To successfully start work related to electricity and determine the phase and zero in the conductors, we will prepare the necessary devices and devices for this:
- digital or its analogue;
- tester (can be replaced with an indicator screwdriver);
- felt-tip pen;
- pliers, side cutters;
- insulating stripper (a tool for stripping insulation from wires);
In addition, the location of the protective equipment should be determined: devices for automatic disconnection of the network or plugs,. Their standard location is on the site, near the apartment and inside. In order to maintain safety, we carry out manipulations with electrical appliances and bare wires, having previously turned off the machine.
Phase and zero measurements with a multimeter
In everyday life, electrical networks for 3 phases are used, supplying a current with a voltage of 380 V to the consumer panel. In houses, mainly, wires with a voltage of 220 V are divorced, because they are connected to zero and one of the phases. Wiring properly installed is grounded.
The voltage between the conductors is measured with a multimeter. Before starting measurements, set the device to the maximum possible AC value with the "~ V" or "ACV" icon and a value exceeding 250 V (as a rule, digital devices are set at 650-900 V).
The measuring contacts simultaneously touch 2 conductors and measure the voltage. The voltage fluctuation in household networks is +/- 10% of 220 V.
You should be extremely careful about the device settings, since upon contact with the phase and zero, with the settings set to measure the resistance indicator, the wiring will close and, probably, injuries and burns will occur.
Determination by external examination
The wiring assembled in compliance with all the requirements can be distinguished by the color of the wires per phase and zero. It is simply recognized that a ground wire with a yellow-green color, a blue or blue sheath is a neutral conductor. Black, white or brown - in such insulations, the sheath of the phase wire is made. Thus, it is checked for the correctness of the connected connections.
Having checked in the instrument panel the correspondence of the connection of the wires to their color coding, you can proceed to the inspection of all junction boxes. Pay attention to twists. Neutral and grounding wires do not twist together, we see by color whether this is so.
If switches are connected to a phase in a junction box, then basically their installation is made with a two-core wire having insulation colors, for example, blue-white and white. This is not something out of the ordinary and is not uncommon.
In the case of installation in the appropriate color combinations of conductors, then we check the phase wire using an indicator screwdriver for this.
Using a screwdriver with indication
Often, in old buildings, wiring is done without a ground wire. In this case, it remains only to determine the phase. This can be easily done with a screwdriver with an indicator. This measurement is based on the fact that there is a light bulb and a resistor (resistance) inside the device.
In the event of a short circuit, a signal flashes. The resistance provided in the screwdriver with indication is designed to carry out measurements safely for humans, reducing the current to non-critical values.
Preparation before using the indicator: the automatic plug on the electric meter is turned off, then we clean the conductors with a knife to a length of 10-15 mm. The ends of the wires are spaced apart to prevent accidental contact.
Switch the machine to the operating position and apply a screwdriver with indication to the stripped conductors in sequence. Having hit the phase wire, in contrast to the zero, the signal diode will light up. The detected phase must be marked with electrical tape or felt-tip pen, in order to make further connections, which should be started with the machine turned off.
When the installation of lighting devices is carried out and the switch has contact with the phase conductor, then it is not necessary to turn off the machine to replace the burned out lamp.
When testing the wiring, the indicator screwdriver is held in the hand in a certain way: the screwdriver is clamped between the middle and thumb of the hand, without touching the bare areas of metal. There is a metal washer at the end of the handle, put your index finger on it. Next, let's test.
Incandescent lamp application
This is a method of using an incandescent lamp to identify the conductors of the corresponding color in a 3-conductor network. This method involves compliance with increased security measures.
To apply this method, an ordinary incandescent lamp is screwed into the socket. Wires that do not have insulation at the ends are screwed onto the cartridge.
If a kit is not available for this method, a standard desk lamp can be used. In this case, in order to get the result, you should alternately connect the conductors to the plug according to the colors.
The disadvantage of this method is that by applying it, it will be impossible to know for sure which of the two phase conductors. That is, by this method, we rather check the system for performance.
