally touch a live wire with your hand.

About determining the phase clearly in the video:

Checking with a multimeter

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

Conclusion

In this material, we answered in detail the question of what phase and zero are in modern electrics, what they are needed 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 grounding is very important. Incorrect test results can cause devices to burn out when connected, or, even worse, cause electric shock.

The main thing you should know: a regular digital multimeter does not have a separate mode for determining phase or zero; you can only find out by seeing the voltage value on the screen or not seeing it.

By and large, the principle of determining the phase with a tester is similar to the operation of a conventional indicator screwdriver, where the phase is determined by the glow of the built-in lamp, which lights up only if there is a phase - resistance - lamp - capacitance (person) circuit.

The current from phase flowing through such an indicator screwdriver passes through a high resistance built into the indicator, then also through the lamp in it, and then enters the container - which is a person (for this we touch the back side of the indicator screwdriver when determining ) and only if all participants in such a circuit are present, the lamp will light.

To determine the phase using a multimeter, set it to the AC voltage detection mode, which is most often indicated on the tester body as V~, at the same time, always choose a measurement limit - a setting higher than the expected network voltage, usually from 500 to 800 Volts. The probes are connected as standard: black into the “ connector COM", red into connector " V ΩmA ».

First of all, before looking for a phase with a multimeter, you need to check its performance, namely the operation of the voltmeter mode - determining the alternating current voltage. To do this, the easiest way is to try to determine the voltage in standard, household outlet 220v.

How to check the voltage in a 220V outlet with a multimeter

To measure the voltage in a socket with a digital tester, you need to insert the probes into the sockets of the sockets, the polarity is not important, the main thing is not to touch the conductive parts of the probes with your hands.

Let me remind you once again that the multimeter must be set to the AC voltage detection mode, the measurement limit is above 220V, in our case 500V, the probes are connected to the “COM” and “VΩ mA” connectors.

If the multimeter is working and there are no problems with connecting the outlet or power outages, then the device will show you a voltage close to 220-230V.

Such a simple test is enough for the tester to continue searching for the phase. Now, as an example, we will determine which of the two wires, for example, coming out of the ceiling for a chandelier, is phase.

If there were three wires - phase, neutral and ground, then it would be enough to measure the voltage on each of the pairs, in the same way as we determined it in the socket. In this case, there would be practically no voltage between the two wires - between zero and ground, respectively, the remaining third wire is phase. Below is visual diagram definitions.

If there are only two wires for connecting the lamp and you don’t know which one is which, then you won’t be able to identify them this way. Then the method of determining the phase with a multimeter, which I will now describe, comes to our aid.

Everything is quite simple, we just need to create conditions for electric current to flow through the tester and record it. To do this, we simply create an electrical circuit, according to the same principle as with an indicator screwdriver.

In the AC voltage testing mode, with the selected limit of 500V, we touch the red probe to the conductor being tested, and we hold the black probe with our fingers or touch it to a known grounded structure, for example, a heating radiator, a steel wall frame, etc. In this case, as you remember, the black probe is plugged into the COM connector of the multimeter, and the red one into VΩ mA.

If there is a phase on the wire being tested, the multimeter will show on the screen a voltage value quite close to 220 Volts; depending on the testing conditions, it may be different. If the wire is not phase, the value will be either zero or very low, up to several tens of volts.

Let me remind you once again, BEFORE STARTING THE TEST, BE SURE TO MAKE SURE THAT THE AC VOLTAGE DETECTION MODE IS SELECTED ON THE MULTIMETER, and not any other.

You will probably say that the method is quite risky, it becomes part of the electrical circuit and not everyone will want to voluntarily come under voltage. And although there is such a risk, it is minimal, because, as in the case of an indicator screwdriver, the voltage from the network passes through the large resistance of the resistor built into the multimeter and no electric shock occurs. And we checked the performance of this resistor by first measuring the voltage in the socket; if it had not been there, all the conditions would have been created for it, which, I assure you, you would have immediately detected.

Of course, as I wrote above, it is better to use grounded structures instead of a hand - radiators and heating pipes, the steel frame of a building, etc. but, unfortunately, such an opportunity is not always available and you often have to take the probe yourself. Experienced electricians advise in such cases to still take additional safety measures: stand on a rubber mat or in dielectric shoes, touch the probe briefly at first, right hand and only if no dangerous effects of current are detected, perform a measurement.

In any case, this is the only, most reliable and easiest way to determine the phase with a household multimeter yourself.

How to find zero with a multimeter

Zero, most often, is found with a multimeter relative to the phase wire, i.e. first, using the method described above, you find the phase, and then, having installed the red probe on it, touch the other conductors and when the tester on the screen shows 220V (+/- 10%), then you will understand that the second wire is zero working or zero protective ( grounding).

It is quite difficult to determine whether a wire is a neutral wire or a ground wire with one multimeter, because in essence, these conductors are one and the same and often simply duplicate each other. In certain grounding systems, neutral and ground are even connected to each other in the electrical panel and it is very difficult to accurately identify them.

The easiest way, in this case, is to disconnect the input wire from the grounding bus in the electrical panel; then, throughout the entire apartment or house, when checking the voltage between the phase and the grounding wires, you will not get 220V, as when checking zero and phase.

It is also worth noting the fact that if differential protection is installed in the electrical panel, when checking the ground wires relative to any other conductor, even zero.

If you know more reliable and universal methods determining phase and zero with a digital multimeter - be sure to write about this in the comments to the article, in addition, any opinions, experience, healthy criticism or question are welcome.

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