How to find the phase and zero with the indicator and without instruments

Junction box search

Remembering that the lighting in my apartment is the same, I began to look for the box into which the wire from the bathroom switch goes.

Where does the phase on the bulb come from in this case? correctly, directly from the box, into which the "zero" wires from the switch also come. But first you have to find it.

Any electrician will tell you where the box should be - above the switch. But an experienced electrician will not be so sure of the answer. Looks like I'm getting expert ...

I started looking in an obvious place. The hidden wiring indicator did not help - there was also a wire going to the outlet. He smashed the whole wall. Although it is said loudly - under the layer of plaster there was something like sand. I felt like an archaeologist, only a brush was missing.

There is no box. The wires go into the ceiling slab. The wall has been broken in vain. The owners are shocked.

How to determine the phase and zero with a multimeter or tester

Here, first switch the tester to AC voltage measurement mode. Further, the measurement can be done in several ways:

• pinch one of the probes with two fingers. Connect the second probe to the contact in the socket or switch. If the readings on the multimeter display are insignificant (up to 10 Volts), this indicates that you have touched the neutral conductor. If you touch another contact, the reading will change. Depending on the quality of your device, it can be several tens of volts, as well as from 100V and above. We conclude that there is a phase in this contact.
• if you are afraid to touch the probe with your hands in any case, you can try another way. Insert one rod into the outlet, and with the other just touch the wall next to the outlet. If you have plaster, the result will be similar to the first measurement.
• another way - with one of the probes touch a knowingly grounded surface (the case of a switchboard or equipment), and with the second touch the measured wire. If it is phase, the tester will show the presence of a voltage of 220V.

Safety measures when working with a multimeter:

• be sure to check that the multimeter is turned on in the "voltage measurement" position before determining the phase using the first method (when you pinch the probe with your fingers) - the icon

V or ACV. Otherwise, you may get an electric shock.

some "experienced" electricians use a so-called control lamp to determine the phase. I do not recommend this method to ordinary users, especially since it is prohibited by the rules. Use only serviceable and tested measuring instruments.

In modern apartments, three-core wires go into sockets and junction boxes. Phase, working zero and protective. How to distinguish them from each other can be found in article 4 ways to distinguish a grounding conductor from a zero one.

Modern screwdrivers-indicators will relieve the headache of a person trying to comprehend how to determine the phase, zero, earth. Difficulties are noticed, we will tell below. A signal generated by a screwdriver is used for testing. It is clear that there are batteries inside. An old Soviet indicator screwdriver based on a single gas-discharge lamp is unusable. Allows you to accurately determine the phase. Hence the other circuit is zero or ground.

Using an indicator screwdriver

The sequence of actions depends on which wiring system is installed in the room. Consider the rules for determining the phase and neutral wires in different cases.

Two-wire network

This wiring option is found in older houses. In modern terminology, this system is designated TN-C. Its essence lies in the fact that the neutral working wire, grounded at the supply substation, combines the role of the protective grounding (PEN).In the IT system, there is also only a phase and a working neutral conductor, but it is not used in ordinary residential and industrial premises. In a two-wire network, there is simply no separate ground wire, that is, there is only a phase and zero. It is very simple to determine them: we touch the indicator sequentially to each of the current-carrying conductors, the phase causes the indicator lamp to light up, as shown in the photo below:

The system is outdated. The plug of any modern electrical appliance has three terminals. The wiring must be three-wire, with the exception of the lighting group.

Three-wire network

In this version, three wires enter the house or apartment. Such networks have several varieties. In a TN-S system, the working zero and the protective ground are separated from the supply substation, where both are connected to the working ground. With this type of wiring, the determination of the purpose of the wires can be carried out as follows:

• in the dashboard or in the junction box, use the indicator to determine the wire on which the phase is present;
• the two remaining are working and protective zero (ground), we disconnect one wire of them on the shield;
• if you disconnect the working zero, all electrical equipment in the apartment will stop working, which means that the remaining conductor is earth, or protective ground.