And the advantage is that with a high degree of probability we will know the following: 1 wire is zero, the other wire is phase. If the light does not light up during testing, this indicates that there is no phase in the tested conductors.
Measurement of the resistance of the "phase-zero ring"
For planned control and timely detection and elimination of safety violations in the power grid to ensure its normal operation, systematic measurements of the resistance of the phase-zero ring are carried out, since the causes of breakdowns in lighting devices are network overloads and short circuits.
The fastest and most effective way to detect and prevent such cases is to measure the resistance.
Not everyone knows what the concept of "phase-zero ring" means. It means the circuit created by the connection of a neutral conductor located in a grounded neutral. Closing this electrical network forms a phase-zero ring.
Loop resistance is measured:
- Voltage drop in the off circuit.
- Voltage drop due to the resistance of the growing load.
- Inspection for mechanical damage, the wire should be carried out, starting from the point of exit from the walls, it is there that, as a rule, it breaks.
- All current-carrying parts of conductors must have reliable insulation, and the contacts of the sockets are mounted in the case so that there is no possibility of accidental contact with open areas of the body.
- For home use it is enough to get a control lamp and a screwdriver with indication, their cost is not significant. For a person who is sophisticated in electricity, a more expensive device is suitable - a multimeter, since it has a wide range of measured values.
Electrical networks are of two types. AC networks and DC networks. Electric current, as you know, is the ordered movement of electrons. In the case of direct current, they move in the same direction and. as they say, have constant polarization. In the case of alternating current, the direction of motion of electrons changes all the time, that is, the current has alternating polarization.
The AC network is divided into two components: the working phase and the empty phase. Working phase sometimes simply referred to as a phase. Empty is called zero phase or just zero. It serves to create a continuous electrical network when connecting devices, as well as to ground the network. And the phase is supplied with operating voltage.
When the appliance is turned on, it does not matter which phase is working and which is empty. But when installing electrical wiring and connecting it to a common house network, this must be known and taken into account. The fact is that the installation of electrical wiring is done either using a two-core cable, or a three-core cable. In a two-wire one, one core is the working phase, the other is zero. In a three-core, the operating voltage is divided into two cores. It turns out two working phases. The third vein is empty, zero. The common house network is made of a three-core cable. A common room or an apartment is also mainly made of a three-core wire. Therefore, before connecting the apartment wiring, it is necessary to determine the working and zero phases.
Methods for determining phase and neutral wires
It is not difficult to find out which core is energized and which is not. There are several ways to determine phase and zero.
The first way. Phases are determined by the color of the vein sheath... Typically, the working phases are black, brown or gray, and zero is light blue. If additional grounding is installed, then its core is green.
In this case, no additional devices are used to determine the phases. Therefore, this method is not very reliable, because, when installing the wiring, electricians may not follow the color coding of the cores.
Determine phases more reliably with electric indicator screwdriver... It is a non-conductive housing with built-in indicator and. A neon lamp is used as an indicator. When a screwdriver sting touches a bare, energized wire, the indicator, if the core is working, lights up. If zero, then it does not work. With the help of such a screwdriver, you can also determine the health of the network. If the light does not light up when the sting touches the wires in turn, then the network is faulty.
It happens that the indicator lights up when it touches both cores of the wire, that is, to both the phase and zero. This means that there is a break somewhere in the empty phase. It needs to be found and eliminated.Phase detection can be carried out multimeter... First, we set the measurement mode - alternating voltage. Then we grip the end of one probe in our hand. We touch the core with the second probe. If the phase is working, then the voltage value will be shown on the device screen.
You can determine the working phase and using the usual light bulb... We take, screwed into the cartridge, with two pieces of wire. We ground one end. You can ground it by screwing it to the heating battery. Naturally, the ends of the wires should be bare. We touch the vein with the other end. If the light comes on, then the phase is working.
