How to determine the neutral wire. Indicator screwdriver: types, device and methods of use

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

If it is necessary to service apartment electricians, in particular, to replace sockets, light switches, or carry out minor repair work, it becomes necessary to determine the phase and zero. If a person has some knowledge of the basics of electrical engineering, then it will not be difficult for him to find the phase and zero. But what if you don't have these skills? The search for phase and zero is not the same difficult process as it may seem. Consider several ways to determine the phase and zero.

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

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

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

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

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

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

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

If the light bulb indicator screwdriver caught fire, then this wire is phase, that is, phase. The other wire, respectively, is zero.

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

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

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

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

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

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

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

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

There are often cases when it is necessary to determine which wire is “phase” and which is “zero”, especially if the wiring is old or there are doubts about the competence of the builders. There are several ways, but the most preferred method is using an indicator screwdriver.

If the wiring in the house was done by specialists, and the house is fairly new, then it is not difficult to determine which wire is the phase and which is zero. The wires are different colors. If the wiring is done professionally, then the phase wire is brown (sometimes black), and the neutral wire is blue (light blue). In new houses there is also a third, protective, so-called "land". It is striped (yellow-green) or yellow. It is usually used when connecting powerful electrical appliances (washing machine, air conditioner, etc.).

How to determine zero and phase - buy an indicator screwdriver

To determine the phase, we need one simple device - an indicator screwdriver. There are many varieties of them, but you should not choose an expensive one with many functions. It is quite simple, but it is better to buy it in specialized stores. Make sure it is rated for at least 500 volts. This is usually indicated on the handle or packaging. The tip of the screwdriver should almost completely be covered with plastic.

How to determine the phase

We insert the tip of the screwdriver alternately into the holes of the socket and touch the end part (“penny”) of the screwdriver with your finger. In no case do not touch the bare part of the screwdriver's sting. If the LED inside the screwdriver lights up, this is the phase. We check the second hole - if the LED does not light up, then this is zero.

There are other more difficult ways phase detection, but searching for a phase with an indicator screwdriver is a simple, inexpensive and, most importantly, safe process.

For more information about indicator screwdrivers, see the video:

In old houses, two-terminal sockets are still preserved. In this case, you can simply check the device using a phase tester. You need to take a tester (indicator screwdriver), insert it into any socket of the outlet. Put your finger on the metal cap on the handle. When the neon light comes on, it will indicate "phase". The second terminal must be zero. But that doesn't always happen.

Coloring, indicator screwdriver or multimeter

The easiest way to check grounding is to look at the color of the insulation.

At the ground wire, it should be yellow with green stripes, and at zero light blue. But this requirement is not always met.

In some old houses, the electrical wiring is made by separate conductors. If the owner had to make changes in the junction box, then it is quite possible that only two phase or neutral conductors come to the outlet. Therefore, both sockets must be checked. When zero is touched, the neon light on the voltage indicator should not light up.

IN modern buildings three-terminal sockets are used. Phase, zero and ground conductors come to it. Contacts must match your functional purpose. Otherwise, accidents may occur when using washing machine or boiler. Therefore, questions arise on how to check the grounding in the outlet in order to avoid installation errors and calmly, without fear, use your appliances.

The indicator screwdriver is guaranteed to determine only the phase. It cannot distinguish zero from earth. A small pickup is not enough to light up a neon light bulb. Then we find the phase and zero with a multimeter or voltmeter.

Multimeter reading options

Any device, indicator screwdriver or tester, must be checked for operability and only then used. The insulation must be intact, without cracks or breaks. The tip of the probe must be separated from the holder by a dielectric washer to protect against accidental contact. Frame measuring device must be whole. Before measurement, the plugs are inserted into the sockets of the device, which correspond to the measurement of alternating voltage. After making sure that the device is working, you need to transfer it to the mode of measuring alternating voltage with a scale of 750 V. This is necessary in case of measurement line voltage when by mistake two phases were brought to the outlet.

This method of testing the outlet is suitable if the inspector is sure that the ground contact is really ground. Then the task is to find zero. One probe touches the grounding contact, and the second is inserted into any outlet socket. There may be the following options:

• the device shows 220 V, which means the contact is phase;
• if 0 or units of volts, then this is the neutral wire.

If the multimeter shows 0 volts relative to the ground one on the socket contacts, then they are all connected to each other somewhere.

