How to find out the polarity of wires: determine the colors in electricity, find where the wire is plus and which is minus with a stripe in the wiring it

Determining the polarity of wires is an important skill that is necessary for all advanced equipment users and car enthusiasts. Confusion with minus and plus will, at best, lead to incorrect operation of the device. At worst, it will completely fail or explode due to battery overheating. However, such consequences are easy to prevent, since plus and minus on the wires can be determined in several ways, including without special equipment.

Why do you need vein coloring?

Color coding of the wires allows you to quickly figure out what each wire is responsible for.
Novice craftsmen who are just learning the basics of electrical engineering cannot immediately determine whether the white wire is a plus or a minus. Coloring is important in identifying cores and is called marking. Color marking of conductors is a necessity, allowing the master to quickly figure out what each core is responsible for. With its help you can understand what color the neutral wire is and where the phase is located. It also makes electronic circuits easier to read. It is especially important to observe color markings when connecting to meters, machines, and devices. Without painting, it is difficult to figure out which device may have failed and which circuit it is connected to.

Manufacturers paint cables in certain colors established by the rules of electrical installations PUE. They strictly regulate which markings should be used for a particular core. In addition, it is important to understand that the positive and negative contacts in the DC circuit have their own colors. What color the positive wire is is also determined by the rules.

In the case of an unmarked cable of the same color, a label with information can be placed on the ends of the product (for example, on a heat-shrinkable tube).

Description of poles

In the case of an electric current passing between two points, or poles, one of the poles will have more electrons than the other. The pole with more electrons is said to have a negative charge. The pole with fewer electrons has a positive charge. When two poles are connected by a wire, electrons move from the negative pole to the positive pole. This flow is called electric current.

Polarity can be of different types

For your information! In a DC circuit, one pole is always negative and the other positive with electrons flowing in only one direction. In an alternating current (AC) circuit, the two poles alternate between negative and positive poles with the electrons flowing in the opposite direction.

Features of core colors

To avoid errors, the PUE requirements describe the colors of all main electrical wires. If the commissioning work was carried out by an experienced electrician who follows the rules of the Electrical Installation Code and the relevant GOSTs, during independent repairs you will not need either an indicator screwdriver or other devices that determine the purpose of a particular core.

Color marking in electrical equipment according to GOST

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, the correct connection of the phase conductors will be an important point. 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.

Grounding

The yellow-green wire is grounding. In circuit diagrams, grounding conductors are marked with the letters PE. In some older houses there are PEN wires in which the grounding is combined with the neutral conductor. If the cable was pulled according to the rules, wires with blue insulation were chosen, and only the ends and places of twists were yellow-green (thermal tubes were put on them). The thickness of the “zero” and grounding may be different. Often the thickness of these two conductors is less than the thickness of the phase conductor; this occurs when connecting portable devices.

When it comes to laying electrical wiring in multi-storey buildings and industrial premises, the norms of PUE and GOST 18714-81 come into force, requiring the mandatory installation of protective grounding. Grounding must have minimal resistance to compensate for the consequences of faults on the line and prevent harm to human health. That is, compliance with the standards for color marking of PUE wires is of paramount importance.

Video

Coffee capsules Nescafe Dolce Gusto Cappuccino, 8 servings (16 capsules)

435 ₽ More details

Coffee capsule Nescafe Dolce Gusto Cafe O Le Coffee with milk, 3 packs of 16 capsules each

1305 ₽ More details

Apple iPhone 11 128GB

What GOST and PUE say about color marking

The main document that you should rely on when producing or purchasing cables is GOST 31947-2012. Before its appearance, there was no uniformity and order in the field of color designation of electrical wiring.

Until now, in old houses you can find wires in the same sheath, the color of which cannot determine what is connected - “phase”, “zero” or “ground”.

Now it has become much easier to identify veins. Even without using a tester, you can determine which contact a particular core should be connected to - by the color of the polymer insulation. The above-mentioned GOST document states that the insulation of cable products should differ in color. A certain shade should cover the wire with a continuous layer - from beginning to end. It is impossible for one wire at the beginning of the bay to be blue and the end to be white; Intermittent painting is also prohibited.

