And in everyday life we use, as a rule, single-phase. This is achieved by connecting our wiring to one of the three phase wires (Figure 1), and for further consideration of the material, which phase comes into the apartment is completely indifferent to us. Since this example is very schematic, we should briefly consider the physical meaning of such a connection (Figure 2).
Electric current occurs when there is a closed circuit electrical circuit, which consists of the winding (Lt) of the substation transformer (1), the connecting line (2), and the electrical wiring of our apartment (3). (Here the designation of phase is L, zero - N).
Another point - in order for current to flow through this circuit, at least one electricity consumer Rн must be turned on in the apartment. Otherwise, there will be no current, but the VOLTAGE on the phase will remain.
One of the ends of the Lt winding at the substation is grounded, that is, it has electrical contact with the ground (Zml). The wire that comes from this point is neutral, the other is phase.
This leads to another obvious practical conclusion: the voltage between “zero” and “ground” will be close to zero (determined by grounding resistance), and “ground” will be “phase”, in our case 220 Volts.
Moreover, if hypothetically ( In practice this cannot be done!) ground the neutral wire in the apartment, disconnecting it from the substation (Fig. 3), the voltage “phase” - “zero” will be the same 220 Volts.
We figured out what phase and zero are. Let's talk about grounding. I think its physical meaning is already clear, so I propose to look at it from a practical point of view.
If, for some reason, electrical contact occurs between the phase and the conductive (metal, for example) body of an electrical device, voltage appears on the latter.
When you touch this body, an electric current may flow through the body. This is due to the presence of electrical contact between the body and the “ground” (Fig. 4). The lower the resistance of this contact (wet or metal floor, direct contact building structure with natural grounding conductors (heating radiators, metal water pipes) the greater the danger you face.
The solution to this problem is to ground the housing (Figure 5), in which case the dangerous current will “disappear” through the grounding circuit.
Structurally, the implementation of this method of protection against damage electric shock for apartments, office premises consists of laying a separate PE grounding conductor (Fig. 6), which is subsequently grounded in one way or another.
How this is done is a topic for a separate discussion; for example, in a private house you can make a grounding loop yourself. Exist various options with their own advantages and disadvantages, but for further understanding of this material they are not fundamental, since I propose to consider several purely practical issues.
HOW TO DETERMINE PHASE AND ZERO
Where is the phase, where is the zero - a question that arises when connecting any electrical device.
First let's look at how to find the phase. The easiest way to do this is with an indicator screwdriver (Figure 7).
With the conductive tip of the indicator screwdriver (1) we touch the controlled section of the electrical circuit (during operation, contact of this part of the screwdriver with the body is unacceptable!), with a finger we touch contact pad 3, the glow of indicator 2 indicates the presence of a phase.
In addition to an indicator screwdriver, the phase can be checked with a multimeter (tester), although this is more labor-intensive. To do this, the multimeter should be switched to AC voltage measurement mode with a limit of more than 220 Volts. With one probe of the multimeter (it doesn’t matter which one) we touch the section of the circuit being measured, with the other we touch the natural ground electrode (heating radiators, metal water pipes). When the multimeter readings correspond to the network voltage (about 220 V), there is a phase in the measured section of the circuit (diagram Fig. 8).
I draw your attention to the fact that if the measurements taken show the absence of a phase, it cannot be stated that this is zero. Example in Figure 9.
- Now there is no phase 1 at point.
- When the switch S is closed, it appears.
Therefore, you should check all possible options.
I would like to note that if there is a grounding wire in the electrical wiring, distinguish it from the neutral conductor using the method electrical measurements impossible within the apartment. As a rule, the wire used for grounding is yellow green color, but it is better to verify this visually, for example, remove the socket cover and see which wire is connected to the ground contacts.
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Designation L and N in electrics
Every time you try to connect a chandelier or sconce, a light or motion sensor, a hob or an exhaust fan, a heated floor thermostat or an LED strip power supply, as well as any other electrical equipment, you can see following markings near the connection terminals – L and N.
Let's figure out what the designations L and N mean in electrical engineering.
