Any electric cable for ease of installation is made with multi-colored insulation on the cores. When installing standard wiring, three-core cables (phase, zero, ground) are usually used.
Phase ("L", "Line")
The main conductor in the cable is always the phase. By itself, the word "phase" means "live wire", "active wire" and "line". Most often it is strictly certain colors. In the switchboard, the phase wire, before going to the consumer, is connected through a residual current device (RCD, fuse), the phase is switched in it. Attention! Jokes are bad with the bare phase, therefore, 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 is 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 it with a sting to a bare conductor, you can always find out whether it is a phase or not by the characteristic glow of the indicator. And it is better to immediately contact a qualified specialist.
Zero ("N", "Neutre", "Neutral", "Neutral" "Null")
The second important wire is zero, popularly known as the "wire without current", "passive wire" and "neutral". He only happens blue. In apartment switchboards, it must be connected to the zero bus, it is marked with the symbol "N". To the socket, the zero wire is connected to the contacts, also marked with the sign "N".
Ground ("G", "T", "Terre" "Ground", "gnd" and "Earth")
Ground wire insulation is only yellow color with a green stripe. In the switchboard, it is connected to the ground bus, to the door and the shield body. In sockets, grounding is connected to the contacts marked with the Latin symbol "G" or with a sign in the form of an inverted and briefly underlined letter "T". Usually, ground contacts are visible and can protrude from sockets, becoming accessible to children, which sometimes shocks many parents, however, these contacts are not dangerous, although sticking fingers there is still not recommended. 
Attention! When working with electrical networks under voltage, there is always a high probability of human injury. electric shock or fire. Even if an RCD is installed, it is strongly recommended to observe all safety precautions! It is known that the special design of such a switch checks the synchronism of the phase and zero, and if the RCD detects a phase current leakage without returning some of its percentages 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. 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), moreover, which phase comes to the apartment for us, for further consideration of the material, is deeply indifferent. Since this example is very schematic, the physical meaning of such a connection should be briefly considered (Figure 2).
An electric current arises in the presence of a closed electrical circuit, which consists of a winding (Lt) of a substation transformer (1), a connecting line (2), and the electrical wiring of our apartment (3). (Here the designation of the phase is L, zero is N).
Another point is that in order for current to flow through this circuit, at least one consumer of electricity Rn 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 winding Lt at the substation is grounded, that is, it has electrical contact with the ground (Zml). The wire that comes from this point is zero, the other is phase.
This implies another obvious practical conclusion: the voltage between "zero" and "ground" will be close to zero (determined by the ground resistance), and "ground" - "phase", in our case 220 Volts.
Moreover, if hypothetically ( In practice, this cannot be done!) ground the neutral wire in the apartment by disconnecting it from the substation (Fig. 3), the voltage "phase" - "zero" we will have the same 220 Volts.
What is phase and zero figured out. Let's talk about grounding. The physical meaning of it, I think, is already clear, so I propose to look at it from a practical point of view.
If for some reason an electrical contact occurs between the phase and the conductive (metal, for example) body of the electrical appliance, voltage appears on the latter.
When this body is touched, an electric current can 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 (damp or metal floor, direct contact building structure with natural grounding conductors (heating batteries, metal water pipes) the more danger you face.
The solution to this problem is to ground the case (Figure 5), while the dangerous current "leaves" through the ground circuit.
Structurally, the implementation of this method of protection against electric shock for apartments, office space consists in laying a separate grounding conductor PE (Fig. 6), which is subsequently grounded in one way or another.
How this is done is a topic for a separate conversation, for example, in a private house you can make a ground loop yourself. Exist various options with its 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 DEFINE PHASE AND ZERO
Where is the phase, where is zero - a question that arises when connecting any electrical device.
To begin with, let's look at how to find phase. The easiest way to do this is with an indicator screwdriver (Figure 7).
With a conductive tip of the indicator screwdriver (1) we touch the controlled section of the electrical circuit (during operation, the contact of this part of the screwdriver with the body is unacceptable!), Touch the contact pad 3 with the finger of the hand, the glow of the indicator 2 indicates the presence of a phase.
In addition to the indicator screwdriver, the phase can be checked with a multimeter (tester), although this is more laborious. To do this, the multimeter should be switched to the 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 measured circuit, with the other - the natural ground electrode (heating batteries, metal water pipes). With the readings of the multimeter corresponding to the mains voltage (about 220 V), there is a phase on the measured section of the circuit (diagram Fig. 8).