Now it remains to determine in the outlet among the three wires, on which of them is the phase, zero and ground. If it is not possible to find by the color of the insulation, the determination of their functions can be carried out using improvised means, without devices. To do this, you need to take a cartridge with a screwed-in lamp and wires brought out. The definition is carried out as follows. With one conductor from the cartridge we touch the phase wire (the phase has already been found using the indicator), with the second we alternately touch the other two. If the working zero is turned off on the shield, the lamp will light up only when connected to protective ground, and vice versa.

The video below clearly shows how to determine the phase, zero and ground with an indicator screwdriver:

Another variation of the TN system is the TN-C-S wiring. In this case, the neutral wire is split into a working zero and a protective ground at the entrance to the house. Here, to determine the assignment of the conductors, you can apply the procedure described for the TN-S system. An additional opportunity is added, having examined the place of separation of the PEN, to determine where the working and protective zero (ground) are along the cross-section of the conductor in the wire.

If the grounding is performed according to the TT system, the object (private house) has its own grounding device, from which the protective grounding is wired. Under these conditions, as a rule, the phase, zero and ground can be determined by tracing the grounding conductor along the route of its laying.

No instrumentation required

The household should have at least a voltage probe, but if there is none, do not worry, there are ways to determine the ground, zero and phase without instruments.

All you have to do is make a test lamp, something like the one shown in the photo. The lamp should work from 220V and not be too powerful (so as not to blind your eyes).

There are many options for implementing this device, the main thing is to provide reliable insulation in the places where the wires are attached to the lamp and probes. Naturally, if you need to test the wires in the box on the ceiling, you need to make the probes of the appropriate length.

To determine the phase, it is enough to connect one contact of such a probe to the tested wire, and the other to ground. The latter can be metal pipes for heating or cold water. The place on the pipe to which you will touch the test lamp probe must first be cleaned.

The wire, when touched, the lamp will glow, and will be a phase.

A lot of videos have been published on the Internet on how to determine the phase without using any special equipment. For example, using raw potatoes or tap water.We want to warn you that the repetition of such dubious experiments can cause significant damage to your health.

We have described how to determine zero and phase, and to do it with maximum safety, so there is no need to invent new methods.

As you know, the electricity supplied to our house is three-phase. The voltage between any two outputs is 380 V. At the same time, we know that the voltage used in household appliances is 220 V. How does one convert to another?

The neutral wire plays an important role here.
If you measure the voltage between one of the phases and this wire, then it will just be equal to 220 V. In more modern sockets, an additional zero output is provided - this is the so-called protective zero.

A natural question arises as to what is the difference between the two mentioned zeros? The first of them, "working zero" (we are trying to determine it) is a neutral contact on a three-phase installation of a generator substation, connected to a neutral contact of a three-phase installation in a house or a separate entrance.

At the same time, it may not be grounded at all. The main purpose is to create a closed electrical circuit when powering household appliances. In the second case, we are talking about. It is commonly referred to as "protective earth".

Due to the rather complex nature of alternating current, there are some typical views on the neutral wire and grounding, which may not correspond to the real state of affairs:

1. "There is no voltage at all at zero."
   This is not true. It is connected to the neutral connector at the substation and is designed to create a potential difference at the output. Sometimes it is energized.
2. "If there is grounding, then there will definitely not be a short circuit."
   In most cases, this is the case. But if the current rises too quickly, it may not have time to leave through the ground in time.
3. "If in a cable two conductors are the same, and the third is different, then this is most likely ground."
   It should be so, but sometimes it isn't.

What you can do with an indicator screwdriver

Phase and zero check

The phase check is carried out without touching the contact on the body. We touch with a screwdriver to the contact in the socket and that's it.

If the LED is on, this is a phase.

The LED is off - you can touch the contact on the handle. The LED lights up - this is "zero".

Does not light up - the wire is broken. Those. plus of this indicator screwdriver is that you can not only determine the presence of "zero", but also determine the integrity of the wire.

All other measurements are taken by touching the top contact on the screwdriver handle. By touching the contact, you become a section of the chain. The human body "works" as a container, passing microcurrents through itself.

