During normal operation of the outlet, checking the presence of voltage, the picture should look like this. When you touch a phase wire, a light warning should appear, and when you touch a neutral wire, the indicator light should not light up.
But if the socket does not work and the indicator shows on the wires there are two phases in the socket, what to do and how can this happen?
This phenomenon occurs quite often, usually in houses with old or poorly executed electrical wiring. Where do these come from? two phases in the socket, let's figure it out possible reasons their appearance:
The neutral wire in the internal system has burned out electrical wiring
This is the most common reason. In the absence of a null connection the phase through the filament of light bulbs in a chandelier, or through electrical appliances connected to other sockets by induced current will also be present on the neutral wire. In this case, the socket containing two phases does not work. This cause can be correctly diagnosed by turning off the electrical appliances plugged into them from all sockets by disconnecting the plugs from the sockets. Next, you need to turn all switches to the off position. If you don’t know in which position the switch is on and in which it is off, you can simply unscrew the light bulbs from the chandeliers and lamps, the effect will be the same. After you have completed all the steps indicated above, you need to check the voltage in the outlet again. You should get the following:there must be a phase in the phase wire, accordingly the indicator gives a light warning, and when you touch the neutral wire, the indicator light should not light up.In this case, you should start looking for the cause of the malfunction:
- in places where paintings and photographs were recently hung on the wall. As a rule, in 95% of cases, such home tuning ends with a broken wire. In this case, you need to turn off the power supply to the apartment (turn off plugs, circuit breakers, package switches) and make sure there is no voltage. Next, remove the layer of plaster and release the wire, visually diagnose the location of the damage and eliminate the fault by connecting the wires and insulating them. After all the work has been completed, turn on the power supply and check the functionality of the outlet. After this, the damaged area can be covered with plaster or gypsum mortar.
- if there is no work to update the design of the housing before two phases appeared in the socket was not carried out, then a possible malfunction may be in the junction box. In this case, you should start your search with distribution boxes, which are located in the room where the outlet is located. We turn off the power supply to the apartment, remove the cover of the distribution box, look for burnt, melted or fallen off wires. If there is no fault in this junction box, open the nearest one. Once you have visually diagnosed the problem, we proceed to fix it. We make a new connection, isolate it, close the cover of the distribution box, turn on the power supply and check the functionality of the outlet.
- in the electrical panel. If you have access to the power panel, you can open it and visually view all the contacts and connections. If you find melted wires, burnt contacts, or wires that have fallen off the connection points, you must immediately contact the organization servicing this electrical panel to troubleshoot the problem. Produce do-it-yourself repair without relieving tension, it is DANGEROUS TO LIFE.
Overvoltage has occurred
- Overvoltage is an increase or decrease in voltage values from normal (220-230 volts) to high (360-380 volts) or vice versa low (40-80 volts). When an overvoltage occurs, the light may blink at first, then the light bulbs begin to burn very brightly or very dimly.
The main danger is when the voltage increases (360-380 volts). Light bulbs begin to glow strongly, in some cases even hum, and household electronics begin to smoke. React instantly to increased voltage: computers, microwaves, Digital Watch, televisions, audio and video equipment. They burn out or start to work incorrectly.
At low voltage values (40-80 volts), such significant damage to household appliances is not caused; due to the low voltage, it simply does not turn on, and the lighting barely glows, so that you can see the barely smoldering filament in the light bulb. The reason is very commonplace: somewhere along the electrical wiring line from the substation to your meter, the neutral wire was damaged.
What happens during overexertion? Modern electrical networks use four-wire cable lines. Three wires are used to transmit three independent phases, and the fourth for zero. When the neutral wire is damaged, the current, like water, instantly fills the free niche and rushes to where the smallest load is, as a result, it turns out that two phases arrive along the phase wire and along the neutral wire instead of the required 220 volts, so it turns out 380. Accordingly, since the current has escaped into the free niche with a small load, then where it escaped from there remains a small voltage (40-80 volts) or nothing at all.
What to do?
- Need to quickly turn off the power supply to the apartment
- unplug everything Appliances
- turn all switches to the off position.
- Call electrical service personnel. Wait until the team of electricians eliminates the causes of the overvoltage, then they take control measurements of the voltage, draw up a report, and only after that can the power supply to your apartment be restored again.
