If two phases come into the sockets. How to install the socket correctly, and on which side should the phase in the socket be? Determining the phase with an indicator screwdriver

The most critical moment when installing a plug socket is connecting the wires to the contacts. At a minimum, you need to connect phase and zero to the terminals, and if modern wiring with grounding is laid, then there are 3 wires. The question often arises, which contacts to connect the wires to, which side is the phase, which is the zero. In everyday life, it does not really matter whether the phase in the socket is on the left or vice versa, zero on the left, but it is better to know their location.

Does the location of zero and phase matter?

Before figuring out how to find a phase in an outlet, you should understand why this is needed. Many people who are poorly familiar with electrical installation products believe that mixing up phase and zero when connecting an electrical appliance to the network is as dangerous as mixing up the polarity of batteries. In fact, the plug sockets used in Russia are non-polarized, and many plugs have a symmetrical design. So when you turn it on, there is one or the other pin on the left, and nothing bad happens.

Sometimes on forums and other Internet resources you can find statements that the quality of computer and audio equipment is reduced if the phase and neutral of the plug and socket are incorrectly combined. But this is a myth.

There are electrical appliances, when connecting which the location of the phase, neutral wires and grounding is fundamentally important, this is specified in the instructions. But their connection must be done by professionals, otherwise the device will be removed from warranty service. Such devices include gas boilers with an electric controller, but they do not have a plug that is plugged into an outlet, but are permanently connected to the network. If you are installing a socket for simple household electrical appliances at home, there is not much difference on which side to connect the phase wire and which neutral wire.

But professional electricians, when asked where the phase in the sockets should be, answer: on the right. This is an unwritten rule; PUE (electrical installation rules) do not regulate which side the neutral and phase contacts in a household outlet should be on. But it’s more convenient if everyone adheres to the same standard, so that the same electrician doesn’t have to guess whether the phase in the socket is on the left or on the opposite side. In countries where sockets are polarized, this principle is also observed. And if you want to do everything “according to science”, connect the phase wire to the right terminal, and the zero wire to the left, the question arises of how to determine the phase in the wiring.

Determination of phase and neutral wires

The easiest way to understand the purpose of the wires is to focus on the markings. In the Russian Federation and a number of European countries the following standard applies:

zero, or neutral (working zero) - a wire of blue, less often blue-white color
earth (grounding, protective zero) – yellow-green;
phase - any other color, often brown, black.

But color markings may be missing or may not correspond to the standard. In this case, use an indicator screwdriver (probe) or a tester.

Testing with a probe:

Hold the screwdriver body in your hand without touching the metal tip with your fingers.
Place your index finger on the end of the screwdriver where there is metal contact.
Touch the wires one by one; the LED indicator lights up when in contact with a phase wire.

If there are only 2 wires in front of you, and you have figured out where the phase is in the wiring, the problem is solved. If there are 3 of them, you need to distinguish the working zero from the protective zero, that is, grounding. To do this you will need a tester (multimeter). The phase wire is marked with a marker. On the multimeter, you need to select the AC measurement mode and set the measurement limit to greater than 250 V. One probe is pressed against the phase conductor, the second one touches the other two in turn. The display will show the voltage value. When measuring the voltage between phase and ground, this indicator is greater, between phase and neutral it is less.

Sometimes both measurements give the same result. In this case, you can check where the ground is by measuring the resistance. The stripped phase wire core must first be insulated. The device switches to resistance measurement mode; one probe is touched to an object that is precisely grounded, for example, a metal pipe, a heating radiator or a water tap. By touching the second probe alternately to two wires, measure the resistance. Between a grounded object and the ground wire, the resistance is within 4 ohms; when checking the neutral wire, it is higher.

If you don’t have an indicator screwdriver, a multimeter will help you figure out which wire is which in the wiring. Having selected the alternating current measurement mode, touch the grounded object with one probe and check the wires with the second. The device will show the following voltage values between the grounded pipe and the wires:

phase 150-220 V;
zero (neutral) – 5-10 V;
ground – 0 V.

Determining phase and zero in a socket

You can know exactly where the phase and neutral are in the socket if you installed it yourself, having first checked the wiring. But if you rent or bought an apartment on the secondary market, it is not known who installed the electrical installation products and whether he adhered to the “phase on the right” rule. In such a situation, how can you figure out where the zero and phase are in the socket? The same devices will come to the rescue. The indicator screwdriver is used in the same way as when checking wiring, only the tip is inserted alternately into both socket connectors.