As you probably guessed, these are not just arbitrary symbols, each of them carries a specific meaning and serves as a hint for correctly connecting the electrical appliance to the network.
Designation L in electrical
“L” - This marking came to electrical engineering from the English language, and it is formed from the first letter of the word “Line” (line) - the generally accepted name for a phase wire. Also, if it is more convenient for you, you can focus on such concepts of English words as Lead (lead wire, core) or Live (under voltage).
Accordingly, the designation L marks the clamps and contact connections intended for connecting the phase wire. In a three-phase network, alphanumeric identification (marking) of phase conductors “L1”, “L2” and “L3”.
By modern standards ( GOST R 50462-2009 (IEC 60446:2007), valid in Russia, the colors of the phase wires are brown or black. But often, there may be white, pink, gray or a wire of any other color except blue, white-blue, cyan, white-blue or yellow-green.
Designation N in electrical
“N” is a marking formed from the first letter of the word Neutral (neutral) - the generally accepted name for the neutral working conductor, in Russia more often called simply the neutral conductor or briefly Zero (Zero). In this regard, it is well suited English word Null (zero), you can focus on it.
In electrical engineering, the designation N marks clamps and contact connections for connecting the neutral working conductor/neutral wire. Moreover, this rule applies to both single-phase and three-phase networks.
The wire colors that mark the neutral wire (zero, zero, zero working conductor) are strictly blue (blue) or white-blue (white-blue).
Grounding Symbol
If we are talking about the designations L and N in electrics, we cannot help but note this sign - which can also almost always be seen together with these two markings. This icon marks clamps, terminals or contact connections for connecting wires (PE - Protective Earthing), also known as neutral protective conductor, grounding, earth.
Generally accepted color coding neutral protective wire – yellow-green. These two colors are reserved only for ground wires and are not used to designate phase or neutral wires.
Unfortunately, often the electrical wiring in our apartments and houses is not carried out in compliance with all strict standards and rules for color and alphanumeric markings for electricians. And knowing the purpose of the L and N markings on electrical equipment is sometimes not enough for proper connection. Therefore, be sure to read our article “How to determine phase, zero and grounding yourself, using improvised means? “If you have any doubts, this material will come in handy.
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The transition to the usual voltage of 220 V was carried out back in the years of its existence Soviet Union and ended in the late 70s, early 80s. Electrical networks of that time were made according to a two-wire circuit, and the wire insulation was monochromatic, mostly white. Subsequently, high-power household appliances appeared that required grounding.
The connection diagram gradually changed to a three-wire one. GOST 7396.1–89 standardized the types of power plugs, bringing them closer to European ones. After the collapse of the USSR, new standards were adopted based on the requirements of the International Electrotechnical Commission. In particular, to increase safety when working in electrical networks and simplify installation, color grading of wires was introduced.
Normative base
The main document describing the requirements for the installation of electrical networks is GOST R 50462–2009, which is based on the IEC 60446:2007 standard. It sets out the rules that the color marking of wires must comply with. They concern manufacturers of cable products, construction and operating organizations whose activities are related to the installation of electrical networks.
Extended installation requirements are contained in the Electrical Installation Regulations. They contain the recommended connection procedure, with reference to GOST-R in paragraphs regarding color gradations.
The need for color separation
A two-wire system implies the presence of a phase and a zero in the network. The plug for such sockets is flat. The equipment is designed in such a way that the correct connection does not matter. It doesn’t matter which contact the phase is applied to, the equipment will figure itself out on its own.
With a three-wire system, an additional grounding conductor is provided. At best, incorrect connection of wires will lead to constant operation circuit breaker, at worst - to equipment damage and fire. The use of color gradation for cores eliminates installation errors and eliminates the need to use special devices, designed to measure the resulting voltage.
Three-wire system
Let's look at a cross-section of a three-core wire, which is used for laying household electrical networks.
The color of the wires indicates where the phase, neutral and ground are located. Additionally, the figure shows typical letter symbols used in electrical circuits. By picking up such a drawing, you can visually determine the correctness of the connection.