Induced current
The socket operates in normal mode, but when measuring, the indicator diagnoses two phases. This phenomenon often occurs if there is a high-voltage power line near your home.
This is one of the most dangerous cases, since the induced voltage will be diagnosed by the indicator even when the voltage supply to the apartment is completely turned off, which can mislead even a professional in this matter. In this case, a voltmeter or multimeter will help; it will accurately show the presence or absence of voltage.
Triangle.
To transfer electricity between settlements voltage electrical network increases many times over. This is done to reduce the current load of the network; in other words, as the voltage increases, the current strength in the power lines decreases.
For example, if, when arriving at the ASU of residential buildings, the linear voltage of the network (between phases) is 380 Volts, then at high voltage lines power transmission voltage can increase from 6,000 to 1,150,000 volts.
The reduction to 380 Volts occurs inside transformer substations where a step-down current transformer is installed.
In electrical engineering, there are two schemes for connecting the windings of step-down transformers: “star” and “delta”. In most cases, in modern electrical networks for domestic needs, a “star” circuit is used, everything is standard here, there are 3 phases and zero (solidly grounded neutral). Line voltage = 380 Volts (voltage between phases), and phase voltage = 220-240 Volts (between phase and zero, ground).
As a rule, the ASU receives a four-core cable through which a voltage of 380 Volts is supplied, then it is divided into separate “zero + phase” lines, which come to the apartment. As a result, at the outlet we get a network voltage of 220-240 Volts.
But in the “triangle” there is no zero, there are only three phases and that’s it. The ASU comes with a three-core cable, through which a voltage of 380 Volts is supplied.
Since in a triangle circuit the phase voltage = linear, it is then divided into separate lines “phase + phase” and it is in this form that the voltage comes to residential apartments. That is, in such a network there will be two phases on both contacts of the socket, while household electrical appliances will function properly under normal operating conditions. The outlet will have a voltage of 380 Volts.
It is worth noting that the triangle pattern in modern networks is becoming less and less common, in most cases in areas of cities and villages with old housing stock.
Electrical wiring - pretty a complex system With important features and nuances. It happens that serious breakdowns occur in it. Two phases in the socket - clear example. Let's consider what a malfunction is, for what reasons it occurs, and how it is eliminated.
general information
The appearance of two phases is determined using special devices- voltage indicators and voltmeters.
In most apartments/houses the wiring is hidden. As practice has shown, it is more vulnerable than the established open method. The latter will not be pierced by accident if it is necessary to hang a picture or a carpet. Co hidden wiring more difficult. It is difficult to determine its location, because builders usually do not leave diagrams, and the equipment for such work is expensive.
Damage varies. Often an apartment/house or some separate room is left without electricity. In cases where circuit breakers are installed that quickly eliminate short circuits, this is not noticeable.
While such damage can be prevented, there is no protection against damage to the junction box. There are several reasons for their appearance:
- The work on connecting the wires was done poorly.
- The junction has oxidized and collapsed.
- A connection has occurred between aluminum and copper wires. When exposed to moisture, the wires oxidize, resulting in breakage.
Such faults are easily detected by the smell of burnt insulation.
Break of neutral conductor
If there is a zero break, electrical appliances connected to the outlet will not work. Perhaps the voltage will disappear in other sockets.
If the breakdown occurred for this reason, then the solution is quite simple. It is enough to turn off the equipment from the network. What to do next:
- Identify outlets without voltage. At this stage, a voltmeter, test load or indicator screwdriver will be useful. You should not use a single-pole indicator - it is useless. It is prohibited to use an incandescent lamp as an indicator. If exposed to 380V voltage, it may explode and cause injury.
- Next you need to find the damaged part of the wiring.
If you cannot do the work yourself, you should contact an electrician.
Break of neutral conductor with short circuit to phase
If the neutral wire breaks with a short to phase, it is not enough to just turn off the electrical appliances. This will not eliminate the appearance of two phases.
To correct the situation, you need to find the place where the wire damage occurred. Using the indicator, you need to touch metal parts in the walls. The fault should be looked for in the place where the phase was found.
Broken phase conductor
If the indicator in the socket does not show anything, there has been a break in the so-called phase. Its location is easy to determine. It is necessary to check the presence of phase in the junction boxes located between the electrical panel and the damaged socket.
