Electrical wire colors: typical markings + analysis of nuances

As for DC power networks, they are characterized by the presence of only two buses, minus-negative and plus-positive, which are marked blue and red, respectively. The middle M-wire is usually colored blue or light blue. Neutral and current-carrying wires are fundamentally absent in such electrical networks. If a two-wire network is created from a branch from a 3-wire DC circuit, then its conductors are marked in the same way as the color of the cores of the “mother” network.

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).

Self-labeling

There are times when markings are erased or missing/mixed up. Then, after ringing each conductor, you should independently indicate which core is responsible for what.

If sections of the wire are completely replaced, you can purchase cables of the required color. If it is not possible to purchase a suitable shade, you can make a mark on the ends using colored electrical tape or heat shrink tubing. The rules allow marking the conductor not along its entire length, but only at the points of connection to the busbars.

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

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.

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.

Types of USB connectors - main differences and features

There are three specifications (versions) of this type of connection that are partially compatible with each other:

1. The very first version that has become widespread is v 1. It is an improved modification of the previous version (1.0), which practically did not leave the prototype phase due to serious errors in the data transfer protocol. This specification has the following characteristics:

• Dual-mode data transfer at high and low speed (12.0 and 1.50 Mbps, respectively).
• Possibility of connecting more than a hundred different devices (including hubs).
• The maximum cord length is 3.0 and 5.0 m for high and low transfer speeds, respectively.
• The rated bus voltage is 5.0 V, the permissible load current of the connected equipment is 0.5 A.

Today this standard is practically not used due to its low throughput.

1. The dominant second specification today... This standard is fully compatible with the previous modification. A distinctive feature is the presence of a high-speed data exchange protocol (up to 480.0 Mbit per second).

A clear demonstration of the advantages of USB 2.0 over other interfaces (transfer speed 60 MB per second, which corresponds to 480 Mbit per second)

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.

Classification and pinout

Connectors are usually classified by type, there are only two of them:

• A is a plug connected to the female socket installed on the PC system board or USB hub. Using this type of connection, you can connect a USB flash drive, keyboard, mouse, etc. These connections are fully compatible between the initial version and the second generation. With the latest modification, compatibility is partial, that is, devices and cables from earlier versions can be connected to third-generation sockets, but not vice versa.

  
  Type A connectors

• B – plug for connecting to a socket installed on a peripheral device, for example, a printer. The dimensions of the classic type B do not allow it to be used for connecting small-sized devices (for example, tablets, mobile phones, digital cameras, etc.). To correct the situation, two standard reduced modifications of type B were adopted: mini and micro USB.

Note that such convectors are compatible only between earlier modifications.

Various Type B Connector Models

In addition, there are extension cables for the ports of this interface. At one end there is a type A plug, and at the other there is a socket for it, that is, in fact, a “female” - “male” connection. Such cords can be very useful, for example, to connect a flash drive without crawling under the table to the system unit.

USB Extension Cable

Now let's look at how contacts are wired for each of the types listed above.

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.

Precautionary measures

When charging your smartphone battery, you must follow these rules:

1. Before removing the battery, the gadget is turned off. This will help avoid factory resets and data loss.
2. The above methods cannot be used to charge simple batteries. They differ from batteries in the absence of the “rechargeable” inscription on the case. Failure to follow this recommendation will result in the battery exploding.
3. The battery cannot be recharged. If the charger remains connected to the mains for a long time, the battery capacity will decrease. Harmful to lithium-ion batteries and critical discharge. Charging should begin after the battery power has been reduced to 20%.
4. Once every 2-3 months, battery training is carried out. To do this, the element is completely discharged, after which charging begins.
5. Do not charge the battery in short cycles. This also negatively affects the ability to gain and retain charge.

It is not recommended to use extreme charge recovery methods. They not only damage the battery, but also contribute to injury to the user.

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.

Checking the polarity of the wires

It happens that the wiring has different colors or combinations, or is even completely enclosed in a white shell without any signs. In this case, it is necessary to determine the polarity using tools.

Important! After determining the polarity, it is worth marking the wires so as not to mix them up in the future. The mark can be made with colored tape, permanent marker or heat shrink tubing.