Let's take a look at GOST and see how well the color coding of wires shown in the figure meets the requirements. Clause 5.1 general provisions contains a description of the twelve colors that should be used for marking.
Nine colors are allocated to indicate phase wires, one for neutral and two for grounding. The standard provides for a grounding wire in a combined yellow-green design. Longitudinal and transverse application of stripes is allowed, and the predominant color should not occupy more than 70% of the braiding area. The separate use of yellow or green in a protective coating is expressly prohibited by clause 5.2.1.
This scheme is used when single-phase connection, suitable for most electrical appliances. It is almost impossible to get confused in it, with a correctly marked wire.
Five-wire system
For a three-phase connection, five-core wires are used. Accordingly, three wires are allocated for phases, one for neutral or zero and one for protective, grounding. Color marking, as in any alternating current network, is similar, in accordance with GOST requirements.
In this case there will be correct connection phase conductors. As can be seen in the figure, the protective wire is made in a yellow-green braid, and the neutral wire is in blue. Allowed shades are used for the phases.
Using five-core wires, you can connect a 380 V network with correct wiring.
Combined wires
In order to reduce the cost of production and simplify connections, two- or four-core wires are also used, in which the protective conductor is combined with the neutral conductor. In the documentation they are designated by the abbreviation PEN. As you guessed, it consists of letter designations neutral (N) and ground (PE) wires.
GOST provides special color markings for them. Along their length, they are painted in the colors of the grounding conductor, that is, yellow-green. The ends must be painted blue, which additionally marks all joints.
Since the places where the connection is made cannot be determined in advance, at these points the PEN wires are isolated using insulating tape or cambrics of blue color.
Non-standard wires and markings
When purchasing a new wire, you will, of course, pay attention to the color marking of the cores and choose the option where it is applied correctly. What to do if the wiring has already been completed, but the colors of the wires do not meet the requirements of GOST? The output in this case is the same as with PEN wires. You will have to perform manual marking after you have decided on the role played by the conductors suitable for the equipment. A simple option would be to use colored electrical tape in appropriate shades. At a minimum, it is worth identifying the protective and neutral wires.
At professional installation it is possible to use special cambrics, which are hollow sections insulating material. They are divided into regular and heat-shrinkable. The latter do not require selection by diameter, but do not have the possibility of reuse.
There are also specially made markers with international alphanumeric designations. They are used on input and distribution boards, for example, in apartment buildings or administrative buildings.
Digital tags, together with the color of the wire, allow you to determine which consumer is supplied with power.
Additional requirements
Since lines, like wiring, can be made using different cable products, there are a number of rules for their mutual connection. The connection of a three-wire cable to a five-wire cable must be carried out in compliance with the color markings from master to slave. Accordingly, the grounding and neutral colors must match.
Phase connection, in this case, is performed using a unifying bus. On the one hand, three cores are connected to it, on the other hand - one, which will be the phase in the new branch.
When installing household electrical networks, according to safety requirements, it is prohibited to use wiring with aluminum or multi-wire conductors. Only solid copper cable should be used.
Three-wire DC system
In DC systems, a three-wire system is also used, but the purpose of the wires is different. The division is made into positive, negative and protective. According to GOST, the following color markings are used in such networks:
- Plus - brown;
- Minus - gray;
- Zero - blue.
Since separate wires for the systems direct current It is irrational to produce; the indicated color gradation is used mainly for painting conductive busbars.
Finally
As you can see, the colors of electrical wires are not a whim of the manufacturer, but a measure aimed at ensuring safety requirements. If you follow the installation rules, it is much easier to maintain such networks, and not only an electrician, but also you and me can figure out the connection.
Video on the topic
Every time I install an outlet or connect some stationary device, the question arises: what does the color of the wire mean - phase? Or is it earth? Adding to the confusion is the fact that not all cables are our native VVG-3 with white, blue and yellow-green wires. There are also Chinese with combinations of gray + brown + white, and there are also complex multi-core cables that can only be dealt with using an electrician’s handbook.