Checking the continuity of the wire

We take the bare conductor of the wire with one hand, apply the screwdriver probe to the other and touch the contact on the handle. The LED is on - the wire is intact. Off - the wire is broken.

Checking the integrity of the heating element

To check the integrity of the heating coil of the heating element, touch one of the contacts of the heating element with your fingers, apply a probe to the second contact and press the upper contact of the screwdriver. If the coil is intact, the LED lights up. If it does not burn, the heating element coil has burned out.

Checking diodes, fuses, incandescent lamps

Also, using an indicator screwdriver, you can check the fuse, incandescent bulbs, resistors, capacitors, diodes, LEDs. In the case of working diodes, the screwdriver will glow only in "one direction". Also with LED.

The presence of voltage on an insulated wire

There is another interesting function of the contact indicator screwdriver - it can detect the presence of voltage on an insulated conductor. To do this, press the contact on the handle to the conductor and lead it along the wire. If there is voltage in the wire, the diode in the screwdriver will glow, if there is no voltage, the diode will not glow.

Finding a broken wire

The same function allows you to find the place of a wire break: at the point of a wire break, the LED stops lighting. How to find the place of the cliff. We find the phase in the outlet. Next, we determine which of the wires is broken and we connect it to the phase of the outlet. Next, we run with an indicator screwdriver along the wire - the diode glows with a constant light, at the break point the diode stops glowing - here is the break point. But a broken wire in the wall can be determined only with the help of special devices.

Find hidden wiring

Another cool feature: this indicator screwdriver allows you to find hidden wiring. To do this, we drive the back of the screwdriver along the wall where we expect to find the wires. We will see the wires only if they are energized. And at a depth of no more than 1.5 cm. Whoever has the wiring deep in the wall - you can screw a piece of single-core wire 10-15 cm long (like an antenna) to the tip of a screwdriver, then the sensitivity of the screwdriver will increase!

To prevent the batteries in the screwdriver from sitting longer, you need to put a cap on the tip of the screwdriver.

The most affordable and common ways

The simplest method, which allows you to accurately determine the phase and neutral wire, is performed with an indicator screwdriver. You can buy it or assemble it yourself. The diagram of such a device is simple, it is shown in the figure below.

Designations on the diagram:

• A - contact plate;
• B - detector tip;
• R1 - resistance with a nominal value from 1.5 to 2 MΩ, power from 0.5 W;
• HG1 - any type of neon lamp.

Video instruction: determining phase and zero with an indicator screwdriver

The compact dimensions of the parts used allow the device to be assembled in a ballpoint pen housing. Industrial designs resemble a small screwdriver in appearance.

Determination of the connection of a wire to a phase or zero phase (in a two-wire circuit) is performed according to the step-by-step algorithm described below
:

1. the wiring is de-energized;
2. a protective layer of insulation is removed from the wires to be tested (one centimeter will be enough);
3. we turn on the electricity, since it will not work to determine zero if the phase is disconnected;
4. with the tip of the probe, two wires are checked in turn, touching the contact plate of the indicator, as shown in the photo;
5. if the neon lamp lights up, the tested core is a phase of the electrical circuit.

In the outlet, the voltage indicator works on two contacts

The situation when the probe detects two phases in the outlet and does not see zero can be confusing for a novice electrician. The matter becomes even more confusing if you measure the potential difference with a multimeter or tester. They will show that there is no voltage. These are characteristic signs of a zero break.

Note that with external signs of a lack of voltage in the wiring (according to the readings of the multimeter), you can get a rather noticeable electric shock. This is why the voltage probe should not be neglected.

To solve this problem, it is enough to eliminate the break in the neutral wire, if you do not know how to do this, it is better to entrust this work to professional electricians.