Readings of a few volts say it's zero. But how to determine zero when the house is supplied with electricity through the TN - C power supply system and re-grounding next to the building? Indeed, in this case, there will be zero readings of the device.

To make sure that this conductor is zero, you need to turn off the grounding in the access electrical panel. Then measure the voltage between the socket contacts of the socket. The device shows 220 V - the socket zero is found. The multimeter shows nothing - grounding is found.

When the device reads 220 V on each contact relative to the ground, an additional measurement must be made between the two sockets of the socket. The device shows 0, which means that one phase is connected to both sockets. Otherwise, the device will show 380 V, which means the presence of two phases on the outlet.

Determining the purpose of conductors

When working with electrical wiring, it is imperative to double-check the purpose of the socket conductors. There is no guarantee that the electrician or the previous owner of the premises did not mix up the wires. Therefore, if the tester shows a voltage of 220 V relative to the terminal on appearance being grounding, this does not mean that it is such. This means that one of the contacts is a phase, and the second is zero or ground. If the tester shows 0, then there is a neutral and ground conductor. It is impossible to understand exactly what is what.

In the absence of absolute certainty in the purpose of the grounding terminal, the sockets act differently. First you need to exclude the presence of two phases. We check the voltage between all contacts. If the 380 V device does not show anywhere, but only 220, then one phase conductor is connected to the outlet. Now you need to start looking for grounding.

First you need to disconnect the grounding conductor in the floor panel. It is connected through bolted connection to a special busbar welded to the body of the electrical panel.

After that, the voltage between the female connectors is measured.

If the device shows 220 V, then the socket contacts are the phase and neutral wires, and the ground terminal is indeed one. Now knowing exactly where the ground is, you can determine the remaining connectors, but first you need to reconnect the "ground" to the ground bus.

We measure the voltage relative to the ground terminal. One socket shows 220 V - this is a phase, the second - 0, then this is a zero contact.

If the multimeter reads 0, then the ground was connected to one of the socket contacts, and the second one is zero or phase. Now we carry out measurements between the socket and ground contact of the socket. If there is no voltage, then this socket is the real ground.
The readings at 220 V speak for themselves.

Wiring check

Checking the grounding of electrical wiring is about the same as with a socket. To measure network parameters, you will need a three-phase or single-phase multimeter, as well as an indicator screwdriver.

When repairing electrical wiring and connecting a washing machine, electric heater, stove, oven and other appliances, it is necessary to change cables and connections in junction boxes. In this case, you need to find out the purpose of each conductor, you need to check the presence of grounding in the right places.

First you need to turn off the input machine on the floor board. Then open the junction box. Separate the wires in different directions so that they do not touch each other, and remove the insulation at the junctions.

After that, the input machine turns on. The indicator screwdriver is the phase wires. They can belong to one, two or three phases.

If you have a three-phase multimeter, you can immediately check the network status. With a single-phase multimeter, determining the number of phases takes longer. For example, if the voltages between three wires are 0 volts each, then these are phase wires from one phase. If the device shows a voltage between two wires of 380 V, and between the other two 0, then two phases. At a voltage of 380 V between all conductors, we can talk about the presence of three phases.

The definition of grounding occurs, as in the case of a socket, only there will be more wires here. First, the ground wire in the floor panel is disconnected. Then one probe of the multimeter clings to the phase wire, and the second to the conductor of an unknown purpose. If the device shows a voltage of 220 V - this wire is zero, if zero, then this is the ground.

Then turn off the input machine. The ground wire is connected. When the check is completed, the correct connection all elements of the electrical network, the connections are isolated, the box is closed. The circuit breaker is turned on.

« phase"From "zero" will not be a big deal. phase wire should be black-brown, "zero" blue, and the ground wire yellow-green. As a rule, with single-color wiring, the ends of the wires are equipped with special insulating tubes - cambric, which have the appropriate color.

See how 2 other wires are connected in the electrical panel. Usually, in access electrical panels, zero and ground are 2 wires of the same name connected to the metal case of the electrical panel. Such a zero and ground connection is used when connecting to transformer substation With dead-earthed neutral. If 2 wires that are not energized are connected at one point to zero and both are of the same section, then any of these wires can be zero.

In the case of connecting the building's wiring via 5 wires with a separate ground and zero connection, the neutral wire connection point will be located on an isolated bus, where the power zero is connected. In this case, the ground wire is connected to metal case electrical panel. If the wires are different colors, then finding out what this or that wire is connected to is not very difficult. To do this, draw a wiring diagram in the electrical panel and connect the power outlet according to this diagram.

