Why are there two phases in sockets and how to fix it?
How does this happen?
In order for you to understand the cause of the malfunction, we will provide a visual wiring diagram socket-switch-bulb:
As you know, the voltage is supplied through the phase wire and returns through zero. 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 the included appliance will go into the neutral wire, and so on. the zeros are connected, it will go to the outlet along the second circuit. Bottom line - when checking the voltage in the sockets of the outlet with a probe, you will see two phases. If you have taken care of grounding the apartment, there will be no danger to life, just need to find the open circuit of the neutral wire and restore contact. However, if the apartment used grounding wiring, the consequences may not be the best.
The main causes of the problem
As you already understood, the reason for the appearance of two phases on the outlet is most often zero break. Loss of contact can occur on the floor plate, at the entrance to the apartment, in one of the junction boxes and even just in the wall.
If the wire burns out in the electrical panel, the light will go out in the apartment, but the sockets will also work, but only when you turn on the appliance or the lighting in the room. If you turn everything off and check the voltage at the outlet, you will see that there will be only one phase.
Another case when a zero break occurs in the junction box is one of the rooms. In this case, only the light in this room will stop burning, in the rest everything will work as before. To solve the problem, you will need to open the distribution box and restore wire connection.
Another common reason why the two phases in the outlet are old wiring in which plugs are screwed in instead of circuit breakers at the input. If only one plug is knocked out, zero, voltage will appear in two sockets. To prevent this from happening, we recommend replacing the wiring in the apartment with a modern one - with zero bus.
Also, a situation is often encountered when a cliff occurs directly in the wall due to your lack of professionalism. Before you hang a picture, you must definitely find the wiring in the wall so as not to damage it with a nail (including yourself). If you kill only the neutral conductor, two phases will appear in the outlets. This also includes damage to the wire by rodents, which can exist in the voids of panels of apartment buildings. About, how to protect wiring from rodents, we told in the corresponding article.
We recommend you watch the video, which clearly shows the malfunction:
So, we talked about why voltage can appear in two sockets of the outlet, how this happens and what to do to solve the problem. Now I would like to explain how to immediately understand that there was a damage to the N wire and these are not both phases, but one that flowed along the second line of the power supply network.
Useful advice to readers
The situation is clear - the light in the apartment disappeared and you immediately decided to try it check voltage in outlets. Noticing that the indicator shows the phase on two wires, you thought that these are two phase conductors in your wiring. As we have already said, everything is far from being so and you can verify this as follows:
Using a multimeter, check the voltage in the outlet, if it shows 0, then you have only one phase, flowing to the neutral conductor.
This is the surest way to determine the malfunction, because the indicator screwdriver is an extremely inaccurate verification method. The indicator may trigger and show the second phase, although in reality it will be one.
In the end, we recommend watching another useful video on the topic:
That's all I wanted to tell you about such a wiring malfunction. We draw your attention to the fact that the consequences of such a breakdown can be quite noticeable - if your apartment was used grounding, voltage can pass to the body of electrical appliances, which is extremely dangerous. We hope that now you know what to do if there are two phases in the outlet, how to fix the damage, and why this happens!
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an hour I thought why the two phases turned out to be turned on. your article really helped me. MANY THANKS TO YOU ...
Two phases in the sockets glow when electricians mistakenly put on the tear on the switching devices not a phase, but zero, on the switch, circuit breaker, circuit breaker, which is a gross violation of safety precautions.
In such cases, when you turn off any of the disconnecting devices, in the outlets and even in the lamp holder, the screwdriver indicator will light on two tabs (bottom and side). In fact, there are no two phases there ☺️
ON THE GAP, CONNECT ONLY THE PHASE, NOT THE ZERO.
Hello! You write that during a zero wire break in the apartment itself in the socket through the load, the second phase will appear on its second contact, as I understand it will be the same phase, and 380 in the socket appears after the zero break in the power board of the house itself)))
And yet there is such an option (the case is not typical) when the indicator screwdriver is lit on two contacts of the socket. moreover, the lamps shine normally and all devices work. Further more ... the voltmeter showed 220v. I looked into the shield, and there about ten groups on each there is a dual automatic machine and there is no zero bus in the shield at all ...…. The situation began to clear up when I measured the voltage between the ground and these two lines in turn - 110v. It turned out that in this area of the city, three-phase power supply with phase voltage, for example, is still used. 220v and linear 110v. So two phases nevertheless entered the apartment. It was in Rome 4 years ago.
On the contrary. Phase 110, and linear 220 ...
What should I do if a phase breaks through the frame from the profile (MDF is wired) is it possible to determine the leak location without rubbing the walls and ceiling ????
I beg you, solve this riddle for me:
At the cottage in the house, all sockets and lamp holders are in order, except for the ceiling in the cellar, in which there is a phase on 2 contacts. Between them is a voltage of 0 V.