In everyday life there is nowhere to get all these encodings, so we will focus on the most simple wiring. A simple one is a cable of three cores and a household task, for example, installing an outlet.
Standard household wire with white, blue and yellow-green colors
Coding, marking and history
The idea of dividing wires by color is not new - the very first experiments, as old textbooks tell us, were carried out with multi-colored terminals and wires. The same uncomplicated simplicity remains in cars - you can hardly confuse the blue and red wires. True, he is sometimes black, but that's a completely different story.
When studying wiring, the most important ones to determine by wire color are not the phase, but the ground and zero; the phase can always be found using a detector screwdriver or (almost) any diode. But sometimes it becomes simply dangerous to confuse the colors of earth and zero, and it is necessary to determine in advance what color of wire phase zero-ground is.
Phase wire color
As previously stated, there is no particular need to determine the phase by color - you almost always have access to one or another tool for determination. A certain “zoo” in colors is observed due to the fact that there are advanced, non-household standards for the color differentiation of wires; they are used by real electricians. For example, brown indicates that the wire is for outlets, while red indicates that the wire is for lighting. The load depends on this and valid parameters work.
Ground wire color
Grounding is the most uncontested wire; it is always yellow-green in color. There are deviations, for example, pure yellow - when the wire is imported. They write on the network that there is a yellow-green-blue color of the wire, which denotes the combined working zero and ground.
Zero wire color
The minus has a small selection of colors - usually it is a blue wire, which is found in almost any cable, or (very rarely) red/cherry. As was said about the ground, it is strictly not recommended to confuse these wires.
Conclusion
We fix the general color scheme:
- Ground - wire color yellow-green or yellow wire color;
- Zero - blue;
- Phase - wire color white, red, brown and any other unfamiliar ones.
In order to facilitate the installation of electrical wiring, all cable and wire products have appropriate multi-colored markings. As a rule, in houses or apartments, lighting is installed and sockets are connected using three wires. Each of them has its own purpose in the home electrical network. Therefore, the designation of the color of the ground wires has great importance. Due to this, installation time and subsequent repairs are significantly reduced. Thanks to color coding, any type of connection is not particularly difficult.
Ground wire
In most cases, the color yellow-green is used to indicate the ground wire. Sometimes you can find conductors with insulation only yellow color. Even less commonly used is light green. Typically, such wires are marked with PE symbols. However, if the ground wire is aligned with the neutral, it is designated as PEN. It is colored green-yellow and has a blue braid at the ends.
In the distribution panel, the grounding wire is connected to a special busbar, or to the housing and metal door. In the distribution box, the connection is made with similar wires provided in lamps and sockets equipped with special grounding contacts. The grounding wire does not need to be connected to a residual current device (RCD), therefore such protective devices used where only two wires are used for electrical wiring.
Neutral conductor (neutral)
The color blue is traditionally used for the neutral conductor or neutral. The connection in the distribution panel is made through a special zero bus, designated by the symbol N. All blue wires are connected to this bus.
The bus itself is connected to the input via. In some cases, the connection can be made directly, without any additional automatic devices.
In the distribution box, all neutral blue wires are connected together and do not take part in switching. The exception is the wire coming from the switch. Connecting blue wires to sockets is done using a special zero contact, designated by the letter N. This marking is affixed to the back of each socket.
Phase wire color
The phase does not have any precise designation. Black, brown, red and other colors other than green, yellow and blue are quite common. In the distribution panel installed in the apartment, the connection of the phase wire coming from the consumer is made with a contact circuit breaker, located below. In other circuits, this conductor may be connected to a residual current device.
In switches, the phase is directly involved in switching. With its help, the contact is closed and opened - turned on and off. In this way, voltage is supplied to consumers, and, if necessary, this supply is stopped. In sockets, the phase conductor is connected to the contact marked L.