Disconnect neutral and ground. Locate the disconnected ends of the wires so that they cannot get on the case or short out with other wires in the electrical panel.

From the side of the outlet, connect any of the 2 wires to the phase, then turn on the machine in the electrical panel and use the phase indicator to find the wire to which you have applied power.

When performing repair and construction work milestone is the connection of premises and buildings to the power supply system. In this case, in addition to electrical wiring, a large number of other equipment, including sockets and switches. When making connections, the question often arises of how to determine the phase and zero, as well as the ground conductor in the electrical network. There is no difficulty in solving this problem.

However, simple owners of apartments and private houses without special knowledge and experience often cannot solve this problem on their own. It is possible to determine the purpose of each conductor using several simple and affordable methods.

How to determine the phase and zero with an indicator screwdriver

The simplest and most common way to accurately determine the phase and zero is to use an indicator screwdriver. This operation does not present any difficulties and requires only compliance with a certain algorithm of actions.

When solving the question of how to determine where the phase is and where it is zero, first of all it is necessary to de-energize the line and turn off the machine through which the home electrical network is powered. After disconnecting, strip the wires to be tested, removing about 1-2 cm of insulation. Next, the conductors are separated from each other by safe distance. This must be done to exclude the possibility of a short circuit in case of accidental contact after applying voltage. After all the preparatory measures, you can begin to determine the phase and zero. First, turn on the machine and apply voltage to the network.

Direct check of the phase and zero by the tester is carried out as follows. The indicator is clamped between the thumb and middle finger. At the same time, do not touch the exposed, non-insulated part of the screwdriver tip with your fingers to avoid impact. electric shock.

The index finger should touch the round metal protrusion located at the end of the handle. After that, the tip of the screwdriver is applied to the stripped ends of the conductors. If the tester has touched a phase conductor, the LED lights up in this case. Therefore, the second wire is zero. The neutral wire is determined when the indicator light did not light up initially.

How to determine phase and zero with a multimeter

In addition to an indicator screwdriver, phase and zero determination can be performed using a multimeter. In this case, it is also necessary to strip the conductors to be tested. Must be de-energized first electrical network by turning off the machine. Thus, it is excluded in case of accidental contact of the conductors of the phase and zero. The wires themselves need to be moved apart a little. After that, the machine should be turned on again.

Next, the limit value for measuring alternating voltage is set on the multimeter, which is more than 220 V. Then you need to look at what markings the sockets with the probes of the device have. The probe in the COM socket is not suitable for determining the phase, therefore, the remaining probe, marked with the symbol V, will be used. Having decided on the probes, you can begin to determine the purpose of the wires.

You need to take the probe, touch it to one of the wires in the outlet and look at the readings of the multimeter. When displaying data with a small voltage value (less than 20 V), the wire will be considered as a phase wire. If measuring device shows a zero value, then the wire itself, respectively, will be zero.

For measurements, any type of multimeter can be used - with a digital display or pointer. The accuracy of measurements with a multimeter is much higher than with an indicator screwdriver. When determining the phase and zero with a multimeter, it is forbidden to touch the phase and ground wires at the same time. Such actions may cause short circuit and traumatic burns.

How to determine the phase and zero without instruments

Quite often, situations arise when there is no indicator screwdriver and a multimeter, and you need to find out the purpose of the wires so as not to stop electric installation work. In such cases, you have to solve the problem, determining the phase and zero without a device.

Most in a simple way it is considered to determine the purpose of the wires by their. This technique brings positive result only when the wiring has been completed in compliance with all technical rules. In this case, the color of the insulation directly indicates the ownership of a particular wire.

The ground wire is painted yellow-green, and the neutral conductor is most often blue or of blue color. For the phase conductor, a black, white or brown wire is selected. The correctness of the connection can be checked visually, not only in the shield, but also in junction boxes, at the chandelier and other points.

The second way to determine the phase and zero involves the use of the so-called control light. You can use an ordinary incandescent lamp and two pieces of wire, 50 cm long each. The cores of the wires are connected to the light bulb through and the design is ready for work. One end of the wire needs to touch the heating pipe, and the other end - the wires to be checked. If the light turns on when touched, then this wire is phase.

This method at home is considered dangerous due to the high probability of electric shock. It cannot be used when the voltage limit is present in the network. It is safer to use neon bulbs, which allow you to determine the purpose of the wires with no less accuracy.