When using a multimeter, you select the AC voltage measurement, one probe (any one) is inserted into the socket hole, the second one needs to touch your own body. If you hit a phase in the socket, the device will show more than a hundred volts, if you hit zero - only a few volts. There is no risk of electric shock unless you select the current measurement mode by mistake. Sometimes the indicator screwdriver shows that there are 2 phases in the socket, but judging by the multimeter readings, there is no voltage. This situation indicates a break in the neutral wire; when carrying out repair work, it is necessary to take into account that in fact there is voltage in the network.

There are also more exotic ways to determine the phase without special instruments. Instead of a multimeter, they use an incandescent lamp screwed into the socket, from which a two-core wire extends, one of the wires is attached to a pipe, a battery, and the second wire is checked. A lit light indicates the phase. In a similar way, the voltage between a grounded object and the wiring conductors is measured, using cut potatoes as an indicator. At the point of contact with the phase it darkens. Both methods are suitable for checking both wiring and an already installed outlet, but are quite dangerous - there is a high risk of electric shock.

Let's summarize. Determining zero and phase is fundamentally important when installing switches, but for household sockets it is not particularly important. You have to figure out the purpose of the wires during repairs, when the socket is dismantled and the ends of the wires are exposed. The phase wire must be insulated for the period of repair work, although for safety reasons you can wrap both wires with electrical tape. When installing an outlet, it is advisable to adhere to the unofficial, but generally accepted standard among electricians, and connect the phase to the right terminal. Color markings and an indicator screwdriver will help you distinguish zero from phase; if the wiring is three-wire, you will need a multimeter. You can check the contacts in the installed socket using both devices.

To understand what phase and zero are in a socket, an ordinary person (not a specialist) does not need to delve into the electrical jungle. As an example, let's take a regular plug socket that receives alternating current.

There are two electrical wires going to the outlet - neutral and phase. Current flows through only one of them - the phase phase (also called the working phase). The second wire is neutral (or zero phase).

Zero and phase in old sockets

To connect the old outlet, use two conductors. Some of them are blue (working neutral conductor). This wire carries current from the source of electricity to the household appliance. If you grasp the live wire but do not touch the other wire, you will not receive an electric shock.

The second wire in the socket is a phase wire. It comes in a variety of colors, including blue, green-yellow or light blue.

Note! Any voltage exceeding 50 volts is life-threatening.

Phase and neutral in a modern socket

Modern devices have three wires. The phase comes in any color. In addition to phase and neutral, there is one more wire (protective neutral). The color of this conductor is green or yellow.

Voltage is supplied through the phase. Zero is used for protective zeroing. The third wire is needed as additional protection - to draw in excess current during a short circuit. The current is redirected to the ground or in the opposite direction - to the source of electricity.

Note! It makes no practical difference whether phase and zero are located on the right or left. However, most often the phase is located on the left and the zero is on the right.

Determining phase and zero with a multimeter or screwdriver

Multimeter

The device is a combined electrical measuring device capable of performing several functions. The minimum configuration includes a voltmeter, ohmmeter and ammeter. Some modifications are made in the form of current clamps. Both analog and electronic meters are available.

To begin the measurement process, you must switch to AC voltage measurement mode. Measurement is carried out using one of several methods:

We clamp one of the existing probes with two fingers. We direct the second probe to the contact, which is located in the switch or socket. If the data on the monitor is insignificant (does not exceed 10 volts), we are talking about zero. If you touch another contact, the indicator will be higher - this is a phase.
If there are concerns about touching the dipstick, there is another way. We direct one of the rods into the socket. With the second rod we touch directly to the wall next to the outlet. The result will be approximately the same as in the case described above.
There is a third way to measure using a multimeter. We touch the probe to a grounded surface (for example, the equipment body). We touch the surface to be measured with the second probe. If the wire is a phase, the multitester will detect a voltage of 220 volts.

The indicator is a simple way to determine the phase, accessible even to a person who is doing this for the first time. The test screwdriver looks like a standard one. The difference is the presence internal device at the indicator screwdriver. The screwdriver handle is made of special transparent plastic. There is a diode inside. The upper part is made of metal.

Note! The indicator screwdriver must not be used for purposes other than its intended purpose. It is not intended for loosening or tightening screws. Improper use of the test screwdriver will cause its failure.

To find phase and zero using a screwdriver, you need to perform the following sequence of operations:

Use the end of a screwdriver to touch the contact.
Press the metal button at the top of the screwdriver with your finger.
If the LED lights up, we are talking about a phase. If it doesn't react, it's zero.