The only vein that can have a two-color shell is the “ground”. Officially, it is assigned the green/yellow combination; these two shades cannot be used separately. The regulatory documents also contain recommendations for the use of various circuits for 3-core, 4-core and 5-core cables.

For example, when producing 3-core cables, the following combinations are welcome:

brown – blue – green/yellow;
brown – gray – black.

If the cable consists of 4 cores, then two standard color options are also recommended:

brown – gray – black – green/yellow;
brown – gray – black – blue.

The diagrams for a 5-core wire look like this:

brown – gray – black – green/yellow – blue;
brown – gray – 2 black – blue.

The blue color indicates the “zero” core.

It is not recommended to use only two colors - red and white.

There are special requirements for the distribution of colors of the grounding conductor: on any randomly selected piece of wire 1.5 cm long, one color must cover 30-70% of the insulation, the second color must cover the remaining area. The color must be applied firmly and be clearly visible.

Core marking for electrical installation solutions

It is not for nothing that at the beginning of the article the idea was voiced that the color designation of conductors greatly simplifies the installation process. If you independently do electrical wiring in an apartment or private house, select wires according to the standards, when connecting electrical devices, installing automatic protection, distributing wires in junction boxes, you do not need to double-check where the phase, neutral, and ground are - the color of the insulation will tell you about this.

A few examples of electrical installations where marking is important:

Depending on which electrical installations are connected and where the wires are sent next, the wires are connected in junction boxes
For each core in the socket body there is a special contact. Typically the contacts, screw or clamp, are also marked
The supply conductor is usually connected to the upper, fixed contacts, the ground - to the ground bus
The simplest scheme: the neutral conductor is sent directly to the lamps, and the phase conductor is sent to the switch, from where it is also redirected to the lamps

There are cables with a large number of cores, the painting of which is not practical. An example is SIP, which uses a different method for identifying conductors. One of them is marked with a small groove along its entire length. The relief core usually performs the function of a neutral conductor, the rest play the role of linear ones.

To distinguish the cores, they are marked with tape, heat shrink, and letter designations, which are applied with multi-colored markers. And in the process of electrical installation work, a ringing is required - additional identification.

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.

Checking the correct connection

Unfortunately, not all electricians strictly follow the standards and make mistakes in choosing a conductor when making connections. Therefore, when hanging a chandelier, installing a socket or other electrical installation device, it is better to additionally check whether the insulation of each core corresponds to its purpose.

Mandatory checking of the neutral or phase is dictated by safety standards and the instinct of self-preservation: if you accidentally mix up the contacts during installation, you can get an unpleasant injury - an electrical burn. For identification, installers use two methods: the first is checking with an indicator screwdriver, the second is using a tester or multimeter. The phase is usually determined with a screwdriver, and neutral and zero are determined with measuring instruments.

How to use the indicator?

Even such simple devices as indicator screwdrivers are different. Some of them are equipped with a small button, others are triggered automatically when a metal rod and a current-carrying conductor or contact are connected.

But all models without exception have a built-in LED that lights up under voltage.

The indicator screwdriver is preferred by amateurs who do not have special qualifications. Professional electricians value accuracy, so they always have a tester with them. A screwdriver is a convenient tool for identifying the phase conductor. To find out whether the wire is working, use the metal blade of a screwdriver to gently touch the exposed wire.

If the LED lights up, the wire is energized. The absence of a signal indicates that it is ground or zero.

When using the indicator, you must adhere to the safety rules. Even if the screwdriver handle is insulated, it is recommended to wear protective gloves (with a rubberized inner layer), as when working with electricians in general. The verification procedure is performed with one hand, therefore, the other is free. It is better to also use it - for example, to fix wires. But it is strictly forbidden to touch the exposed parts of conductors or metal objects located nearby (pipes, fittings) with your second hand.

Rules for using the tester

An electrician's kit always includes a tester or multimeter. He has to work with the connection of conductors in electrical installations indoors and when assembling an electrical panel. If the wiring was installed a long time ago, marking the wires by color can be neglected.

Even if the insulation colors seem to be consistent, it is not a fact that they are connected according to all the rules.