One of the methods showing what phase and zero are in electrics, on video
Thus, the conductor that supplies current to the consumer is called phase conductor. Inside the transformer, the windings are connected in a star with a common point (neutral),. It is supplied to the load with a separate wire. Zero, which is a common conductor, is designed for the reverse flow of current to the source of electricity. In addition, the neutral wire equalizes the phase voltage, i.e. value between zero and phase.
Ground, which is often referred to simply as ground, is not connected to voltage. Its purpose is to protect a person from the effects of electric current at the time of a malfunction with a consumer, i.e. upon breakdown to the case. This can occur if the insulation of the conductors is damaged and if the damaged area of the device body is touched. But since consumers are grounded, when a hazardous voltage occurs on the case, grounding attracts the dangerous potential to the safe ground potential.
How to determine the phase and zero with an indicator screwdriver
One way to find out where the phase and zero are in the outlet or in the power cable is to use. The tool looks like a screwdriver, but inside it has a special filling with an LED. Before starting measurements, you need to turn off the switch through which voltage is supplied to the room. After that, it is required to strip the ends of the tested wires, for which 1.5 cm of insulating material is removed.
To avoid a short circuit between the wires, after turning on the machine, they should be directed in different directions. When all the preparatory measures have been completed, it is necessary to turn on the machine to supply voltage. To understand how to find the phase and zero, you need to follow these steps:
- A screwdriver is clamped between two fingers- medium and large, avoiding touching the exposed part of the tool tip.
- With your index finger, touch the metal tip on the opposite side of the screwdriver.
- The flat end of the indicator is alternately touched to the stripped conductors.
- When the tester touches a phase, the LED will light up. The second wire will correspond to zero. In the absence of indication, initially the conductor will be zero.
How to determine the phase and zero with a multimeter
The device that measures voltage, current and resistance is called. To identify the phase and neutral wire with its help, you first need to configure the device, for which the required measurement limit is selected. In the case of digital devices, set 600, 750 or 1000 " ~ V" or " ACV».
The phase is determined as follows: one of the probes of the device is connected to the contact of the socket or cable, and the second probe is touched with a hand. If the display shows a value of about 200 V, this will indicate the presence of a phase. Readings may vary depending on floor finish, shoes, etc. If the device displays zeros or a voltage within 5-20 V, then the contact corresponds to zero.
How to determine the phase and zero without instruments
Sometimes there are situations when a screwdriver to determine the phase is either not at hand, but you need to find out which wire corresponds to which. Therefore, you should be guided by the color coding of the wires of the power cable. There is a standard for wire marking IEC 60446-2004, which must be adhered to by cable manufacturers, as well as electricians who connect one or another electrical fittings.
To determine which conductor it corresponds to, you need to adhere to the following markings:
- blue or cyan-- zero;
- Brown- phase;
- grounding- green-yellow.
However, the phase wire is not only brown. Other colors are often found, such as white or black, but it will be different from ground and zero. You can visually identify the wires in the junction box, chandelier and other power points.
There is another option, how to determine where the phase and zero are in the absence of instruments. This requires an incandescent lamp with a socket and two small pieces of wires. After connecting the conductors to the socket, you can start working. The edge of one wire touches the pipes of the heating system, the other - the tested conductors. If at the moment of contact the lamp lights up, this indicates the presence of a phase. The pipe for carrying out such an event must be metal, since the plastic does not conduct current.
It should be borne in mind that this method, although it allows you to identify the phase and zero, is dangerous, since there is a high probability of getting an electric shock. Therefore, it is safer for the purposes under consideration to use neon bulbs.
In every house there are electrical appliances and wiring, in the work of which there are some difficulties. Calling a professional electrician for every slightest reason will cost a pretty penny, it is much easier to solve the problem yourself. For these purposes, you may need a multimeter that measures the network parameters. However, the tool is expensive and it is not always advisable to purchase it for home use. Its function can be replaced by an indicator screwdriver. What is it and how do you use it? How to determine where is the phase and where is zero?
