What is color coding of buses and wires and why is it needed? Wire color coding

Carrying out electrical installation work is almost impossible without the presence of cables with insulation of different shades. This is not a manufacturer’s advertising gimmick or a fashion trend, but a necessity for professional electricians.

According to the requirements, the color of the wires: phase zero earth must be different from each other and have a corresponding option.

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Concepts of phase, neutral and grounding

To answer the question: “Phase, neutral, ground - what is it?”, you need to understand how the wiring in the house is connected. Electricity enters the home from a transformer distributor. Zero is a wire connected to the ground loop at the substation. It is needed to create a load on the phase that is connected to the other end of the transformer winding. Grounding is not included in the power supply; it provides protection in the event of a fault.

The use of insulation of different shades makes it possible to determine whether the wires belong to a certain group.

In addition, this eliminates errors during electrical installation, which will protect against short circuits and electric shocks during network repairs.

The choice of wire colors in a three-core cable occurs according to a single standard.

The cores have letter and color designations. Most often, insulation of a certain shade of the entire wire is used; sometimes you can specify a certain color on the connections and its ends.

This is done using multi-colored electrical tape or a special tube. To do everything correctly, you need to know how phase and zero are designated.

Varieties of insulation shades

To make it convenient for electricians to work and not have to constantly check where the phase is and where– zero using special testers, and some rules have been adopted for the designation of phase and zero (PUE).

How do phase wires differ in color?

According to the accepted standard, phase cores come in the following shades:

• red;
• black;
• grey;
• brown;
• pink;
• white;
• orange;
• violet.

Important! Wires, which are marked with the letters L, N, in electrics refer to phase and zero, respectively, the protection core is signed PE.

If a single-phase network is a branch of a three-phase circuit, then the color of the core insulation must be the same as that of the conductor to which it is connected.

An important point is that the color of the phase designation must not match the tone of ground and zero.

Attention! If a cable that does not have markings is used, multi-colored marks are placed on it at the joints and at the ends.

It is advisable to use the same cable when laying wiring throughout the apartment so that the colors of the electrical wires are the same everywhere.

Color of working zero and grounding

The color of the neutral wire is usually blue, and the protective grounding conductor is made of yellow-green color with stripes that are applied longitudinally or transversely. If the functions of the neutral and protective conductor are combined, then its color is blue with yellow-green stripes at the joints.

If you do not know what color the phase is, in order to determine whether the conductors are connected correctly, you need to determine the phase and neutral wires: this will require special tools.

This is the simplest option for finding the phase. Without an indicator screwdriver, you should not begin replacing lamps or installing switches or sockets.

Working with the tool is very simple. You need to touch the wire with a screwdriver, and if it is energized, then when you press the contact on the back of the tool, the lamp will light up.

A light signal indicates that a phase has been detected. This is the simplest and most often recommended method for locating a phase wire by electricians. The cost of a screwdriver is low, so anyone can afford to have one. However, it has its drawbacks, for example, it can show tension where there is none.

The multimeter does not have a separate special mode that will help determine phase or zero: this can only be determined by the presence of numbers on the display or their absence.

When measuring the mains voltage with a tester, you need to select a mode to determine the current voltage in an alternating network. Before you begin determining the phase, test the device on any working outlet. After this, you can look for the phase with the red probe. If, having installed it on the phase, you begin to touch the remaining wires with another probe, you will find zero (the device will show 220V) or ground.

But it will be difficult to establish where the grounding is and where the zero is. If you need to do this, then you should disconnect the grounding wire at the electrical panel, then when checking with the device it will not show 220V on this conductor.

Modern industry produces multimeters of two types: analog and digital. Each of them has its own advantages and disadvantages.

For example, analog instruments can help make measurements in conditions of interference and waves. The digital device is used more often; it is used by construction organizations and manufacturers of radio equipment.

Digital models of appliances are also more often present in everyday life.

If we talk about the technical characteristics of a multimeter, digital models have more accurate measurement readings, but they differ significantly in cost, which depends on the built-in functions of the equipment. The indicator can be digital or pointer, the latter is considered more accurate. There are options that can be connected to a computer to transfer data.

Attention! In order for the device to serve for a long time, you should pay attention to its manufacture. The housing must be protected from shock and moisture penetration. It is better if the kit includes a special case for storing and carrying equipment.