Note! An indicator lamp rated for 220-380 volts will glow at voltages greater than 50 volts.

Do not touch the bottom end of the screwdriver while taking measurements.
Keep the screwdriver clean, otherwise there is a high risk of insulation damage.
If you need to determine the absence of voltage, first check the functionality of the device, which is definitely under voltage.

Advice! In a DC network, the polarity of the contacts is determined very in a simple way. To do this, simply immerse the wires in a container of water. Bubbles will begin to form near one of the wires - this is a minus. The second wire is positive.

An indicator screwdriver should not be confused with a dialing device. The dialing screwdriver is equipped with batteries. When working with such a device, you do not need to press the button to determine zero and phase, since the screwdriver will light up in any possible situation.

In our rapidly developing information age, we have to keep abreast of all events, and the desire to learn more and apply knowledge in practice is increasing more and more. Even if the light suddenly goes out in the apartment or the outlet doesn’t work, we try to find the reasons ourselves and find a solution to why this is happening. It must be remembered that when working with electricity, it is important to follow safety precautions, do only what you are absolutely sure of and remember that if you handle electricity carelessly, you can feel the current and 220V voltage surge, which can lead to dire consequences.

The socket in the apartment does not work: what to do?

There is one fault in electrical wiring that confuses novice electricians. Although, at first glance, everything is in order: the machines are turned on, the wiring is intact, but the electrical appliances have stopped working, and the indicator on the screwdriver is on, thereby indicating the presence of two phases on both wires. This also indicates that the zero is missing. This phenomenon is not uncommon, but it will leave an inexperienced electrician scratching his head.

If your socket stops working, then an indicator screwdriver will help you check for the absence of a zero and the presence of another phase in the socket.

This situation has several consequences: all devices will remain working, or the equipment and lamps will simply burn out. The thing is that there are phases of the same name, and there are different phases. A common household appliance called a tester will help us figure out the type of phase in an outlet. It can be used to check various electrical parameters. To do this, you need to connect the device to an outlet and measure the voltage between two phases. If voltage is present, the phases are of the same name, and if it is absent, then the phase is of the same name.

Why there are two phases in the socket: a simple explanation

To get the answer to this question, it’s worth understanding a little about how electricity comes to our apartments. From the main electrical main to the substation of high-rise buildings there are four wires: zero and three phases - this is a three-phase network with a voltage of 380 volts. The phases are then separated to different sides of the courtyard. Each entrance switchboard receives one phase and one more neutral wire. This single-phase network and its voltage is 220 Volts. There are 2 wires coming from the access distribution board to the apartments (in new buildings, another wire is added - grounding).

Only one phase is supplied to the apartment through the electric meter and the circuit breaker panel.

Let's consider a situation where we wanted to hang a shelf in a room on the wall, connected a drill and started drilling the wall. Suddenly the machine on the dashboard goes off, the lights in the apartment go out and the drill stops working. However, using an indicator screwdriver, we established that there are two phases in the socket. Most likely, when drilling, we touched the wiring with the drill, and thus we managed to short-circuit 2 wires, which caused a short circuit and the circuit breaker tripped. Thus, we got the phase of the same name in our apartment. To eliminate this malfunction, it is necessary to de-energize the apartment, inspect the place where the drilling was carried out and connect the broken wire. In private sectors, where power lines are located on poles, it is possible that one of the phases shorts to the neutral wire when they come into contact. In this case, two opposite phases may appear in houses and this can lead to failure of household appliances.

There are two phases in the socket: what to do?

The presence of a phase on the neutral wire is due to the fact that the phase is under constant load: a refrigerator, light bulb or other electrical appliance. Electrical wiring in houses and apartments is designed in such a way that all wires are connected to the zero bus in the electrical panel. To make sure of this, just turn off all electrical appliances. So, all your devices are turned off, but a phase still appears on the neutral wire.

Universal solution methods:

Turn off all electricity in the apartment;
Check that each switch is set to the “off” position;
Unplug all household appliances from the outlets, no matter how many you have;
Visually diagnose a malfunction on the panel or at the work site;
Call qualified electricians.

In any case, to reliably diagnose the true cause and eliminate the malfunction, you need to resort to qualified help.

Two phases in the socket: reasons and solution

There are a number of most likely reasons for the occurrence of two phases in an outlet - from the banal burnout of a safety plug or the shutdown of a circuit breaker on the electrical panel, to the shorting of wires and the appearance of induced currents.