Principle of operation
How does the indicator screwdriver work? The appearance of the device is similar to an ordinary screwdriver, but it has an indicator built into the cavity of the handle. The metal part of the screwdriver acts as a probe, while it is able to reduce the power of the supplied electricity so that the use of the device is as safe as possible. The device also has an LED located at the top of the handle. In addition, the screwdriver has a contact-type metal plate.
The principle of operation is quite simple - the probe of the screwdriver touches the conductor of electricity, then, passing through it, the current strength decreases significantly, after which the person touches the contact plate with his finger. The circuit is closed and the light comes on. A screwdriver is needed to show the presence of AC or DC power.
Varieties of screwdrivers
To date, the assortment of any hardware store includes the following types of indicator screwdrivers:
- Safeline multifunctional screwdriver.
- MS 18.
- Lek OP 1.
- Lek OP 2E.
- VM 1141 220 250V.
- Indicator screwdriver with battery.
The presented modifications of the device have some difference in functionality.
Screwdriver options
The standard device is intended for the following purposes:
- Indicator screwdriver indicates phase or zero.
- Determination of hidden wiring in a non-contact way.
- Determination of the location of the cable break.
- Determination of battery polarity.
- Checking the continuity of the electrical circuit.
Depending on the modification of the screwdriver, it may have other additional functions.
Determination of zero and phase
Many novice electricians and people who have decided to independently repair electrical appliances are interested in how to find the phase and zero with an indicator screwdriver. To do this, you should adhere to the following work algorithm:
- first, the wiring is de-energized;
- wires that need to be tested must be stripped from the insulating winding;
- after which it is necessary to turn on the electricity;
- the probe must alternately touch the wires, while remembering that the circuit must be closed with a finger on the contact plate;
- The wire, when touched to which the lamp lights up, is a phase of the electrical circuit.
How to find the phase and zero with an indicator screwdriver in the socket? To do this, you need to alternately place the probe in the holes of the socket. When a phase is detected, the lamp will light up. There will be no light if the screwdriver shows zero. If, when touching both holes of the socket, the light does not light up, this indicates a zero break.
In addition to using an indicator screwdriver, you can determine the phase by the color of the wire:
- the yellow-green wire is the ground;
- phase wire color - black;
- zero has a blue wire.
If the color distribution is not observed, you will need an indicator screwdriver to determine.
Checking the health of incandescent lamps
When buying another incandescent light bulb, it is important to check its performance right in the store. If there is no corresponding stand, this can be done using an ordinary indicator screwdriver. To do this, you need to take the lamp with one hand by the metal base, and with the probe of the indicator screwdriver in the other hand, touch the central contact on the light bulb. If it is working properly, the LED on the device will light up.
Despite the fact that the method is effective, the result may be a failure if the light bulb is depressurized. In this case, the electrical circuit is maintained, but the lamp still does not light up. However, this happens quite rarely.
Checking the heating element
You can check the performance of the heating element of the washing machine without even removing it. It is enough to provide access to the contacts, while the remaining wires must be disconnected. To check, you need to touch one of the contacts of the heating element with your hand, with a screwdriver probe - to the other. In this case, the circuit is closed by touching the metal plate on the device. If the lamp lights up, then the heating element is working.
Checking the voltage in an insulated wire
How does the indicator screwdriver work? Its functionality allows not only to determine the phase and zero, but also to check the voltage in the wires with insulation. It is not recommended to bite an unknown wire, as it is often unclear whether it is energized or not. In this case, the following manipulations are carried out:
- take the indicator screwdriver directly by the probe;
- a metal plate must be attached to the wire;
- if the cable is energized, the indicator on the screwdriver will show this.
This detection method is suitable even for wires that are under plaster, but the glow may be less bright.
Finding a broken wire
The instructions for the indicator screwdriver indicate the multifunctionality of the device. It is very important and convenient for home use. Having figured out how to find the phase and zero with an indicator screwdriver, you can also find a wire break with it. If the carrier suddenly stopped working, then the first step is to check the integrity of the electrical circuit:
Similarly, a wire break is searched for in the house wiring.