If the rules for color marking of wires were not used when creating the electrical wiring in the house, then it is difficult for other electricians to work with such a network. It will be necessary to check the phase and zero only with the help of special instruments.

If, when installing a network, it is not possible to purchase cores of the appropriate shades, then you can mark the connections with colored electrical tape. This is allowed by the rules. In addition, during installation you should adhere to the following recommendations:

• It is worth choosing cables from the same manufacturer: in this case, the colors of the cores will be identical, this will eliminate errors when working with them;
• If you still had to use products from different manufacturers or different shades, then it is worth marking the wires with electrical tape of the corresponding colors. Do not rely on memory, so as not to guess later whether the blue wire is a phase or a neutral.
• If you had to extend the cable, take wires with the same color options as on the main one.
• Do not use cables without grounding (yellow-green core).

By applying these simple tips, you can avoid mistakes when creating electrical wiring or repairing it. This will keep you out of trouble. If another electrician has to service or repair the network, he will quickly figure it out and will not have to check each wire with instruments.

Nowadays it is impossible to imagine installing electrical wiring without using various wire colors(colored conductor insulation). Color coding of wires is not some kind of marketing ploy to attract customers or decorate products.

In fact, different colors of wires are an urgent need, since marking the wires helps to know the purpose of each of them in a certain group for easier switching. Also, when isolated, the risk of errors during the installation of wires is greatly reduced, and, accordingly, the occurrence of a short circuit during a test run or electric shock during repair and maintenance work of networks.

The colors chosen for marking conductors are specially selected and supervised by uniform PUE standards. These standards specify that conductor cores should be distinguished by alphanumeric or color codes.

This article will talk specifically about the meaning of wire color. It is worth noting that the work of switching conductors has been significantly simplified after the adoption of uniform color identification standards. Each core with a specific purpose is now marked with a unique color, for example: blue, yellow, brown, gray, etc.

Often color markings are applied along the entire length of the conductor, but identification at connection points or at the ends of the conductors is also acceptable; this is why cambrics (colored heat-shrinkable tubing) or electrical tape of different colors are used. In order to avoid unnecessary work such as applying marks using tubes or electrical tape, it is enough to correctly determine the color marking of the insulation when purchasing. You should also purchase it in the right quantity to ensure the same marking of wiring throughout the apartment or throughout the house.

Below we will discuss how wire color changesin DC, single-phase and three-phase current networks.

Colors of busbars and wires for three-phase alternating current.

At power plants and substations in three-phase networks, high-voltage wires and buses are painted as follows: phase “A” - yellow; phase “B” is green, and phase “C” is red.

What are the colors of the “+” and “-” wires in a DC network:

In addition to AC networks, DC circuits are also widely used. DC circuits are used in:

1. In construction, when using forklifts, electric trolleys and electric cranes, as well as in industry.

2. In electric transport - trams, trolleybuses, electric locomotives, motor ships, etc.

3. At electrical substations - to supply automation with energy.

In a DC network, only 2 wires are used, since in such networks there is no phase or neutral conductor, and there are only positive and negative buses (+ and -).

According to regulatory documents, wires and tires with a positive charge (+) are painted red, and wires and tires with a negative charge (-) are marked blue. The blue color indicates the middle conductor (M).

The positive conductor of a two-wire network is marked with the same color as the positive conductor of a three-wire network to which it is connected only if the two-wire DC network is created through a branch from a three-wire DC network.

Wire color in electrical wiring: ground, phase and zero.

To eliminate confusion and simplify installation work when laying AC electrical networks, use multi-core wires in multi-colored insulation.

Wire color code It is especially important when wiring is done by one person, and maintenance or repairs by another. Otherwise, he will have to constantly check where the phase is and where the zero is using a probe. Those who have worked with old wiring know how annoying it can be, because previously there was only white or black insulation in everyday life. Since Soviet times, the color designation of wires has constantly changed until a special standard was defined. Now each conductor color determines its purpose in the wire.

Currently, the regulatory document is PUE 7, which regulates the color marking of insulated or non-insulated conductors, where, in accordance with GOST R 50462 “Identification of conductors by colors or digital designations,” only certain symbols and colors should be used.