Protection devices
Despite the presence of protective elements (RCDs, circuit breakers), many houses have fuses. If the fuse at “zero” fails, the second phase will go to the sockets.
It is easy to correct the situation if you find the short circuit. It is necessary to turn off the lights, unplug appliances and install a new fuse. If it breaks, the breakdown concerns the wiring. Otherwise, when the fuse is OK, the fault should be sought in the equipment.
Nowadays, instead of fuses, two-pole circuit breakers are installed. With them, two phases may also appear, but only if the device is faulty or incorrectly installed.
Mains faults
Another reason for the appearance of two phases in an outlet is a network failure. More often this is a break in the neutral wire. It can break anywhere, from a substation to a panel in a multi-story building. At the same time, electricity will not be lost in the apartments. In particular difficult cases the voltage will rise to 380 V, which will damage household appliances.
Two phases in an outlet also occur due to a phase/neutral short circuit on the power line. This is a dangerous malfunction, because even RCDs do not always have time to respond. As a result, a fire occurs.
Only electricians should search for and repair power supply faults.
Overvoltage has occurred
Two phases also appear due to voltage surges (increase or decrease) in the network. This manifests itself in the blinking of light, too bright or, conversely, dim light bulbs. An increase is especially dangerous, because the equipment cannot work fully or burns out.
How to proceed:
- Turn off the power supply to the apartment/house.
- Turn off the equipment.
- Turn off the lights (set the switches to the “off” position).
- Call electricians.
Why can't you act on your own? Firstly, the slightest inaccuracy in work can lead to tragic consequences. Secondly, electricity is connected only after a fault report has been drawn up.
Damp walls
Often two phases are a consequence of excess moisture. Damp walls can cause a short circuit. The neutral wire will either fall off or stick to the phase.
To eliminate the breakdown, you need to find the location of the short circuit. Then you will have to change the wires from the outlet to the distribution panel. It is also important to get rid of dampness and prevent its further occurrence.
Induced current
This is a phenomenon that occurs when a high-voltage power line passes nearby. The sockets work fine, but the indicator detects two phases.
In such a situation, an experienced specialist may become confused, because the indicator will determine the voltage even if there is no current in the sockets. A voltmeter or multimeter will show the real picture.
How many phases should there be in an outlet? One, and if there are more, the reasons may be wiring faults (room and substation), high humidity walls, induced current. Regardless of the cause, the malfunction must be repaired by a specialist.
One of the popular electrical wiring faults in an apartment is the appearance of the so-called second phase in the outlet. If the light in the rooms goes out, but all the appliances are working, then you too have become a victim of such a breakdown. Next, we will tell you what to do if there are two phases in the outlet, why this can happen and how to fix the damage yourself!
How does this happen?
In order for you to understand the cause of the malfunction, we will provide a visual:
As you understand, voltage is supplied through the phase wire and returns through the neutral wire. Now imagine what will happen if a zero break occurs:
If you turn on the light switch, the voltage will pass through the filament or a switched-on electrical appliance, go to the neutral wire, etc. the zeros are connected, will go to the socket along the second circuit. The result is that when you check the voltage in the sockets of the socket with a probe, you will see two phases. If you took care of it, there will be no danger to life, you just need to find a break in the neutral wire and restore contact. However, if the electrical wiring was grounded in the apartment, the consequences may not be the best.
Main causes of the problem
As you already understood, the reason for the appearance of two phases on an outlet is most often. Loss of contact can occur on the floor panel, at the entrance to the apartment, in one of the distribution boxes, and even just in the wall.
If the wire burns out in the electrical panel, the lights in the apartment will go out, but the sockets will still work, but only when you turn on an electrical appliance or lighting in the room. If you turn everything off and check the voltage in the outlet, you will see that there will be only one phase.
Another case is when a zero break occurs in the distribution box of one of the rooms. In this case, the light will stop turning on only in this room, in the rest everything will work as before. To solve the problem, you will need to open the junction box and restore it.
Another one common reason, why are there two phases in the socket - old wiring in which plugs are screwed in instead of automatic switches at the input. If only one plug, zero, is knocked out, voltage will appear in two sockets. To prevent this from happening, we recommend replacing the electrical wiring in the apartment with a modern one - with.