I draw your attention - if the measurements taken show the absence of a phase, it is impossible to assert that this is zero. An example is in Figure 9.
- Now there is no phase 1 at the point.
- When switch S is closed, it appears.
Therefore, you should check all possible options.
I want to note that if there is a ground wire in the electrical wiring, distinguish it from the neutral conductor by the method electrical measurements within the apartment is not possible. As a rule, the wire that is used for grounding has a 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 marking of mounting wires. It is a designation in electrics L and N. Due to a strictly defined color, the master can quickly determine which of the wires is phase, zero or ground. This is important when connecting or disconnecting equipment from the power supply.
Types of wires
When connecting electrical equipment, installing various systems, one cannot do without special conductors. They are made from aluminum or copper. These materials are excellent conductors of electricity.
Zero conductors
These wires fall into three categories:
- zero working conductors.
- zero protective (earth) conductors.
- zero conductors, combining a protective and working function.
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". Zero conductors of cables have the following color:
- blue color throughout its length without additional inclusions;
- Blue colour along the entire length of the core without additional inclusions.
What does L, N and PE mean in electrical? 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, has a color designation in electrics (L and N). The wires are colored blue, with yellow-green stripes at the ends and connections.
The need to check labeling
Designation LO, L, N in the electrician during installation electrical networks - important detail. How to check the correct color coding? To do this, you need to use an indicator screwdriver.
To determine which of the conductors is phase and which is zero using an indicator screwdriver, you need to touch it with a sting to the uninsulated part of the wire. If the LED lights up, then a phase conductor has been touched. After touching the neutral wire with a screwdriver, there will be no luminous effect.
The importance of the color marking of conductors and strict adherence to the rules for its use will significantly reduce the time installation work and troubleshooting electrical equipment, while ignoring these elementary requirements turns into a health risk.
When working with electrical wiring, and especially in a switchboard, you need to clearly know which of the wires is responsible for what. Therefore, there is color coding, which allows, without the use of special devices, to determine which of the wires is a phase, zero, or serves as a ground.
General marking rules have been developed and described in the rules for the installation of electrical installations (edition 7).
Important! 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 not the right 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 designate zero (N); (Fig. 1)
- yellow or green, as well as their combination - indicate the ground (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 phases of the wires (L). (Fig. 4)
In no case should wires of similar colors be used in one connection. So the situation will be unacceptable as a result of which, for example, yellow or green wires will be used in the shield and at the same time there will be a yellow-green color, which will indicate the protection wire.
Should know! On wires that are covered with insulation, the combination of colors of green and yellow should be such that on a section 1.5 centimeters long, one color has at least thirty percent, but not more than seventy of the surface, and the second color has the entire remaining part.
When the neutral wire is in the circuit, it should have a blue color, and to avoid confusion, there should not be any similar ones. But if there is no zero, then the color can be used, but not to designate a protective cable.
The designation of the wires must be carried out using color shades, numbers, letters or their various combinations.
Necessarily! Numerical designations must be made in Arabic, alphabetic - in Latin.
If it is not possible to use wires with insulation of the desired color already applied to them, or they will not be insulated, then it is still necessary to designate them without fail. 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 letter and number designations.
Many can now look into their switchboards and find there a discrepancy between the color codes that currently exist. But do not assume that this is not correct. It’s just that earlier GOST acted for such cases, which regulated all installations. Therefore, it makes no sense to change the phase and zero markings now.
Important! If there is no confidence in the correct identification of the wires, then you should resort to using phase detection using a tester.
It is 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 color coding of wires and cables is needed
Installation and maintenance work in electrical installations is not only about reliability, but also about safety. Full 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, zero and earth.
According to the PUE, the following colors of current-carrying conductors are allowed:
- red;
- brown;
- black;
- gray;
- white;
- pink;
- orange;
- turquoise;
- purple.
The list below contains many wire color options, but there are not several colors that are used only to designate neutral and protective wires:
- blue color and its shades - working neutral wire (neutral - N);
- yellow with green stripe - protective earth (PE);
- yellow-green insulation with blue marks on the ends of the cores - combined (PEN) conductor.
It is allowed to use conductors with green insulation with a yellow stripe for grounding, and for combined conductors of blue insulation with yellow-green marks at the ends.
The colors must be the same in each circuit within the same device. Branch circuits must be carried out with the same colored conductors. The use of insulation without differences in shades indicates a high installation culture and greatly facilitates further maintenance and repair of equipment.