Using the tester, you can find out not only the likelihood of connecting conductors to the electrical network, but also some parameters: current, resistance, voltage. With a multimeter you can test diodes, check transistors, and determine inductance. Before taking measurements, you should study the instructions that accompany all measuring instruments.

The procedure is approximately as follows:

we set a value that is obviously higher than the expected voltage, for example, 260 V;
connect the probes to the required sockets;
we touch two conductors with probes - presumably phase and neutral;
repeat the procedure with another pair of conductors.

The combination of phase-zero cores should produce a result close to 220 V. It will always be higher than the phase-ground pair. There are both digital, modern instruments on sale, as well as outdated ones, with arrows and value scales. It is more convenient to use digital ones. Before installing electrical devices yourself, we recommend learning how to use either an indicator screwdriver or a multimeter - you should not rely only on the color of the wires.

Determining polarity with a multimeter

Sometimes it happens that a new electrical device that needs to be connected does not have polarity markings or it is necessary to re-solder the wiring of a damaged device, and all the wires are the same color

In such a situation, it is important to correctly identify the poles of the wires or contacts. But if you have the necessary instruments, a logical question arises: how to determine the plus and minus of an electrical appliance with a multimeter?

To determine the polarity, the multimeter must be turned on in the mode for measuring direct voltage up to 20 V. The wire of the black probe is connected to the socket marked COM (it corresponds to the negative pole), and the red one is connected to the socket with the VΩmA marker (it is, accordingly, a plus).

After this, the probes are connected to the wires or contacts and the device, the polarity of which needs to be determined, turns on. If the multimeter display shows a value without additional signs, then the poles are determined correctly, the contact to which the red probe is connected is positive, and the contact to which the black probe is connected will correspond to the minus. If the multimeter shows a voltage value with a minus sign, this will mean that the probes are connected to the device incorrectly and the red probe will be a minus, and the black probe will be a plus.

If the multimeter used to measure is analog (with an arrow and a display with gradations of values), if the poles are connected correctly, the arrow will show the actual voltage value, but if the poles are reversed, then the arrow will deviate in the opposite direction relative to zero, that is, it shows a negative current value.

How to determine ground, zero and phase on wires if there are no markings

It is more difficult to determine in practice than in theory. Not all manufacturers comply with the standards. Therefore, when laying a two-phase 220 V network with grounding, you have to use a VVG cable with blue, brown and red colors. Combinations may be different, but without complying with regulatory requirements.

For your information. In old wiring from “Soviet times” there is no color marking. Identical white (gray) shells do not allow the purpose and correspondence of the lines to be known by simple visual inspection.

To avoid problems, it is recommended to carry out installation work using the same type of cable products. When color coding is not available, it should be created at the joints using insulating tape or heat shrink tubing. The latter option is preferable, as it is designed to maintain integrity for a long time.

Below are methods for determining phase and neutral wires with the advantages and disadvantages of each option. In any case, first clarify the network parameters. In old houses, for example, a two-wire connection scheme with a single working and grounding conductor is often used.

TN-S grounding diagram. The figure shows a modern network with separate grounding and working zero connections. It is possible to connect three- and single-phase loads.

Determining the phase using an indicator screwdriver

Touching the tip of such a device to the phase wire closes the current circuit. This is accompanied by the warning lamp or LED lighting up. A built-in resistor limits the current to a safe level.

Design of an indicator screwdriver.

Advantages of the indicator:

minimum cost;
compactness;
reliability;
durability;
autonomy;
good protection from adverse external influences.

The disadvantage is the limited measurement accuracy. Under certain conditions, false positives cannot be ruled out.

Determination of ground, zero and phase using a test lamp

To reproduce this technology, you need to prepare a simple design. An incandescent lamp designed for the appropriate mains voltage is screwed into a standard socket. Connect wires of sufficient length to perform work operations in a specific location. Next, connect one of the wires to the known zero line. Others sequentially check other cable cores. Lighting of the lamp indicates the presence of a phase.

Using a measuring device

When checking a 220 V household network, you do not need to know how to determine the polarity. The power supply is organized using alternating current, so set the multimeter switch to the appropriate position. Touching the phase-zero (phase-ground) wires with the probes is accompanied by an indication of the corresponding voltage (≈220 V). The potential difference between the neutral conductor and ground is minimal.