There is also a common situation when a break occurs directly in the wall due to your unprofessionalism. Before hanging a picture, be sure to find the electrical wiring in the wall so as not to damage it with a nail (including yourself). If you interrupt only the neutral conductor, two phases will appear in the sockets. This also includes damage to the wire by rodents that may exist in the voids of the panels. apartment buildings. We talked about this in the corresponding article.
So, we told you why voltage may appear in two sockets of an outlet, how this happens and what to do to solve the problem. Now I would like to explain how to immediately understand that wire N has been damaged and it is not both phases, but one that has flowed through the second power line.
The situation is clear - the light went out in the apartment and you immediately decided to use a sampler. Having noticed that the indicator shows the phase on two wires, you thought that these were two phase conductors in your electrical wiring. As we have already said, everything is far from the case and you can verify this as follows:
Using a multimeter, check the voltage in the socket; if it shows 0, then you have only one phase, flowing to the neutral conductor.
This is the most the right way determine the malfunction, because an indicator screwdriver is an extremely inaccurate testing method. The indicator may be triggered and show a second phase, although in reality there will be only one.
The voltage may disappear in the outlet for several reasons:
- there may have been a complete power outage in the house;
- the machine could also turn off in electrical panel what happens sometimes;
- as a result of damage to one or more wire strands in the cable channel;
- broken contact inside the socket;
- melting of the contact inside the socket;
- socket burnout as a result of a short circuit.
You need to make sure that electricity is present on other electrical appliances. Now you need to check the machine in the panel. If it turns off, you can try to turn it back on, since it will either turn on or turn off again if there is a malfunction. Everything of course depends on the reason. If, for example, a short circuit occurs, then you should not turn on the machine until the cause of the short circuit is eliminated. In extreme cases, you will need to call an electrician.
If you write only about sockets, it means that everything is in order with the wiring in the house (in the apartment), the machine works the same way. The only reason is the socket, and we eliminate it.
At the very beginning, turn off the machine; this simply must be done to avoid electric shock. After disconnecting, remove the socket cover; the cover is attached to one bolt.
Now you need to carefully examine the wires, most likely one of them has burned out, maybe it has come out of its place. If it just came out, then screw it back in; if it’s burned out, then remove the black end of the wire (you can use pliers), clean the wire again, and then fasten it in place.
Another reason for a non-working socket is poor twisting of the wires together, you need to eliminate (remove) all the insulating tape from the connection point, then twist the wires again, crimp them with pliers and insulate them.
The socket is installed in the reverse order, we move it apart, use bolts (screws), “tendrils” and fasten the body; if the socket is wobbly, you can put metal under the antennae. The socket must sit firmly on the wall; in extreme cases, you can tighten a screw through the holes on the socket itself, or hammer in nails if the wall allows it (for example, a plaster wall).
Sometimes an interesting fault occurs in electrical wiring that leaves the inexperienced electrician or amateur in a difficult situation. Such a malfunction is the occurrence second phase in the socket, which appears in the place of zero there, which makes you think a lot.
In fact, the same phase is present on both sockets of the socket, since in a single-phase electrical network the 220V alternating voltage is generated by one phase and one neutral conductor, and there cannot be a second phase there. But it is precisely this understanding that causes some bewilderment when a phase is detected in place of the standard zero.
If there really was a second phase in the socket, then the voltage between both phases would be 380V and all switched on household appliances would have to be taken to a repair shop.
A little theory.
Without going into technical details, we can say that a single-phase electrical network is such a method of transmission electric current, when to the consumer (load) alternating current flows through one wire and returns from the consumer through another wire.
Let's take for example closed an electrical circuit consisting of an alternating voltage source, two wires and an incandescent lamp. From the voltage source to the lamp, current flows through one wire and, having passed through the filament of the lamp, making it hot, the current returns to the voltage source through another wire. So, the wire through which current flows to the lamp is called phase or simply phase (L), and the wire through which the current returns from the lamp is called zero or simply zero (N).
When, for example, a phase wire breaks, the circuit opens, the flow of current stops and the lamp goes out. In this case, the section of the phase wire from the voltage source to the break point will be under current or phase voltage(phase). The rest of the phase and neutral wires will be de-energized.
If the neutral wire breaks, the flow of current will also stop, but now the phase wire, both terminals of the lamp and part of the neutral wire extending from the lamp base to the break point will be under phase voltage.