The main purpose of marking electrical wiring is to easily and quickly determine the purpose of the conductor along its entire length, which is actually one of the main requirements of the PUE standards.

Below we will consider what color conductors should be for electrical installations of alternating current, voltage up to 1000V and with a fully grounded neutral (for example, wiring of administrative buildings or residential buildings).

Colors of the zero working and zero protective conductor.

Neutral working conductors (N) are indicated in blue. The neutral protective conductor (PE) is marked with yellow-green transverse or longitudinal stripes. This combination must be used exclusively for marking grounding conductors.

Combined neutral working and neutral protective conductors (PEN) - blue color along the entire length of the cord with yellow-green stripes at the junctions or at the ends. It is important to mention that GOST today allows the reverse color option, that is, yellow-green stripes with blue at the junction points.

To summarize, then wire color should be distributed like this:

1. Combined (PEN) - yellow-green with blue marks at the ends;

2. Zero worker (N) - light blue (blue) color;

3. Zero protective (PE) - yellow-green.

Colors of phase wires.

According to the PUE, when marking phase conductors, preference should be given to the following colors: turquoise, black, orange, brown, white, red, pink, gray or purple.

It is known that a single-phase electrical circuit can be created by branching from a three-phase one; in this case, the color of the phase conductor of the single-phase circuit must match the color of the phase conductor of the three-phase circuit.

Color designation of conductor insulation coating must be carried out in such a way that the color of the phase conductor is easily distinguishable from the color of N, PE or PEN conductors. When using unmarked wire, colored identifiers are placed at the connection points or at the end.

There are, in fact, not many different types of conductors and their connections. In the electrical power industry, a distinction is made between supply and protective conductors. Some have heard words such as “neutral” and “phase” wire. However, this is where questions arise. How to determine zero and phase in a real network?

What kind of conductors are there in a socket?

You can understand the question “what is phase and zero” without delving into the jungle of clarifying the structure, advantages and negative aspects of three-phase or five-phase circuits. You can practically disassemble everything on your fingers by opening the most ordinary household outlet, which was installed in an apartment or private house ten to fifteen years ago. As you can see, this outlet connects to two wires. How to determine zero and phase?

How do the wires in a socket work and why are they needed?

As you can see, there are certain differences between workers and zeros. What is the symbol for phase and zero? A bluish or blue color is the color of the phase wire, while zero is indicated by any other colors, with the exception, of course, of blue colors. It can be yellow, green, black and striped. There is no current flowing. If you take it and do not touch the worker, then nothing will happen - there is no potential difference on it (in essence, the network is not ideal, and there may still be a small voltage, but it will be measured in millivolts at best). But this will not work with a phase conductor. Touching it may result in an electric shock, even fatal. This wire is always energized; current flows to it from generators and transformers and stations. You must always remember that under no circumstances should you touch the working conductor, since voltage of even a hundred volts can be fatal. And in the outlet it is two hundred and twenty.

How to determine zero and phase in this case? The socket, designed in accordance with European standards, contains three conductors at once. The first is phase, which is energized and painted in a variety of colors (with the exception of blue shades). The second is zero, which is absolutely safe to touch and is colored. But the third wire is called neutral protective. It is usually colored yellow or green. It is located in the sockets on the left, in the switches - at the bottom. The phase wire is located on the right and top, respectively. Given these colors and features, it is easy to determine where the phase is, where the zero is, and where the protective neutral wire is. But what is it for?

Why is a protective conductor needed in European sockets?

If the phase wire is intended to supply current to the socket, and the neutral wire is intended to lead to the source, then why do European standards regulate another wire? If the equipment that is connected is working properly, and all wiring is in working condition, then the protective zero will not take part, it is inactive. But if suddenly an overvoltage occurs somewhere, or a short circuit occurs on some parts of the devices, then the current enters places that are usually without its influence, that is, not connected to either a phase or a zero. A person will simply be able to feel the electric shock on himself. In the worst situation, you can even die from this, as the heart muscle can stop. This is where the protective neutral wire is needed. It "takes" the short circuit current and directs it to the ground or to the source. Such subtleties depend on the wiring design and the characteristics of the room. Therefore, you can safely touch the equipment - there will be no electric shock. The thing is that current always flows along the path of least resistance. In the human body, the value of this parameter is more than one kiloohm. The resistance of the protective conductor does not exceed a few tenths of one Ohm.