Phase color
In cases where the installation of the electrical installation is carried out using rigid metal tires, 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 - ground bus.
The color of the phases must be preserved within the entire device, but not necessarily on the entire surface of the tire. It is allowed to mark the phase designation only at the connection points. On the painted surface, you can duplicate the color with the symbols “GZK” for the paint of the corresponding colors.
If the tires are not available for inspection or work when voltage is present on them, then it is allowed not to paint them.
The color of the phase wires connected to the rigid busbars may not match them in color, since the difference in the accepted designation systems for flexible conductors and rigid stationary distribution busbars is visible.
Neutral color
What color is the neutral wire, stipulate GOST standards, so when looking at the installation of the power plant, the question should not arise, blue wire- this is a phase or zero, since the blue color and its shades (blue) are taken to indicate the neutral (working ground).
Other neutral core colors are not permitted.
The only acceptable use of blue and blue insulation is the designation of a negative pole or midpoint in circuits direct current. You can't use this color anywhere else.
Ground wire color code
Regulations specify what color the earth wire is in electrical installations. This is a yellow-green wire, the color of which stands out well from the rest of the wires. It is allowed to use wire with yellow insulation and a green stripe on it, or it can be green insulation with a yellow stripe. No other color of ground wire is permitted, nor are green/yellow conductors permitted to be used in circuits where voltage is present or may be energized.
The listed marking rules are observed in the countries of the post-Soviet space and in the EU countries. 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 earth - yellow or green.
The standards of a number of countries allow the use of bare metal without insulation as a protective ground.
Ground wires are switched on prefabricated non-insulated terminals and interconnect all metal parts of the structure that do not have reliable electrical contact with each other.
Coloring in the network 220V and 380V
Installation of one- and three-phase electrical networks is facilitated if the wiring is made with multi-colored wire. Previously, flat two-core wire was used for single-phase apartment wiring. white color. During installation and repair, in order to eliminate errors, it was necessary to ring each core separately.
The release of cable products with colored cores in different colors reduces the complexity of the work. To designate 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 marking 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 core color standard, so a multi-phase cable contains differently colored cores, where the phase is white, red and black, zero is blue, and the ground is yellow-green conductors.
When servicing networks mounted according to modern standards, you can accurately determine the purpose of the wires in junction boxes. If there is a bundle of multi-colored wires, the brown one will necessarily be phase. The neutral wire in the distribution boxes has no branches and breaks. The exception is taps to multi-pole switching devices with a complete opening of the circuit.
Coloring in DC networks
For DC networks, it is customary to mark the conductors connected to the positive pole in red, to the negative - in black or blue. In bipolar circuits, blue-tinted insulation is used when marking the midpoint (zero) of the power supply.
There are no standards for color markings in multi-voltage circuits. What color are the plus and minus wires, what voltage is in them - this can only be determined by decoding 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 a positive voltage of the on-board network are red or its shades (pink, orange), and those connected to ground are black. The rest of the wires have a specific color, which is determined by the car manufacturer.
Letter designation of wires
Color marking can be supplemented with letters. Partially, the symbols for designation are standardized:
- L (from the word Line) - phase wire;
- N (from the word Neutral) - neutral wire;
- PE (from a combination of Protective Earthing) - grounding;
- “+” – positive pole;
- “-” – negative pole;
- M - middle point in DC circuits with bipolar power supply.
To designate the protective earth connection terminals, a special symbol is used, which is stamped on the terminal or on the instrument case in the form of a sticker. The ground symbol is the same for most countries in the world, which reduces the likelihood of confusion.
In multi-phase networks, the symbols are supplemented by the phase serial number:
- L1 is the first phase;
- L2 - second phase;
- L3 is the third phase.
There is marking according to old standards, when the phases are denoted by the symbols A, B and C.
A deviation from the standards is the combined phase designation system:
- La is the first phase;
- Lb is the second phase;
- Lc is the third phase.
In complex devices, there may be additional designations characterizing the name or number of the circuit. It is important that the markings of the conductors match throughout the entire circuit where they participate.
Letter designations are applied with indelible, clearly visible paint on the insulation near the ends of the cores, on pieces of PVC insulation or a heat-shrinkable tube.
Connection terminals may have printed signs that indicate the circuits and polarities of the power supply. Such signs are made by paint, stamping or etching, depending on the material used.