When checking an old two-wire circuit, one of the probes touches the reinforcement in a concrete slab, a radiator of a heating system, or another grounded element of a building structure. When switching to constant voltage, the multimeter will show where the plus and minus are. In the absence of reliable information about the electrical parameters in the circuit, they begin with the maximum measurement range with a sequential transition to smaller values with insufficient accuracy.

Such a “device” is useful for testing DC circuits in the absence of specialized measuring instruments. Bubbles near the negative wire are the release of hydrogen during the electrolysis reaction. The area near the plus will take on a greenish tint after a few minutes.

Using LED

You can create a control device with your own hands by analogy with an indicator screwdriver. Instead of a light bulb, install AL 307 or another LED with similar characteristics. A 100-120 kOhm resistor with a power of 1-2 W is added in series to the circuit.

Wire Classification Options

The typical cable name contains letters and numbers. By decoding these symbols you can find out the main characteristics of products in this category:

conductor (shell) materials;
number of cores;
cross-sectional area;
Extra options.

Example of decoding (AVBbv-ng):

A – the core is made of aluminum (copper is not marked);
B – insulating shells are made of PVC;
BB – protection against mechanical damage, made of steel tape without a damping gasket;
ng – components that prevent combustion have been added to the polymer shell.

Ground wire color

By modern standards, the ground conductor is yellow-green. It usually looks like yellow insulation with one or two longitudinal bright green stripes. But there are also transverse yellow-green stripes in color. This color can be grounding.

In some cases, the cable may only have yellow or bright green conductors. In this case, the “earth” has exactly this color. It is displayed in the same colors on diagrams - most often bright green, but it can also be yellow. Signed on circuit diagrams or on ground equipment in Latin (English) letters PE. The contacts to which the “ground” wire must be connected are also marked.

Sometimes professionals call the grounding wire “neutral protective”, but do not be confused. This is an earthen one, and it is protective because it reduces the risk of electric shock.

What color is the neutral wire?

Zero or neutral is blue or light blue, sometimes blue with a white stripe. Other colors are not used in electrical engineering to indicate zero. It will be like this in any cable: three-core, five-core or with a large number of conductors.

What color is the neutral wire? Blue or light blue. “Zero” is usually drawn in blue on diagrams and signed with the Latin letter N. Experts call it a working zero, since, unlike grounding, it participates in the formation of the power supply circuit. When reading a diagram, it is often defined as "minus", while the phase is considered "plus".

Determine visually

The first way is visual. Let's say you need to determine the polarity of a brand new LED with two leads. Look at its legs, that is, its conclusions. One of them will be shorter than the other. This is the cathode.

You can remember that this is a cathode by the word “short”, since both words begin with the letters “k”. The plus will correspond to the pin that is longer. Sometimes, however, it is difficult to determine the polarity by eye, especially when the legs are bent or have changed their sizes as a result of the previous installation.

Looking into the transparent case, you can see the crystal itself. It is located as if in a small cup on a stand. The output of this stand will be the cathode. On the cathode side you can also see a small notch, like a cut.

But these features are not always noticeable in LEDs, since some manufacturers deviate from the standards. In addition, there are many models made according to a different principle. Today, on complex structures, the manufacturer puts “+” and “−” signs, marking the cathode with a dot or a green line, so that everything is extremely clear. But if there are no such marks for some reason, then electrical testing comes to the rescue.

Color of wires plus (+) and minus (-) in DC networks

Is the red wire positive or negative? Such questions arise when working with DC electrical circuits.

Red

To remember which plus is red or black, they use the name of a well-known international organization - the Red Cross. This phrase suggests that red means plus.

Black

Black color indicates the negative conductor. These markings can be seen on typical household equipment:

power supplies;
audio, video equipment;
other devices with electronic software control units.

Plus

The polarity of conductors must be observed when repairing standard electrical equipment of cars. In some situations, confusion with plus and minus is accompanied by a violation of the functional state.

Minus

The high power of connected consumers increases the responsibility for performing repair and adjustment work. In such situations, it is necessary to eliminate errors in determining polarity. Strong direct current is used to supply electricity:

warehouse and municipal transport;
lifting mechanisms;
sensors and automation.