Determining the purpose of conductors

How to determine zero and phase? Any person has encountered these concepts in one way or another. Especially when you need to fix an outlet or do some wiring. Therefore, it is necessary to understand exactly where each conductor is. But how to determine zero and phase? It must be remembered that all manipulations of this kind with electricity are dangerous. Therefore, if you are unsure of your actions, it is better to contact a specialist. If you are already approaching the outlet and the wires in it, then you must first completely turn off the power to the entire apartment. At a minimum, this can save health and life. As mentioned earlier, usually the designation of phase and zero is done using coloring. With proper labeling, distinguishing them will not be difficult. Black (or brown) is the color of the phase wire; neutral usually has a bluish or bluish tint. If a European standard socket is installed, then the third (protective zero) is made in green or yellow. What to do if the wiring is one color? As a rule, in this case, at the ends of the wires there are usually special insulating tubes that have the necessary color markings. They are called "cambrics".

Identifying conductors using a special screwdriver

How to determine zero and phase? To do this, it is most convenient to buy a special indicator screwdriver. The handle of such a device is made of translucent or transparent plastic. There is a built-in diode - a luminous light bulb - inside. The top part of this screwdriver is metal. How to determine zero and phase using this method?

The procedure for performing measurements using an indicator screwdriver:

• de-energize the apartment;
• lightly strip the ends of the wires;
• we move them apart so as not to accidentally cause a short circuit by contacting the phase and zero;
• turn on the switch and supply current to the apartment;
• We take the screwdriver by the handle, which has a dielectric coating;
• place your finger (thumb or forefinger) on the contact, which is located on the back of the socket;
• touch the working end of the indicator to one exposed conductor;
• carefully observe the reaction of the screwdriver;
• if the diode lights up, then we can confidently state that;
• By method of elimination we understand that the remaining conductor is zero.

The indicator screwdriver reacts to the presence of voltage. Naturally, it is not in the neutral wire. However, there is a significant drawback of this method. Using an indicator screwdriver, it is impossible to understand how to determine: phase, zero, ground - where is what in the case of a European socket.

Method for determining phase and zero using a voltmeter

If the wires are not painted in the appropriate colors, and you don’t have an indicator screwdriver at hand, then you can go another way. We need a voltmeter (multimeter, tester). It is necessary to set it to the required range - over two hundred volts alternating current. How to determine the phase with a tester? We take one conductor that extends from the device (labeled V). We attach it to a previously de-energized conductor (any). Then we apply current (turn on the switch). And we simply record what the device display shows. After all of the above, turn off the power again and transfer the tester clamp to another conductor. If there is nothing on the display, this means that in front of us there is either a zero or a grounding protective neutral wire. However, you can use another method that answers the question: “How to determine zero and phase, as well as grounding.” To do this, we turn off the power to the apartment again and fix the V clamp on one of the wires. We also throw the second one onto any of the three conductors. The voltage turns on. If the arrow does not move, then you have chosen zero and protective. Accordingly, the voltage must be turned off again and the position of terminal V must be changed (place it on another previously unused conductor). We turn on the current again and take the appropriate measurements. Then we perform the same operation, but change the conductor again. Now you need to compare the results. If the first digit turned out to be larger, it means that we measured the voltage between the phase conductor (on which terminal V hung) and the zero one. Accordingly, the second wire will be a protective grounding wire. This method is based on measuring the potential difference.

Exotic ways to determine phase and zero in wiring

There are also “folk methods” that do not imply the presence of any special devices. They can be used only in the most extreme cases, since they are associated with an increased danger to health and life. For example, the potato method. To do this, put a freshly cut piece of potato on the previously de-energized conductors. It is necessary to prevent the wires from touching each other so that there is no short circuit between them. Then literally apply voltage for a couple of seconds and look at the potatoes. If one section near the wire turns blue, then a phase is connected to it.

Carrying out electrical installation work is a rather complicated task, which is best left to a specialist in this field. However, if you need to purchase various cables for installation, you need to understand their markings. The indication on the insulation of the products with an alphanumeric code is the marking of the wires.