Determination with a multimeter or tester

To begin with, it is best to determine the phase with a screwdriver combined with an indicator. We will proceed from the fact that if the farm has a multimeter, the indicator will be found for sure. As a last resort, you can do the following. In some cases, determining with a multimeter the voltage between the wire and the heating or water supply pipe can help. Unfortunately, the result is not always predictable here. Most often, the voltage between the phase and the heating system is close to 220 V, in any case, it should be higher than between the same heating and zero. The picture can change, for example, if a thieving neighbor uses heating pipes as a working ground.

In three-wire circuits, the multimeter will show the operating voltage between the conductor that is connected to the phase and either of the other two.The determination of which zero is working and which is the ground can be carried out according to the method described above, that is, by disconnecting one of the arriving zeros on the dashboard and using a control lamp.

Determination methods

Consider ways to determine the neutral and grounding conductors, from very simple to more
complicated.

The circuit has a diff-current protection... If the entire object or the branch under study is protected by
differential current - diff-automatic or RCD, the task is greatly simplified. You need a control
the device, for example a lamp with conductors, is connected to the phase and to one of the investigated conductors. If
diff-protection did not work, which means the lamp is connected to working zero. If an RCD is triggered
when connecting a lamp - you connect it to phase and ground. Everything is quite simple and at the same time check
residual current device in practice.

Before performing such a test, you need to make sure that the diff protection is working by pressing the "test" button on
protective apparatus. It should be noted that the method will work provided that the current through the lamp is
exceed the rated residual current of the device. That is, when using an incandescent lamp
(energy saving is not suitable) the RCD with a leakage current of 10-30 mA will work. Introductory RCD for leakage 300 mA
may not work, for a reliable check you need to take a more powerful device.

Comparison with grounding contacts of sockets... This method will work if the input is
a two-pole circuit breaker that breaks the working zero and there are sockets with grounding in the room. Introductory
the machine should be turned off, thereby we will open any connection between zero and ground. If possible, you should
disconnect all appliances from the sockets.

Next, you should "ring" the ground contact with a multimeter in the resistance measurement mode
one of the sockets with the contacts under test. When connected to a neutral wire, the multimeter should
show high resistance, with a ground contact at an unknown point with the ground of the outlet
resistance is practically zero.

In this way, you can at the same time check the correctness of the connected sockets: with the input
a two-pole machine, zero and grounding contacts should not ring. Well this is provided
that the wiring is initially in good order and correctly mounted.

Climb into the shield... If the previous methods are not possible to implement, you will have to go into the "stuffing"
electrical panel. I think it's not worth reminding here of safety precautions: no one has canceled it. In fact
in fact, the method is quite simple: you need to find a neutral conductor that goes into the room and disconnect
it from the terminals of the shield. Then call the investigated contacts: with whom the call will be - that is
neutral conductor.

In the case of a shield, it may well be difficult when, even in a shield, it is difficult to distinguish zero from grounding.
In this case, a current clamp is needed. It is necessary to turn on the voltage and load in the room, and
to investigate unknown conductors in the shield with clamps - where the current will be, and the working zero

Note:
the method only works when you know for sure that one of the conductors is zero and the other is
Earth.

All of the above methods work both with grounding and with "zeroing"

Determine the contacts when connecting the electric stove... Sometimes it becomes necessary to replace the socket
electric stoves, and the wiring of the Soviet era or the early 90s, one-color. For the correct determination of zeroing
electric stoves, a condition is necessary - a two-pole circuit breaker in the input board, which disconnects both the phase and zero from the entire
apartments.

So, with the power on, we determine the phase on the studied conclusions for the future socket - this contact
we mark it and put it aside, then we do not need it. Then you need to determine zero in any outlet in the apartment -
since the wiring is Soviet, there is no land there, so the terminal on which it does not light will turn out to be zero
screwdriver indicator.

Now we de-energize the entire apartment and use a multimeter to ring the zero of an ordinary outlet with two remaining contacts
on the electric stove. The contact that rings with the zero of the socket is working, and the one that does not ring is zero (ground).
If both contacts are ringing, you need to look for errors in the wiring. When organizing grounding in Soviet times,
it was connected to the "PEN" terminal without any switching devices.

