For ease of installation, any electrical cable is made with multi-colored insulation on the cores. When installing standard electrical wiring, three-core cables are usually used (phase, neutral, ground).
Phase ("L", "Line")
The main wire in the cable is always the phase. The word "phase" itself means "live wire", "active wire" and "line". Most often he is strictly certain colors. In the distribution panel, the phase wire, before going to the consumer, is connected through a residual current device (RCD, fuse), and phase switching occurs in it. Attention! The bare phase is no joke, so in order not to confuse the phase with anything else, remember: the phase contacts are always marked with the Latin symbol “L”, and the phase wire can be red, brown, white or black! If you are not sure about this or the wiring is arranged differently, then purchase a screwdriver with a simple phase indicator. By touching the bare conductor with its tip, you can always find out whether it is a phase or not by the characteristic glow of the indicator. It’s better to immediately contact a qualified specialist.
Zero ("N", "Neutre", "Neutral", "Neutral" "Zero")
The second important wire is the neutral, popularly known as the “wire without current”, “passive wire” and “neutral”. It only happens blue. In apartment distribution panels it must be connected to the zero bus, it is marked with the symbol “N”. At the socket, the neutral wire is connected to the contacts, also marked with the sign “N”.
Ground ("G", "T", "Terre" "Ground", "gnd" and "Earth")
Ground wire insulation can only be yellow color with a green stripe. In the distribution panel it is connected to the grounding bus, to the door and body of the panel. In sockets, grounding is connected to contacts marked with the Latin symbol “G” or with a sign in the form of an inverted and briefly underlined letter “T”. Typically, grounding contacts are visible and can protrude from sockets, becoming accessible to children, which sometimes causes shock to many parents; however, these contacts are not dangerous, although sticking your fingers there is still not recommended. 
Attention! When working with live electrical networks, there is always a high probability of injury to a person. electric shock or fire. Even if an RCD is installed, it is strongly recommended to follow all safety precautions! It is known that the special design of such a switch checks the synchronism of the phase and zero operation, and if the RCD detects a phase current leak without returning some of its percent to zero, it will immediately break the contact, which will save a person’s life; however, if you touch not only the phase, but also zero, then the RCD will not save you. Touching both wires is deadly!!!
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 in the presence of a closed 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 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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World manufacturers household appliances When assembling their equipment, they use color coding for the mounting wires. It represents the designation in electrics L and N. Thanks to a strictly defined color, the master can quickly determine which of the wires is phase, neutral or ground. This is important when connecting or disconnecting equipment from power.
Types of wires
When connecting electrical equipment and installing various systems, you cannot do without special conductors. They are made of aluminum or copper. These materials conduct electricity well.
Neutral conductors
These electrical wires are divided into three categories:
- zero working conductors.
- neutral protective (ground) conductors.
- neutral conductors, combining protective and working functions.
What is the designation of wires in electrics L and N? Network neutral or zero working conductor in circuits electrical circuits denoted by the Latin letter “N”. The neutral conductors of the cables are colored as follows:
- blue color throughout its entire length without additional inclusions;
- Blue colour along the entire length of the core without additional inclusions.
What do L, N and PE mean in electrical engineering? PE (N-RE) - zero protective conductor, which along the entire length of the wire entering the cable is painted with alternating lines of yellow and green.
The third category of neutral conductors (REN-wires), which combine working and protective functions, have a color designation in electrical engineering (L and N). The wires are painted blue, with ends and connections with yellow-green stripes.
The need to check the labeling
Designation LO, L, N in electrics during installation electrical networks - important detail. How can I check if the color coding is correct? To do this you need to use an indicator screwdriver.
To determine which of the conductors is phase and which is neutral using an indicator screwdriver, you need to touch the uninsulated part of the wire with its tip. If the LED lights up, it means that a phase conductor has been touched. After touching the neutral wire with a screwdriver, there will be no glowing effect.
The importance of color marking of conductors and strict adherence to the rules of its use will significantly reduce the time of conducting installation work and troubleshooting electrical equipment, while ignoring these basic requirements results in a health risk.
When working with electrical wiring, and especially in a switchboard, you need to clearly know which wire is responsible for what. Therefore there is color coding, which allows, without the use of special instruments, to determine which of the wires is phase, neutral or serves for grounding.