At the moment, each manufacturer designates its products with codes so that any consumer, looking at it, can understand what the product is made of, what is the rated withstand voltage, the type of cross-section, as well as its design features and type of insulation.

To comply with these parameters, all factories and enterprises involved in the manufacture of electrical products are required to use the international standard - GOST. Marking the wires also allows you to easily determine the location of the phase, zero, and in some cases, ground. Let's look at the main electrical products on the market.

Cables

Electrical cables come in several types depending on the purpose of use. They may also consist of copper or aluminum strands, which are collected in bundles under one or different winding materials of plastic or PVC. There is also sometimes an additional protective shell made of steel tape.

Depending on the application, the color coding of the wires may also vary. So, they distinguish:

• RF cables that transmit radio and video signals.
• Controls for transmitting a signal to one or another device.
• Power cables are used in lighting fixtures to transmit electricity. Can be used in both internal and external electrical wiring.
• To transmit communications, cables are used that can conduct current of different frequencies.
• Automation systems use control cables, which are copper conductors located under a protective shield that removes interference and prevents mechanical damage.

Wires

A product formed from several wires or only one is called a wire. In most cases, the winding is plastic, less often wire, but it is also found without insulation at all.

At the moment, greater preference is given to wires whose cores are made of copper or aluminum. Such products are used not only in electrical installation work, but also as windings for electric motors.

They have a low cost, but a huge disadvantage is the impossibility of connecting them with others, for example, copper ones. Copper products can withstand loads well, but in the open air they quickly oxidize and are expensive.

The marking of electrical wires also depends on their purpose. Installation and power are used both indoors and outdoors. Assembly ones, in turn, are used when assembling electrical circuits in switchboards or radio equipment.

Cords

The cord consists of several strands with a small cross-section, which consist of many intertwined wires. Most often, this electrical product is represented by multi-core cords, the winding of which is non-metallic.

The main use of cords is for connecting industrial and household appliances to the network.

Letter marking

Any electrical product must be marked in accordance with GOST standards. The first letter indicates the material from which the core is made. If it is copper, the letter is not assigned, if it is aluminum, then it is marked with the letter “A”.

Explanation and wires The second letter characterizes the type or material of insulation. Depending on the type of wire, it can be written as “P”, “M”, “MG”, “K”, “U”, which corresponds to flat, mounting, mounting with flexible cores, control and installation types of wire. The installation one can also be marked as “P” or “W”.

The next, third letter, means the material of the winding of the product:

• “K” - nylon;
• “C” - fiberglass;
• “BP” or “P” - polyvinyl chloride;
• “F” - metal;
• “E” - shielded;
• “R” - rubber;
• "ME" - enameled;
• “T” - winding with a supporting torso;
• “NR” or “N” - nayrite;
• “L” - varnished;
• “G” - winding with flexible core;
• “O” and “Sh” - polyamide silk as braiding or insulation.

The marking of wires may also have a fourth letter, which characterizes the design features of the electrical product:

• “K” - the wire is armored with round wires;
• “A” - asphalted wire;
• “T” - the product is used for installation in pipes;
• “B” - armored with tapes;
• “O” - the presence of a protective braid;
• “G” - for wire - flexible, and for cable - without protection.

Digital marking

The marking of electrical wires by the first number indicates the number of cores; if it is missing, the conductor has only one core. The second and third digits mean in square millimeters and the rated withstand voltage of the network.

Grounding

For the most part, color coding of wires is intended to facilitate electrical installation work and ensure safety.

According to the ground conductor insulation, it should have a green-yellow color. In some cases, the color may be exclusively green or only yellow.

For grounding, wire color markings are applied either longitudinally or transversely. On electrical circuits, “ground” is usually denoted by the letters “PE”, which is also sometimes called zero protection.

Zero

The zero working contact does not carry a voltage charge, but is only a conductor. The color marking of the wires should be bluish or blue. On an electrical diagram, zero is usually designated as “N”.

Phase

The phase wire is always energized if it is connected to the network. Phase wire color markings can be made in many colors - brown, black, turquoise, purple, gray and others. But most often phase conductors are white or black.