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 is the 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.

Capacitor Characteristics

The main characteristic of any capacitor is its capacity, which determines the amount of accumulated charge. The capacitance depends on the area of the plates and the thickness of the dielectric layer.

Attention! The area of the plates cannot be increased indefinitely, as this leads to an increase in the dimensions and weight of the device. The thickness of the dielectric layer can also be reduced only to a certain value, since any insulator has its own electrical strength limit

In this regard, the second main characteristic is the operating voltage at which the capacitor retains its properties throughout its entire service life

The thickness of the dielectric layer can also be reduced only to a certain value, since any insulator has its own electrical strength limit. In this regard, the second main characteristic is the operating voltage at which the capacitor retains its properties throughout its entire service life.

Exceeding the operating voltage leads to electrical breakdown and malfunction of the device, in particular, in some applications it is necessary to take into account additional parameters, namely:

Temperature coefficient, which takes into account the effect of heating on the capacity of the radio element;
Dielectric loss tangent, characterizing the properties of a radio element when operating at high frequencies;
Switching polarity, which arises due to the design features of certain types of devices.

To increase the capacity while maintaining acceptable dimensions, it is necessary to apply various technical subtleties. For example, in electrolytic capacitors, a narrow and long strip of aluminum foil is used as one of the plates. A thin layer of oxide on the surface of the foil acts as an insulator, and a liquid electrolyte is used instead of a second plate. To make such a capacitor, a sheet of foil is rolled into a thin cylinder, which is then placed in the housing.

Electrolytic capacitor

This design combines a large plate area and a small dielectric thickness, which makes it possible to obtain very large capacitance values with small dimensions.

The main disadvantage of such capacitors is the need to strictly observe the polarity of the connection. Failure to comply with this requirement leads to high currents, leaks and structural failure. Electrolytic capacitors must have polarity markings for proper connection.

Additional marking of wires

If the purchased cable has conductors of a color that does not comply with the standards, or the wiring has already been laid and is incorrectly marked, additional identification must be carried out.

Additional marking of wires.

During the electrical installation process, the ends of the wires are marked using heat-shrinkable tubing or colored insulating tape. Additionally, the letter designation of the cores can be applied to the wire or a tag attached to the wire:

L – phase.
N – neutral (working zero).
PE – ground (protective grounding).

Neutral color

What color the neutral wire is is specified by GOST , so when looking at the installation of a power plant, the question should not arise whether the blue wire is a phase or a 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 use of blue and cyan insulation is to indicate the negative pole or midpoint in DC circuits. This color cannot be used anywhere else.

Security measures

When working with electric current, the following precautions must be taken:

Use devices only for their intended purpose;
Do not turn on equipment with damaged wires and plugs, do not use faulty sockets;
Do not touch wires or outlets with wet hands or while standing on a wet floor. When working in a room with high humidity, you need to use rubber gloves and a mat;

Do not bend wires and cables;
Before starting work, it is worth disconnecting the entire network;
If the equipment sparks or starts to catch fire when turned on, do not touch it. It is necessary to turn off the power through the panel;
If you have any doubts or fears, it is better to contact a specialist or choose a safer option, for example, determining the polarity using a potato rather than connecting to a device.

Most often in batteries, the red wire indicates positive, the black wire indicates negative, and there are no problems when working with electricity. However, today many countries use their own color designations or abandon them altogether, leaving the wires uniformly white. In order not to create emergency situations, it is worth checking the polarity first.

Determining polarity with a multimeter

In such a situation, it is important to correctly determine the poles of the wires or contacts

But if you have the necessary instruments, a logical question arises: how to determine the plus and minus of an electrical appliance with a multimeter?

After this, the probes are connected to the wires or contacts and the device, the polarity of which needs to be determined, turns on.

If the multimeter display shows a value without additional signs, then the poles are determined correctly, the contact to which the red probe is connected is positive, and the contact to which the black probe is connected will correspond to the minus.

If the multimeter shows a voltage value with a minus sign, this will mean that the probes are connected to the device incorrectly and the red probe will be a minus, and the black probe will be a plus.