Electronic indicator screwdriver
You can find the phase and zero with both an indicator screwdriver with an LED and an electronic one. The differences are only in their design. The electronic indicator screwdriver can be with or without an LCD screen.
Instead of a light signal, such a device notifies the presence of voltage with an audible signal. In addition, a great advantage of such a device is the output of voltage information to the liquid crystal display, if any. The principle of operation of the electronic device is the same as that of a conventional indicator screwdriver.
Functional check
Before determining where the phase is, and where is zero, you need to check the performance of the screwdriver itself, since it, like any other device, may be faulty. To do this, you should pay attention to the following nuances:
- The body of the device must maintain its integrity. Working with electricity requires good insulation without damage.
- Check the screwdriver for accurate readings. To do this, touch a conductor with a probe that is 100% energized.
- If a battery-powered product is used, they must be replaced in time.
Safety when using a screwdriver is extremely important, therefore, if a malfunction is found, it is recommended to purchase a new device. The cost varies from 50 to 1000 rubles. depending on modification.
Security measures
When working with the device, the following safety precautions must be observed:
- Do not disassemble the screwdriver, replace only the batteries, if any.
- Using a damaged screwdriver is strictly prohibited.
- Do not use a device without a screw.
- When the probe comes into contact with electricity, do not touch the bare part of the device with your hands.
- Do not use the device at voltages higher than indicated in the technical specifications.
In order to find out if the phase or zero is on on the indicator screwdriver, you need to follow all the recommendations above. In this case, it is important to monitor the health of the device and not neglect the rules of safe use of the indicator screwdriver.
Very often, when performing repair or installation work related to electricity in an apartment, house, garage or in the country, it becomes necessary to find zero and phase. This is necessary for the correct connection of sockets, switches, lighting fixtures. Most people, even if they do not have a special technical education, imagine that there are special indicators for this. We will take a quick look at this method, and also tell you about another device that no professional electrician can do without. Let's talk about how to determine the phase and zero with a multimeter.
Zero and phase concepts
Before determining phase zero, it would be good to remember a little bit of physics and figure out what these concepts are and why they are found in the outlet.
All electrical networks (both household and industrial) are divided into two types - with direct and alternating current. From school we remember that current is the movement of electrons in a certain order. With a constant current, electrons move in one direction. With alternating current, this direction is constantly changing.
We are more interested in the variable network, which consists of two parts:
- A working phase (usually referred to simply as a "phase"). The operating voltage is applied to it.
- An empty phase, called "zero" in electricity. It is necessary to create a closed network for the connection and operation of electrical devices, and also serves to ground the network.
When we connect devices to a single-phase network, then there is no particular importance where exactly the empty or working phase is. But when we mount electrical wiring in an apartment and connect it to a common house network, you need to know this.
The difference between zero and phase in the video:
The simplest ways
There are several ways to find the phase and zero. Let's consider them briefly.
By color execution of veins
The simplest, but at the same time and the most unreliable way, is to determine the phase and zero by the colors of the insulating sheaths of the conductors. As a rule, the phase conductor has a black, brown, gray or white color version, and zero is made blue or blue. To keep you informed, there are also green or yellow-green conductors, this is how the protective grounding conductors are indicated.
In this case, no devices are needed, they looked at the color of the wire and determined whether this is a phase or zero.
But why is this method the most unreliable? And there is no guarantee that during the installation, the electricians observed the color coding of the cores and did not mix anything up.
Color-coded wires in the following video:
Indicator screwdriver
A more truthful method is to use an indicator screwdriver. It consists of a non-conductive housing and a built-in resistor with an indicator, which is an ordinary neon lamp.
For example, when connecting a switch, the main thing is not to confuse zero with a phase, since this switching device works only for a phase gap. Checking with an indicator screwdriver is as follows:
- Disconnect the general input machine for the apartment.