PEN conductor

In any residential building or premises, it is always necessary to ground or ground the electrical wiring. Currently, it is important to carry out a TN-C grounding system, which includes combining the ground and neutral wires. The color marking of wires combined using this system will change from yellow-green to blue.

First, you need to divide the conductor into two buses - PE and N, which are subsequently connected to each other by a jumper in the middle or two at the edges. Then re-ground the PE bus and check the resistance.

How to determine the phase?

Sometimes during electrical repairs or upgrades, it is necessary to determine which wire means what. But it happens that marking wires by color is not an advantage in this, since due to the long service life or in the event of a short circuit this is not possible.

This task can be dealt with using an indicator screwdriver, popularly called a “control”. This method is suitable in the case of a single-phase network, without a ground wire. First you need to turn off the electricity supply, move both conductors apart and turn them on again. After that, bring the indicator screwdriver to one of the wires. If the light on the “control” lights up, then this wire will be a phase, and the remaining wire will be a zero.

If the wiring is three-wire, you can use a multimeter to determine each of the wires. This device has two wires. First you need to set it to a rated voltage of over 220 Volts. After that, fix one of the multimeter wires in contact with the phase, and use the other to determine grounding or neutral. If the second wire detects a grounding conductor, the readings on the device will drop slightly below 220, and if zero, then the voltage will shift within 220 Volts.

The third method of identifying wires can be used if you don’t have a screwdriver or a multimeter at hand. Marking the wires can help with this; in any situation, to isolate the zero, they will be marked in a blue-blue color scheme. The remaining two contacts will be more difficult to determine.

If one of the contacts is colored and the other is white or black, then most likely the colored one will be phase. According to old standards, black and white indicated the grounding conductor.

Also, according to the rules for installing electrical equipment, the ground wire is marked white.

Marking in DC circuit

The marking of wires in a DC network has red insulation color for positive, and black for negative. If the network is three-phase, then each phase will have its own specific color: red, yellow and green. Zero and ground, as usual, will be blue and yellow-green.

If a cable is inserted, the phase wires will have black, white and red insulation, and the color of the neutral and ground will remain unchanged, as is the case with a 220 Volt network.

Independent wire designation

Sometimes, in the absence of a suitable color, you can independently change the color of the same wire used for neutral, phase and ground. In this case, decoding the wire markings will be very useful.

You can make small notes on the wires, which can be very useful later. You can also use colored electrical tape and wrap the wires in accordance with the markings.

Today, cambrics, which are colored plastic tubes that can be heat-shrinkable, are in great demand. If busbars are used, it is also necessary to mark the ends of the conductors.

Anyone may encounter the need to repair electrical wiring or purchase various cable products for a future new home, and the color of wires in electrical installations plays an important role. The reasons for this can be different, but when you start eliminating it, you should count on one encouraging factor: there is color coding of the wires. It’s worth figuring out what it is and why they do it.

Basic definitions

In AC electrical networks up to a thousand volts, the color marking of wires and cables is strictly regulated by state regulations, such as the “Rules for Electrical Installations” (PUE), and this is what the section of the seventh edition in Chapter 1, paragraphs 1.1.29 - 1.1.30 is responsible for. It states that “Identification of wire cores by colors or digital designations” must be used in accordance with GOST P 50462-92 (IEC 446-89). The marking has the following basic designations:

In 3-phase AC distribution boards, the busbars are painted:

• yellow – L1 (phase A);
• green – L2 (B);
• red – L3 (C);
• blue – block of neutral working conductor N;
• alternating longitudinal or transverse stripes of the same width of yellow-green color - PEN grounding bus.

Important! If the electrical panel housing also serves as a grounding contact, then the location where the wires are connected is indicated by a sign (ground) and is colored yellow-green.

The PUE allows you to designate the color of the main wires, phase and zero, not along the entire length of the bus, but only at the points of connection to the contacts; if the bus is invisible, you are allowed not to color it.

Important! When installing electrical equipment located in the same building, it is necessary to use color marking of wires and cables using the same color schemes.

We must not forget that the designation of wires by color should in no case reduce the degree of electrical safety and convenience when repairing or servicing electrical equipment.

electrical safety

Alternating electricity with a voltage of 380V - 220V is a dangerous factor, so if a person touches exposed wires or metal parts of electrical equipment that may be under this voltage without permission, it can result in severe burns or fatal injury! For this purpose, the PUE gives an answer not only to the questions: what color is the grounding wire, or what is PEN, but what is it for.