Determination of zero and phase

In order not to confuse zero and phase on the switch, or when carrying out other electrical work, you need to use special phase-indicating instruments or probes. The easiest way is to use an indicator screwdriver.

Indicator screwdriver

To know how to determine the phase and zero with an indicator screwdriver, you need to understand the principle of its operation. It is configured in such a way that the internal neon lamp lights up when there is a potential difference between the working contact of the screwdriver and the metal terminal at the end of its handle. To correctly indicate the phase with a screwdriver, you need to follow simple steps:

1. Disconnect the power supply from the mains automatically;
2. Strip the ends of the tested conductors and separate them to a safe distance;
3. Apply power to the mains;
4. Touch the tip of the probe to the end of the test conductor;
5. Press with your finger on the metal terminal at the end of the screwdriver handle; it is forbidden to touch the tip of the screwdriver during operation;
6. If the phase is being tested, the lamp inside the probe should light up.

In addition to the usual indicator, there is a screwdriver for dialing. It differs in that it contains batteries and indicates the phase without touching its opposite metal end with your finger. There is also an indicator screwdriver with hidden wiring detection function. She can determine where the electrical network of the apartment runs inside the wall. It uses a non-contact method for determining the electromagnetic field that occurs around the conductor.

Control lamp

Another way to determine the phase and zero without instruments is to make a test lamp. Such an indicator is created simply: you need to solder wires of sufficient length to the terminals of the cartridge and screw an incandescent or neon lamp into it. One of the terminals of such a phase detector is connected to the battery, and the second one can check the presence of the supply voltage in the network. To do this, touch the tested conductor with the stripped end of the wire. If this is a phase, the lamp should flash. This method is very dangerous, therefore, it should be used only in exceptional cases, moreover, it is prohibited by the Rules for the Safe Operation of Electrical Installations.

Measurement with a multimeter

In the absence of an indicator screwdriver and for more accurate measurements of the mains supply voltage, a multimeter is used, it is also called a tester. With it, you can determine the phase, neutral and ground conductors in a three-wire network. The fact is that the indicator screwdriver can only show large differences in potentials, that is, it shows only the phase. The multimeter works with different signals: high and low level, positive and negative. Its task is to show the parameters of the electrical circuit.

To find out how to find the phase and zero with a multimeter, as well as the ground wire, you need to correctly configure and connect this measuring device. It is done like this:

1. Install the black probe of the multimeter into the socket marked COM, and the red probe into the socket labeled U, Ω, Hz;
2. Use the knob on the front panel to select the AC measurement mode, the measurement limit is greater than 220 V.

After adjustment, you need to simultaneously touch the two ends of the probes to the two test leads. The value on the multimeter screen:

• More than 100 V - phase and zero found;
• More than 160 V - phase and ground line found;
• Less than 70 V is zero and ground.

Having tested all three lines in this way, one can confidently determine where the desired potential is present.

An easier way, how to determine the phase with a multimeter, is to alternately touch all ends of the power network with a probe installed in the U, Ω, Hz hole. In case of contact with the phase conductor, the multimeter will show a voltage of 8-15 V. In other cases, the readings will be at the level of 0-3 volts

Use the multimeter with care, using insulating shoes and never touch the ends of the non-insulated probes with your hands.

During any work with electrical wiring, safety precautions must be observed, that is, de-energize the room when installing and repairing an electrician, and during a performance test with the machine turned on, provide yourself with reliable insulation protection.

Originally posted 2018-04-18 12:26:17.

How to distinguish between grounding and neutral wire when the phase is disconnected?

Suppose there is no current in the network. Is there any difference in this case between ground and neutral? At first glance, it may seem that they are very similar to each other.

In fact, their functions are still different. Grounding is for emergency situations. Through it, the electric charge goes into the ground. The neutral wire is part of the electrical circuit for powering household electrical appliances in the house.

Here, the current, as opposed to grounding, is present. How can you tell them apart? With the phase off, you just need to measure the current between this wire and an accurately known ground. If this is a neutral wire, then the current, although small, will be in this case. If there is grounding, then there can be no current here.