General marking rules have been developed and described in the electrical installation rules (edition 7).
Important! The PUE is mandatory for execution in any case.
You can also often hear that the colors of the plus and minus wires do not matter. But this is fundamentally the wrong position, which can lead to tragic consequences.
And so, according to the requirements, the color designations for phase and zero, as well as protection, should be as follows:
- blue color – serves to indicate zero (N); (Fig. 1)
- yellow or green, as well as their combination - indicate the grounding (protection) wire (PE); (Fig. 2)
- combination of yellow-green and blue - serves to indicate the combined zero (working) and ground (PEN); (Fig. 3)
- brown, red, black, gray, purple, pink, white, turquoise, orange - they all indicate the color of the wire phases (L). (Fig. 4)
In no case should wires of similar colors be used in one connection. So, it would be unacceptable for a situation to result in which, for example, yellow or green wires would be used in the shield and at the same time there would be a yellow-green color that would indicate the protection wire.
You should know! On wires that are covered with insulation, the combination of colors green and yellow should be such that in a section 1.5 centimeters long, one color has at least thirty percent, but no more than seventy percent of the surface, and the second color has the entire remaining part.
When there is a neutral wire in the circuit, it should have a blue color, and to avoid confusion, there should not be similar ones. But if zero is missing, then the color can be used, but not to indicate the protective cable.
Wire identification must be done using color shades, numbers, letter designations or their various combinations.
Necessarily! Numerical designations must be made in Arabic, alphabetic ones in Latin.
If it is not possible to use wires with insulation of the required color already applied to them, or they are not insulated, then it is still necessary to mark them. So often for this you can use multi-colored insulating tape, which must be glued to the ends of the sections of wires that are connected to various devices or elements. Also on these ends, you can hang tags with alphabetic and numerical designations.
Many people can now look at their switchboards and find a discrepancy between the current color designations. But don’t think that this is wrong. It’s just that previously, for such cases, GOST was in force, which regulated all installations. Therefore, there is no point in changing the phase and zero markings now.
Important! If you are not sure of the correct identification of wires, then you should resort to using phase determination using a tester.
Important for faster and correct installation of electrical distribution devices, ease of repair and elimination of errors. The colors of wires in electrics are regulated by regulatory documents (PUE and GOST R 50462-2009).
Why do we need color coding for wires and cables?
Installation and maintenance work in electrical installations is associated not only with ensuring reliability, but also safety. Complete error elimination is required. For these purposes, a system of color designations for core insulation has been developed, which determines what color the wires are phase, neutral and ground.
According to the PUE, the following colors of current-carrying conductors are allowed:
- red;
- brown;
- black;
- gray;
- white;
- pink;
- orange;
- turquoise;
- purple.
The above list contains many options for wire colors, but there are not several colors that are used only to indicate neutral and protective wires:
- blue color and its shades – working neutral wire (neutral – N);
- yellow with a green stripe – protective earth (PE);
- yellow-green insulation with blue marks at the ends of the conductors - combined (PEN) conductor.
It is allowed to use conductors with green insulation with a yellow stripe for grounding, and for combined conductors blue insulation with yellow-green marks at the ends.
The color must be the same in each circuit within one device. Branch circuits must be made with identically colored conductors. The use of insulation without differences in shades indicates a high standard of installation and greatly facilitates further maintenance and repair of equipment.
Coloring phase
In cases where the electrical installation is installed using rigid metal busbars, the tires are painted with indelible paint in the following colors:
- yellow – phase A (L1);
- green – phase B(L2);
- red – phase C (L3);
- blue – zero bus;
- longitudinal or inclined stripes of yellow and green color – grounding bus.
The color of the phases must be maintained throughout the entire device, but not necessarily over the entire surface of the bus. It is allowed to mark the phase designation only at the connection points. On a painted surface, you can duplicate the color with the “ZhZK” symbols for paint of the corresponding colors.
If tires are not accessible for inspection or work when there is voltage on them, then they may not be painted.
The color of phase wires connected to rigid busbars may not coincide with them in color, since there is a difference in the accepted designation systems for flexible conductors and rigid stationary distribution busbars.
Neutral color
What color the neutral wire is is specified by GOST standards, so when looking at the installation of a power plant, the question should not arise: blue wire- this is phase or zero, since the blue color and its shades (blue) are accepted to indicate neutral (working grounding).