You can use an indicator screwdriver to make sure there is a phase on both terminals of the lamp and on the neutral wire coming from the lamp. But if you measure the voltage on the same terminals and wire with a voltmeter, it will not show anything, since in this part of the circuit there is the same phase, which cannot be measured relative to itself.
Conclusion: There is no voltage between the same phase. There is voltage only between the neutral and phase wires.
Advice. To determine the presence of phase and voltage in the electrical network, it is necessary to use an indicator screwdriver and a voltmeter together. You can use it as a voltmeter.
Now let’s move on to practice and consider some situations with zero that you can independently determine and, if possible, eliminate without involving the utility service:
1. Zero break in the entrance panel of a house or apartment;
2. Zero break at the input or inside the junction box;
3. Short circuit of the neutral conductor to the phase conductor when mechanical damage isolation.
1. Zero break in the entrance panel of a house or apartment.
In the input panel of a house or apartment, the neutral wire may break at the input circuit breaker or on the zero bus. Typically weakened screw connection, due to which contact between the wire and the clamp is lost, or, in rare cases, the neutral wire breaks off at the clamp and hangs in the air.
Also, due to poor contact between the clamp and the wire, the wire heats up and burns and, as a result, a large transition resistance forms between them in the form soot, which gradually turns into a cliff.
In the absence of zero, everything electrical devices they will not work in the house. But if at least one household appliance remains plugged into the socket or the light switch remains on, the phase through radio components of the power supply household appliances or filament lamps will pass unhindered to the zero bus, and from the bus to all neutral wires electrical wiring. And as a result, there will be a phase on both sockets of sockets and contacts of switches. This is because all the neutral wires of the electrical wiring are connected together at the neutral bus.
To determine such a malfunction, it is enough to unplug all household appliances from the sockets and turn off all light switches or unscrew the light bulbs. After these actions, the second phase from the sockets and switch contacts will disappear. The malfunction is treated by restoring the contacts on the terminals of the input circuit breaker or on the zero bus.
2. Zero break at the input or inside the distribution box.
If the neutral wire breaks in front of the distribution box or in the box itself, the problem with the neutral and the operation of electrical equipment will be precisely in the room of the house or apartment into which this box distributes voltage. At the same time, everything in the neighboring rooms will work as normal.
In the figure above you can see that in front of the left distribution box the neutral wire has broken, and the phase through the lamp filament (load) reaches the socket neutral.
When searching for such a fault, the problematic box is opened and the common zero twist is found (it is the thickest in the box). The strands are cut off, re-cut and twisted together again.
Advice. If the wire is copper, then it is advisable to solder the twist.
When the zero breaks in front of the distribution box, as shown in the top figure, to find the break, you often have to open the groove with this wire in the wall to find the location of the damage.
When searching for such a fault, first they find a twist in the box with a common zero and unwind it into separate wires. Then each neutral conductor is called up to the sockets and to the ceiling. The core that will not ring will be the incoming wire into the box.
Next, this wire is pulled through and the plaster in the wall is opened to look for where the wire is damaged. However, such a malfunction is classified as difficult to solve, because few people undertake to pick at the wall - it’s easier to lay a new route.
3. Short circuit of the neutral conductor to the phase conductor in case of mechanical damage to the insulation.
A situation may arise when, when drilling a hole, screwing in a self-tapping screw, or driving a nail into a wall, the electrical wiring. In addition to this, damage to the wiring is accompanied short circuit, due to which the wire is damaged completely or partially. Such a malfunction is treated by opening the damage site and restoring the damaged section of the wire.
Sometimes with such a malfunction you can also observe two phases in the outlet.
At the moment of closure, the phase and neutral conductors are welded together, and therefore the phase freely flows onto the neutral conductor. Moreover, even when the electrical equipment is turned off from the sockets and the lighting switches are turned off, the phase will be present on those sockets and switches that are supplied with voltage from this wire.
The malfunction is treated by restoring the damaged section of the wiring.
If you still have questions, then in addition to the article, watch the video, which also covers the topic of zero loss.
In this article, we examined only the most common faults that occur in a single-phase electrical network when the neutral wire is damaged. Now if you have two phases will appear in the socket, You can easily identify and fix such a malfunction.
Good luck!