- Strip the conductors to be checked with a knife from the insulating layer by 1 cm. Separate them to a safe distance from each other to completely exclude the possibility of contact.
- Apply voltage by turning on the input circuit breaker.
- Use the tip of a screwdriver to touch the bare conductors. If at the same time the indicator window lights up, it means that the wire corresponds to the phase one. The absence of a glow indicates that the found wire is zero.
- Mark the required core with a marker or a piece of electrical tape, then turn off the general machine again and connect the switching device.
More complex and accurate checks are performed with a multimeter.
Phase search with an indicator screwdriver and a multimeter in the video:
Multimeter. What is this device?
A multimeter (electricians also call it a tester) is a combined instrument for electrical measurements, which combines many functions, the main of which are an ohmmeter, an ammeter, and a voltmeter.
These devices are different:
- analog;
- digital;
- portable lightweight for some basic measurements;
- complex stationary with a lot of possibilities.
Using a multimeter, you can not only determine the ground, zero or phase, but also measure the current, voltage, resistance on the circuit section, check the electrical circuit for continuity.
The device is a display (or screen) and a switch that can be set in various positions (there are eight sectors around it). At the very top (in the center) there is a sector "OFF", when the switch is set to this position, it means that the device is turned off. To take voltage measurements, you will need to set a switch in the "ACV" (for alternating voltage) and "DCV" (for direct voltage) sectors.
The set of the multimeter includes two more measuring probes - black and red. The black probe is connected to the bottom socket marked "COM", this connection is permanent and is used for any measurements. The red probe, depending on the measurements, is inserted into the middle or upper socket.
How to use the device?
Above, we examined how to find a phase wire using an indicator screwdriver, but it will not work to distinguish between zero and ground with such a tool. Then let's learn how to check the cores with a multimeter.
The preparatory stage looks exactly the same as for working with an indicator screwdriver. With the voltage disconnected, strip the ends of the conductors and be sure to separate them so as not to provoke accidental contact and the occurrence of a short circuit. Apply voltage, now all further work will be with a multimeter:
- Select the measuring range of AC voltage on the instrument above 220 V. Typically, there is a mark with a value of 750 V in the "ACV" mode, set the switch to this position.
- The device has three slots where the test leads are inserted. We find among them the one that is designated by the letter "V" (that is, to measure voltage). Insert the dipstick into it.
- Touch the stripped cores with the probe and look at the screen of the device. If you see a small voltage value (up to 20 V), then you are touching the phase wire. In the case when there is no reading on the screen, you have found zero with a multimeter.
To determine the "ground" clean a small area on any metal element of home communications (it can be water or heating pipes, batteries).
In this case, we will use two sockets "COM" and "V", insert the measuring probes into them. Set the device to the "ACV" mode, to a value of 200 V.
We have three wires, among them we need to find the phase, zero and ground. With one probe, touch the cleaned place on the pipe or battery, with the second touch the conductor. If the display shows a reading of the order of 150-220 V, then you have found a phase wire. For a neutral wire, with similar measurements, the reading fluctuates within 5-10 V, when you touch the "ground", nothing will be displayed on the screen.
Mark each core with a marker or electrical tape, and to make sure that the measurements are correct, now take measurements relative to each other.
Touch two probes to the phase and neutral conductors, a figure should appear on the screen within 220 V. The phase with ground will give a slightly lower reading. And if you touch zero and ground, then the screen will display a value from 1 to 10 V.
A few rules for using a multimeter
Before determining the phase and zero with a multimeter, read a few rules that must be observed when working with the device:
- Never use your multimeter in a humid environment.
- Do not use defective test leads.
- At the time of taking measurements, do not change the measuring limits and do not reposition the switch.
- Do not measure parameters whose value is higher than the upper measuring limit of the device.
How to measure voltage with a multimeter - in the following video:
Pay attention to an important nuance in using a multimeter. The rotary switch must always be set to the maximum position initially to avoid damage to the electronic device. And in the future, if the readings are lower, the switch is moved to low marks to obtain the most accurate measurements.