Other colors of neutral cores are not permitted.
The only acceptable option is to use blue and cyan insulation to indicate the negative pole or midpoint in circuits direct current. This color cannot be used anywhere else.
Ground wire color coding
The rules indicate what color the ground wire in electrical installations is. This is a yellow-green wire, the color of which stands out well against the background of the other wires. It is acceptable to use a wire with yellow insulation and a green stripe on it, or it can be green insulation with a yellow stripe. It is not allowed to use any other color of the ground wire, just as it is not allowed to use green-yellow conductors for installing circuits on which voltage is present or may be applied.
The listed labeling rules are observed in the countries of the post-Soviet space and in the countries of the European Union. Other states mark the cores in a different way, which can be seen on imported equipment.
Basic colors for marking abroad:
- neutral – white, gray or black;
- protective grounding – yellow or green.
Standards in a number of countries allow the use of bare metal without insulation as protective grounding.
Grounding wires are switched on prefabricated non-insulated terminals and connect to each other all metal parts of the structure that do not have reliable electrical contact with each other.
Colors for 220V and 380V networks
Installation of single- and three-phase electrical networks is facilitated if the wiring is made with multi-color wire. Previously, a flat two-core wire was used for single-phase residential wiring white. During installation and repair, to eliminate errors, it was necessary to ring each core individually.
The production of cable products with colored cores in different colors reduces the labor intensity of the work. To indicate phase and zero in single-phase wiring, it is customary to use the following colors:
- red, brown or black – phase wire;
- other colors (preferably blue) – neutral wire.
Phase markings in three-phase network slightly different:
- red (brown) – 1 phase;
- black – 2 phase;
- gray (white) – 3 phase;
- blue (cyan) – working zero (neutral)
- yellow-green – grounding.
Domestic cable products comply with the standard for core coloring, so a multiphase cable contains differently colored cores, where the phase is white, red and black, the neutral is blue, and the ground is yellow-green conductors.
When servicing networks installed according to modern standards, you can accurately determine the purpose of the wires in distribution boxes. If there is a bundle of multi-colored wires, the brown one will definitely be phase. The neutral wire in the distribution boxes has no branches or breaks. The exception is branches to multi-pole switching devices with complete circuit breaking.
Coloring in DC networks
For DC networks, it is customary to mark conductors connected to the positive pole in red, and to the negative pole in black or blue. In bipolar circuits, blue insulation is used to mark the midpoint (zero) of the power supply.
There are no standards for color codes on multi-voltage circuits. What color are the plus and minus wires, what voltage is in them - this can only be determined by the decoding of the device manufacturer, which is often given in the documentation or on one of the walls of the structure. Example: computer power supply or car wiring.
Automotive wiring is characterized by the fact that in it the circuits with positive voltage of the on-board network are red or its shades (pink, orange), and those connected to ground are black. The remaining wires have a specific color, which is determined by the car manufacturer.
Letter designation of wires
Color markings can be supplemented by letters. Partially the symbols for the designation are standardized:
- L (from the word Line) – phase wire;
- N (from the word Neutral) – neutral wire;
- PE (from the combination Protective Earthing) - grounding;
- “+” – positive pole;
- “-” – negative pole;
- M – midpoint in DC circuits with bipolar power supply.
To designate the protective grounding connection terminals, a special symbol is used, which is stamped on the terminal or on the device body in the form of a sticker. The grounding symbol is the same for most countries in the world, which reduces the likelihood of confusion.
In multiphase networks, the symbols are supplemented by the serial number of the phase:
- L1 – first phase;
- L2 – second phase;
- L3 – third phase.
There is marking according to old standards, when the phases are designated by the symbols A, B and C.
A deviation from the standards is the combined phase designation system:
- La – first phase;
- Lb – second phase;
- Lc – third phase.
In complex devices, additional symbols may be found that characterize the name or number of the circuit. It is important that the markings of the conductors match throughout the entire circuit where they are involved.
Letter designations are applied with indelible, clearly visible paint on the insulation near the ends of the cores, on sections of PVC insulation or heat-shrinkable tube.
Connection terminals may have marks that indicate circuits and power polarities. Such signs are made by painting, stamping or etching, depending on the material used.