If you turn on the cellar switch - the cellar lamp does not light. And the phase on the 2 contacts is still there.
We turn off the cellar off, and turn on one of the lamps in the room - there are no more phases in the cellar at both contacts.
And if you then close the cellar off, the cellar lamp burns normally.
What a strange scheme?
The scheme is not strange. Really, you just need to ring or measure the resistance of zero. The wiring is old, apparently the insulation is somewhere damaged and the contacts are broken. The easiest way is if the wiring is external - it is to forward new wires to the cellar.
Say the scheme is not strange. Why are the lamps switched on in series?
In this house, for a very long time, a responsible electrician repeatedly came and looked for hidden illegal wiring, but did not find it. I found one and neutralized. But there are many secrets.
The cable in the ground, going to the bath, the new owners cut off and buried the ends (where they do not remember) because They thought that he was not a worker; they had done such nonsense. Now the new counter from the outside should “absorb” all these layering. According to rumors, the nobleman lived in this house. So the thought crept in that the scheme was strange. By the way, the wiring is internal.
What does “the meter must absorb” take and lay new wires if it is not possible to restore the functionality of all circuits.
Specify, the cellar turns on if the room lamp is on? Does the switch in the room break a phase or zero? If the light in the cellar does not work if the lamp in the room is turned off and works if it is on, then the following question:
Are the lamps turned on in series? What kind of lamps are incandescent? If so, then the brightness of the first when you turn on the cellar would be squandered and the first would not burn without a cellar. And if without turning off the cellar, turn on the switch in the room?
It seems to me that your "noble" electrician put the switch in the neutral wire, and took the zero to the basement to the switch, then with the first lamp open, the cartridge in the cellar will have two phases (see the article for a zero break - it's the same thing, only it imitation).
Then the lamps are turned on not in series but in parallel, just zero is torn by an additional switch. As in the diagram below.
In the first figure, the state when the switches are open. On the second, the room switch is closed.
Conductors on which there is a phase potential in this state are conditionally marked by a red line, is the logic of judgments clear?
First circuit
Second circuit
Good day, there was a problem in the outlet, the outlet is connected directly from the shield without distribution boxes and other circuits. But it shows the voltage at both contacts, even when off. 0. When connected any device it does not work what is the problem?
I was at a loss when I got such crap. Thanks for the available clarification. He himself has never been an electrician, thanks to an article and a video, he found a place of violation of zero contact in the shield, it all worked.
Hello. The house is old, a five-story building, the wiring is old, something was being built on it during cosmetic repairs. She clearly was not getting along (the bulbs burned out, energy-saving ones sometimes sometimes didn’t turn off, etc.) Now they were doing repairs in the kitchen and in the bathroom, and the apartment began to be shocked. The corner at the bathroom when the tiles were laid (the indicator screwdriver burns in this corner when applied to concrete), the wounds are punctured when you wash your hands in the kitchen (the indicator screwdriver burns on the gas pipe, on the mixer washer, on the battery, on the plug in the kitchen the oven is switched off from the outlet! The outlet shows 2 phases. There are also 2 phases in the chandelier room. Nobody knows where the old boxes are. Tell me where to find a specialist who will help you find the breakdown, boxes, etc.
Thank you for the article!
Thanks to her, I found and solved the problem.
Health to you and your loved ones!
Hello!
Thank you for the article, but I have a question. The house (multi-unit) was built in the 95th year, two-wire wiring, i.e. phase and zero. All electrical appliances in the apartment, including light bulbs, are working properly, the lighting does not go out.The usual simple passive indicator screwdriver in all sockets regularly shows zero and phase, and the multimeter - 230 volts. That is, it turns out that everything is normal with the wiring and the neutral wire is not disconnected anywhere. But when using more complex indicators with transistors, LEDs and batteries, miracles begin. In the outlets of some rooms, they regularly show zero and phase, i.e. in the zero socket, the LED is off, and in other rooms the LED is on in both sockets. There are no complaints about the indicators - they are working, but I can’t understand the reason for their such work. Tell me please.
Thank!
Do not use these toys with LED. The single pole indicator must be with a neon lamp. This is not only my personal opinion, but the experience of many electricians with the wrong definition of phases and zeros.
In the first video, there’s some nonsense - the author plugs the multimeter into the outlet, with the machine turned on, and it shows “0.00”! And this despite the fact that the socket and the lamp on separate machines in parallel.
Good afternoon, I’m not an electrician myself, but I understand something. House Khrushchev, there are still old machines, 2 per phase and 2 to zero. In one part of the apartment in the outlet there are 2 phases. At the entrance to the machine shows 220 volts (measured with a multimeter), at the output immediately 2 phases. I tried to throw a separate wire to the first outlet to make sure that it burned out zero in the wall, but the voltage still did not appear. Tell me, please, what is the reason?