The most common reasons for the occurrence of two phases:

Strong winds or tree branches have shorted the wires;
A short circuit in which the braid of the wires melts and they close;
Zero is closed to phase, for example, when drilling;
Induced current – due to the presence of nearby high-voltage power lines;
Overvoltage - an increase (up to 380 Volts) or a decrease (up to 40 Volts) in voltage values;
The neutral wire burned out in the internal electrical wiring system.

When troubleshooting, you need to carefully analyze and consider all possible cases.

Reasons for appearance: two phases in the socket (video)

Remember, electricity punishes incompetence. If you don't know what to do or have any concerns about faulty wiring or appliances, call a professional immediately. This will help avoid unwanted consequences in more than half of cases, and can help save life and property.

Electrical wiring is done according to simple principles, which are studied in school, but some faults often go beyond standard ideas about the operation of the electrical network. Two phases in an outlet is a common problem that regularly confuses users with insufficient experience in electrical wiring repairs.

Where and why the second phase may appear

Here we must immediately make a reservation that since only one phase wire enters the apartment, the concept of “second phase” implies that the voltage indicator shows the phase in the contacts on which it should initially be at zero. The second phase, in the correct understanding of these words, cannot exist in an apartment.

The next point that you need to know to understand the essence of the problem is that every electrical appliance is a conductor of electricity. The simplest example is a light bulb - its filament glows due to the fact that it is a conductor of electric current. Essentially, the light bulb shines because it closes phase and zero between each other, and short circuit does not occur because the filament has a certain electrical resistance. Other devices work in the same way - they are often connected to the network through transformers, the windings of which are made of copper wire. Again, a short circuit does not occur, since due to the length of the wire and its cross-section, it has electrical resistance, but in essence, when a plug of any device is inserted into a socket, the phase and zero are closed in it.

Now it should be clear why there are two phases in the socket - this malfunction can only appear if zero is missing. The phase comes to the socket, passes through the electrical appliance connected to it and appears on the neutral wire, and from it on those sockets that are located after the zero break. Accordingly, if you turn off all the switches and remove all the plugs from the sockets, the indicator will show the phase on only one contact.

As a result, a phase instead of a zero may appear in one separate socket (provided that it is double or triple and a plug of some electrical appliance is inserted into one of the plugs). Further, 2 phases can be in one of the rooms, in half of the apartment, or generally everywhere.

You also cannot discount the possibility of a short circuit, for example, when drilling a wall or poor-quality laying of wires in a junction box. With some luck, you can hook the wiring in such a way that the neutral wire is cut off from the main network and stuck to the phase wire. In this case, the indicator will show two phases in the outlet even when electrical appliances are disconnected from the network.

In this video you can see how this malfunction is reproduced on a specially assembled stand:

Two phases in one socket

Such a case practically never occurs - it is a rare exception that confirms the rule. If this happens - all the other sockets work flawlessly, there is light everywhere, and in one single socket the indicator shows two phases, then first of all the socket itself is disassembled. The breakdown will most likely be in another place, but first, just in case, you need to make sure that it is not in the place that is easiest to get to.

If you're lucky, a broken, burnt-out, or jumping-out wire will be found in the socket box.

When the outlet is working properly and without any signs of overheating of the wires, the next step is to determine how it is connected - directly to the junction box or through another outlet. In the second case, there is a possibility that the neutral wire was poorly screwed into the “parent” socket and has now fallen out.

Next, the junction box is checked - this is the most likely place where a bad connection can be found. Here we must take into account that the phase wire is not so demanding on the quality of the twist - if the connection is bad, it heats up, but still works for some time. The neutral wire can oxidize without any visible consequences - to see this you will have to unwind the twists, strip the wires again and put everything back together.

If the twisting is in order, then all that remains is to ring the wire with a tester - if it shows a break inside the wall, then for repairs you will have to break the groove.

When an outlet stops working in a house where the wiring has been done recently and according to all the rules, then it is additionally worth checking whether it is a power outlet to which a water heater or similar powerful device is connected. In this case, the reasons must be sought in the main distribution panel, from where it can be powered, bypassing the distribution boxes.

Two phases in several sockets

The situation is similar to the previous one, but now in several outlets at once, often located in the same room. In this case, the lighting may or may not work, depending on the method of its connection.

There is no point in checking the sockets here, with one exception - if they are all connected by a so-called cable. In this case, the wires from the junction box come to one of them, and the rest are connected in series. The PUE strongly does not recommend doing this, but anything can happen.

The procedure for troubleshooting depends on the desire to climb into the junction box and whether there is a possibility of a daisy chain connection. Most likely, a broken wire will be found in the distribution box, but if all the connections there are normal, then you need to disassemble all the sockets in the room one by one.