Wire Definition
Sometimes situations arise when it is necessary to determine the purpose of a particular wire if there is no marking on it. The simplest and most common way is. With its help, you can accurately determine which wire will be phase and which will be neutral. First of all, you need to turn off the power supply to the panel. After this, the ends of the two conductors are stripped and separated to the sides away from each other. Then you need to turn on the electricity supply and use the indicator to determine the purpose of each wire. If the light bulb lights up upon contact with the core, this is a phase. This means the other core will be neutral.
If there is a ground wire in the electrical wiring, it is recommended to use a multimeter. This device is equipped with two tentacles. First the measurement is established alternating current in the range of more than 220 volts at the corresponding mark. One tentacle is fixed at the end of the phase wire, and the second one determines grounding or zero. In case of contact with zero, the device display will display a voltage of 220 volts. When you touch the ground wire, the voltage will be noticeably lower.
Marking
There is not only the color of the wires phase, zero, ground, but also other types of markings, primarily alphabetic and digital designations. The first letter A indicates the wire material - aluminum. If this letter is missing, the core material will be copper.
Basic marking of wires in electrical engineering:
- AA - corresponds to stranded aluminum cable with additional braiding made of the same material.
- AC - additional lead braid.
- B - the presence of protection from moisture and additional braiding made of two-layer steel.
- BN - non-flammable cable braid.
- G - absence of a protective shell.
- R - rubber shell.
- HP - rubber shell made of non-flammable material.
Very few people understand the essence of electricity. Concepts such as “electric current”, “voltage”, “phase” and “zero” are for most dark forest, although we encounter them every day. Let's get a grain of useful knowledge and figure out what phase and zero are in electricity. To teach electricity from scratch, we need to understand the fundamental concepts. We are primarily interested in electric current and electric charge.
Electric current and electric charge
Electric charge is a physical scalar quantity that determines the ability of bodies to be a source of electromagnetic fields. The carrier of the smallest or elementary electric charge is the electron. Its charge is approximately -1.6 to 10 to the minus nineteenth power of Coulomb.
Electron charge is the minimum electrical charge (quantum, portion of charge) that occurs in nature in free, long-lived particles.
Charges are conventionally divided into positive and negative. For example, if we rub an ebonite stick on wool, it will acquire a negative electrical charge (excess electrons that were captured by the atoms of the stick upon contact with the wool).
Static electricity on the hair has the same nature, only in this case the charge is positive (the hair loses electrons).
The main type of alternating current is sinusoidal current . This is a current that first increases in one direction, reaches a maximum (amplitude), begins to decrease, at some point becomes equal to zero and increases again, but in a different direction.
Directly about the mysterious phase and zero
We have all heard about phase, three phases, zero and grounding.
The simplest case of an electrical circuit is single phase circuit . It only has three wires. Through one of the wires the current flows to the consumer (let it be an iron or hair dryer), and through the other it returns back. The third wire in a single-phase network is earth (or grounding).
The ground wire does not carry a load, but serves as a fuse. In case something gets out of control, grounding helps prevent electric shock. This wire carries excess electricity or “drains” into the ground.
The wire through which current flows to the device is called phase , and the wire through which the current returns is zero.
So, why do we need zero in electricity? Yes, for the same thing as the phase! The current flows through the phase wire to the consumer, and through the neutral wire it is discharged in the opposite direction. The network through which alternating current is distributed is three-phase. It consists of three phase wires and one return.
It is through this network that the current flows to our apartments. Approaching directly to the consumer (apartments), the current is divided into phases, and each phase is given a zero. The frequency of changing the direction of current in the CIS countries is 50 Hz.
IN different countries There are different standards for voltages and frequencies in the network. For example, a typical household outlet in the United States supplies alternating current with a voltage of 100-127 Volts and a frequency of 60 Hertz.
The phase and neutral wires should not be confused. Otherwise, you can cause a short circuit in the circuit. To prevent this from happening and to prevent you from confusing anything, the wires have acquired different colors.
What color are phase and zero indicated in electricity? Zero is usually blue or blue color, and the phase is white, black or brown. The ground wire also has its own color - yellow-green.