Checking polarity with a multimeter is the easiest way

To help determine the correct polarity:

• Multimeter: This is the simplest option. On the device, you need to set the DC current measurement mode to 20 V, then connect the black probe (minus) to the “COM” socket, the red (plus) probe to the “VΩmA” socket. Then the probes are connected to the wires. If the numbers appear on the screen, it means that the probes are connected correctly - black to minus, red to plus. If a minus sign (“-”) appears in front of the numbers, it means that the probes are connected incorrectly: black to positive, red to negative.

You might be interested in: Features of static electricity

Important! When using a multimeter with an arrow, if connected correctly, the value will be correct; if connected incorrectly, the arrow will deflect in the opposite direction.

An indicator screwdriver is an inexpensive and convenient option

• Indicator screwdriver: when you touch the phase wire, the circuit closes and the control lamp lights up. This is an inexpensive and reliable tool, quite durable and does not require additional resources. The disadvantages include low accuracy and the possibility of false positives.
• Lamp: you need to screw an incandescent lamp into a standard socket, connect the wire to a known zero line and check the others one by one, connecting them. A lit lamp will indicate the presence of a phase.
• Battery: the wires being tested need to be connected at one end to different sides of the battery (to “+” and “-”), and with the other end to touch the speaker terminals for a couple of seconds. If the diffuser moves outward, the wire is connected correctly, if it “retracts” inward, it is incorrect.
• Raw potatoes: cut them in half and stick two wires with their bare ends at a distance of 1-2 cm from each other. The other ends are connected to a DC source, the device is turned on and left for 15-20 minutes. A green spot will form near the positive one, bubbles will appear near the negative one - hydrogen will be released.

Even potatoes can help in determining

• Warm water: one end of the wires is connected to a power source, the other is immersed in warm water. After turning on the device, bubbles will begin to collect near the negative wire.

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".

Mini USB pinout

This connection option is used only in early versions of the interface; in the third generation this type is not used.

Mini USB connector pinout

As you can see, the wiring of the plug and socket is almost identical to the micro USB, respectively, the color scheme of the wires and the contact numbers are also the same. Actually, the differences are only in shape and size.

In this article we have presented only standard types of connections; many manufacturers of digital equipment practice introducing their own standards; there you can find connectors for 7 pin, 8 pin, etc. This introduces certain difficulties, especially when the question arises of finding a charger for a mobile phone. It should also be noted that products are in no hurry to tell how the USB pinout is done in such contactors. But, as a rule, this information is easy to find on thematic forums.

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.

Video

In a charger cable, most often the red wire is positive and the black wire is negative. The white and green wires are used to transmit data.

If the wires do not have color or markings, power is transmitted through the outermost wires on the left and right.

To ensure that the consumer does not get confused which sign (“+” or “-“) and in what place is located on the charger, manufacturers try to mark the wires with different colors.

Basically, “+” corresponds to red, “-“ to black, and less often blue.

On the charger of almost any electrical device, the minus is usually indicated in blue or black, but the plus can be almost any color, but most often it is red and immediately attracts attention.

Yes, it's very simple. All wires on the charger are either positive or negative by color. For example, the red color of the wire always means a plus, and the black and blue wires always mean a minus.

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.

Phase color

When installing electrical wiring, it is the phase conductors that pose a particular danger. If a phase is touched, a person may receive an electric shock, which can be harmful or fatal. Painting in bright colors allows the master to determine that it is a phase conductor in front of him.

Usually the phase is colored red and black, but other colors can also occur (orange, brown, pink, purple, white, turquoise and others).

If the electrician does not know exactly what color the phase is, you can use the method of elimination. The neutral and ground wires have a strictly defined color, and then the remaining core is a phase.

In the diagrams, the phase is designated by the Latin letter L. If there are several of them, a number is added - L1, L2, L3 for three-phase networks of 380 V. The designation A, B and C is also found in electrical networks with three phases.

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).

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.

Features of working with electrical wires of different colors

There are cases when knowledge of phase and zero is not necessary. For example, when connecting a new outlet or replacing an old one. When connecting a plug to it, the polarity is not important and does not affect the performance of the device.

In situations where you need to connect a switch to a chandelier, you need to find out the phase and zero. The phase conductor is connected directly to the switch, and only the neutral conductor is connected to the light bulbs. Otherwise the switch will not work.

The use of conductors of different colors made the work of the craftsmen much easier and sped up the installation process. Also, the color designation made it possible to increase safety when working with live conductors.