Two phases in half the rooms

This happens if the distribution boxes are connected in series one after the other. What to do in this case - the solution is standard - you need to sequentially go through all the boxes in search of bad contact.

The whole difficulty is that often there is no connection diagram, so it is not known from which room and into which of them the wiring is laid. You should also take into account the option that the contact can burn out both in a room in which the sockets do not work, and in the previous one according to the diagram, where the indicator shows normal voltage in the sockets.

There is a solution so as not to disassemble the terminal boxes in all rooms - you can change the phase and zero on the input panel, and then use a voltage indicator that can show the phase through the wall. Before doing this, you need to make sure that there is no grounding anywhere in the sockets and, just in case, disconnect the grounding, if one is connected.

Two phases in all sockets

If the lights in the entire house are turned off, and the voltage indicator shows two phases in the sockets, the problem is most likely on the input panel.

In this case, you must also check the ground wires in case they are grounded. At the same time, until you are sure that there is no voltage on them, you should not touch the grounding contacts with your bare hands and prohibit children from touching sockets and electrical appliances.

Older houses often have plugs or circuit breakers not only on the phase, as recommended by the latest editions of the PUE, but also on the neutral wire. The burnout of such a plug is equivalent to a break in the zero, so it is recommended to check them first.

It is also necessary to take into account the possibility of the absence of an electrical panel as such, when the wire from the meter goes directly to the main distribution box - the faulty contact may be in it.

In the normal state of the electrical wiring in the outlet, one contact has 220 Volts, and the second is not energized. This is ideal... Sometimes the indicator can show two phases in the socket at the same time.

To a novice electrician or amateur, such a situation may seem absurd, but it is reality. In some violations, this is exactly the picture observed.

Single-phase current of 230 volts is supplied to residential buildings. According to this diagram, it turns out that two phases cannot appear in the socket. In older buildings, the wiring is made of two-core cables. Along one line (phase) the current goes to the consumer, and along the other (zero) it returns.

With such a circuit, the reasons for the appearance of two phases in the plug connector may be different. New houses have grounding, which can cause accidents only if there is unqualified intervention in the electrical circuit of the home.

Break of zero at the input

If the zero wire in the incoming cable is disconnected, the lights in the apartment will go out and electrical appliances will stop. Checking with an indicator will show the presence of a phase on each contact of the socket. The classic question arises: “Who is to blame and what to do?”

In the absence of zero, the current searches for a free line. If the lamp is turned on, it does not light, but the phase passes through the filament to the neutral wire, then to the bus, and from there to the neutral line of sockets. The phase can also come from a device connected to any plug connector in the apartment.
Now there is a phase on each socket of the socket. The indicator emits a light signal when each contact is touched.

A multimeter helps to easily clarify the situation. If you measure the voltage difference between two phases, the device will show a zero value. It is clear that this is the same phase. It is enough to turn off the lamps and disconnect the devices from the sockets and the second phase in the socket will disappear, because the voltage and neutral supply lines do not have other connection points.

It is necessary to restore the incoming zero line. It is possible that the wire has simply become disconnected from the bus. This problem can be dealt with even at home. De-energize the apartment by opening the phase input and check the absence of voltage. Insert the neutral lead into the terminal and tighten the screw.

Breakage of the neutral wire in the junction box or in the wall

Sometimes a zero break occurs in the junction box. In this case, part of the apartment's wiring is functioning normally, but the line connected to this box is inoperative. It is enough to find where the zero broke off or burned out and restore the connection.

It happens that two phases appear in the plug connector due to damage to the neutral wire inside the wall. The cause of the malfunction is negligence when drilling holes. If you break the insulation by breaking through the wire, the neutral conductor will be welded to the phase conductor. In this case, there will also be two phases in the outlet. It is necessary to lay a new line or open the damaged area and repair the wiring.

Automatic protection on the zero line

In old houses protective devices installed both on phase and zero (nowadays such a connection scheme is prohibited). If an overload occurs, it is possible that the circuit breaker will operate only on the zero line. The consequences are the same as if the zero broke off or burned off.

Induced currents

Everything works fine, but the indicator detects voltage on each pin of the plug connector. Moreover: the device shows two phases in the socket when the power supply to the entire apartment is turned off. This completely unrealistic situation can happen if a high-voltage power line runs near your home.

This is the so-called pickup or, to put it more correctly, induced voltage. Even experienced electricians can get confused here. Work in this case is associated with a high risk of electric shock, so only professionals should perform it.