So, today we learned what the concepts of “phase” and “zero” mean in electricity. We will be simply happy if this information was new and interesting for someone. Now, when you hear something about electricity, phase, zero and ground, you will already know what it is about we're talking about. Finally, we remind you that if you suddenly need to calculate a three-phase AC circuit, you can safely contact . With the help of our specialists, even the wildest and most difficult task will be up to you.
To facilitate the installation of electrical wiring, the cables are manufactured with multi-colored wire markings. Installation of a lighting network and supplying power to sockets requires the use of a cable with three wires.
The use of this color system significantly reduces the time for repairs, connecting sockets, etc. This scheme also minimizes the qualification requirements for the installer. This means that almost any adult man is able to carry out, for example, installation of a lamp himself.
In this article we will look at how grounding, zero and phase are designated. As well as other color markings of wires.
Ground color
The color of the grounding wire, “earth” - almost always indicated in yellow-green color, windings that are either completely yellow or light green are less common. The wire may be marked "PE". You can also find green-yellow wires marked “PEN” and with blue braiding at the ends of the wire at the fastening points - this is grounding combined with neutral.
In the distribution panel (DP) it should be connected to the grounding bus, to the housing and the metal door of the panel. Concerning distribution box, then the connection goes to the grounding wires from the lamps and from the grounding contacts of the sockets. The “ground” wire does not need to be connected to the RCD (residual current device), therefore RCDs are installed in houses and apartments, since electrical wiring is usually carried out with only two wires. Grounding designation on the diagrams:
Conventional ground(1) Clean ground(2) Safety ground(3) Chassis ground(4) DC ground(5)
Color of zero, neutral
The “zero” wire must be of blue color. In the distribution board it must be connected to the zero bus, which is designated by the Latin letter N. All blue wires must be connected to it. The bus is connected to the input via a counter or directly, without additional installation machine. In the distribution box, all wires (except for the wire from the switch) of blue color (neutral) are connected and do not participate in switching. To the sockets, the blue “zero” wires are connected to the contact, which is designated by the letter N, which is marked on the back of the sockets.
Phase color
The designation of the phase wire is not so clear. It can be either brown, or black, or red, or other colors except blue, green and yellow. In an apartment switchboard, the phase wire coming from the load consumer is connected to the lower contact of the circuit breaker or to the RCD. In switches, the phase wire is switched; during switching off, the contact closes and voltage is supplied to consumers. In phase sockets, the black wire must be connected to the contact marked with the letter L.
How to find ground, neutral and phase in the absence of a designation
If there is no color marking of the wires, then it is possible to determine the phase; upon contact with it, the screwdriver indicator will light up, but not on the neutral and ground wires. You can use a multimeter to find ground and neutral. We find the phase with a screwdriver, fix one contact of the multimeter on it and “probe” the wires with another contact; if the multimeter shows 220 volts, this is neutral; if the values are below 220, then it is grounding.Letter and numeric wire markings
The first letter “A” denotes aluminum as the core material; in the absence of this letter, the core is copper.
The letters "AA" denote a multi-core cable with an aluminum core and an additional braid made of it.
"AC" is indicated in case of additional lead braiding.
The letter “B” is present if the cable is waterproof and has an additional double-layer steel braid.
"BN" cable braid does not support combustion.
"B" polyvinyl chloride shell.
"G" does not have a protective shell.
"g" (lowercase) bare waterproof.
"K" is a control cable wrapped with wire under the top sheath.
"R" rubber casing.
"NR" non-flammable rubber casing.
Wire colors abroad
The color marking of wires in Ukraine, Russia, Belarus, Singapore, Kazakhstan, China, Hong Kong and the countries of the European Union is the same: Ground wire - Green-yellow
Neutral wire - blue
phases are marked with different colors
The neutral designation is black in South Africa, India, Pakistan, England, but this is the case with old wiring.
Currently the neutral is blue.
In Australia it can be blue and black.
In the USA and Canada it is designated white. You can also find gray labeling in the USA.
The ground wire is yellow, green, yellow-green in color everywhere, and in some countries it may also be without insulation.
Other wire colors are used for phases and may be different, except for the colors indicating other wires.