In order to protect people as much as possible from possible exposure to electric current, electrical safety systems were adopted, characterized by one or more factors, such as:

• grounding;
• protective grounding;
• separation of networks by a transformer.

To ensure safe operation in existing electrical installations up to 1 kV, five grounding systems are used: TN-C, TN-S, TN-C-S, TT, IT with different methods of grounding, grounding and separation of networks. The PUE defines each of the systems as:

1. TN-C, where the working zero N and the grounding PE conductors are combined in one PEN wire. Characterized by: the use of a cable with four cores in a three-phase network and a two-core cable in a single-phase network. This is the oldest device in electrical networks and is still found everywhere for reasons of economy, for example, in street lighting.
2. TN-S, where the working N conductor and the grounding PE are separated from the supply transformer to the end consumer. Such networks are made of five-core cables for a three-phase network and three-core wires for a single-phase network.
3. TN-C-S, where there is one combined PEN conductor of a four-core cable, from the supply transformer to the group panel at the entrance to the building, which is further divided into N and PE, respectively into five and three-wire wiring. This is the most common system for constructing power supply networks for buildings and structures.
4. TT, where there is only one working N conductor, and only the electrical equipment body is grounded. In such a system, four and two-wire wiring are used, respectively. This is how overhead power lines are mainly constructed.
5. IT, where the electrical installation is separated from the power supply network by a transformer and completely isolated from the ground. This is the safest system for humans and is used only for special-purpose consumers.

Thus, the color of the wires phase and zero, L and N in electrics will help to clearly determine the security system used in a given electrical network.

DC electrical networks

Along with alternating current, direct current circuits are used, for example, in on-board networks of cars and electrical household appliances. In such electrical wiring there is no phase wire and neutral wire. The wire color rule in DC electrics is much simpler, since there are only two potentials: positive, denoted in electrical circuits as (+) and negative, signified (-). The colors of such wires are easy to remember: the plus is red, and the minus is black.

Important! For household appliances, these colors are true only for the supply lines; in the further part of the circuit, the positive wire may have a different color.

Practice

Having started directly to electrical installation work or repairs in electrical wiring, you may encounter non-compliance with the color regulations, which are established by regulatory documents. As practice shows, this case is not the rule, but the exception.

Eg:

• you can buy a three-core cable of type BBG 3x1.5, which has cores with white, red and brown colors;
• cable products are often found with white wires with a colored stripe of black, gray or blue along the entire length;
• In the electrical wiring that was done before, in general, you can find a two or three-core white wire.

Here are some practical tips that will come in handy:

1. When making repairs in existing networks, it is necessary to use electrical safety devices, such as a voltage indicator or an indicator screwdriver. With their help you can always determine the color of the phase wire.
2. If the correct color marking of cable products is not available, purchase cambric or insulating tape of the required color. The main thing is to designate the color of the ground wire as yellow-green, the working zero as blue, and for phase L in the electrics you can choose any other color.
3. To install new wiring, use a cable of the same brand so that there is no confusion with the color of the wires in the electrical system.

Color coding abroad

The yellow and green marker of the grounding wire PE and the blue working zero N are designated absolutely identically in all CIS countries, while they are clearly unified with the countries of the European Union. The color designation of the phase wire varies slightly, but this is not of fundamental importance in terms of electrical safety.

In other countries, such as Brazil, the USA, Canada, Australia and New Zealand, the PE ground wire, along with the yellow-green color, can be simply green, and the working zero N is indicated by any of black, white or blue.

In the UK, Australia, New Zealand, Canada and the USA, the PE conductor may not have any insulation at all.

Important! Previously in the USSR, according to the old edition of the PUE, there was color marking that was radically different from today. Thus, the black color indicated the solidly grounded neutral and all grounding conductors, and the white color of the wire corresponded to the working zero.

It is worth remembering that electrical installation work requires an electrician to have knowledge of electrical installations and safety precautions. Once you clearly know the markings, the question of how to choose the right wire color during work will no longer arise, and repairing electrical wiring or installing equipment will become not only safe, but also convenient.

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