Power cable cores: types, features, application

For a person who is not an electrician, there is no difference between a cable, a wire and a cord. In fact, in our country alone, according to various GOSTs, more than 20 thousand different cables and wires are produced, and in addition to domestic products, there are also foreign ones, so the range of cable products is very extensive. Fortunately, you don’t need to understand all the different types of cables and wires—it’s enough to understand the general principles of their purpose and be able to read the markings. In the article we get acquainted with the main types of wires, talk about cores and insulating materials, and also find out the general principles of marking cable products.

Origin of the term

The word "cable" is of German origin. Cabel is always something extended; this root is often found in marine terminology.

• Kabeltov is a maritime unit of length, 1/10 of a mile, equal to 185 meters.
• A cable cable is a structure whose strands are woven fourfold.

Therefore, it is academically correct to use it in relation to conductive parts that have an infinitesimal thickness compared to their length and consist of three or more metal conductors isolated from each other.

What is the difference between cable and wire

In order to understand the difference between a cable and a wire, you need to consider them in detail. We already know what a cable is. For a more detailed study, it’s time to get acquainted with its classification and varieties. First of all, they are divided into application groups:

• power;
• installation;
• communications;
• management;
• radio frequency;
• optical.

Power ones are designed to transmit electricity. They are laid permanently and used when connecting mobile electrical consumers.

The required elements included in the cable are:

1. conductor;
2. its isolation;
3. shell.

Made from copper and aluminum. Supply voltage – up to 750 kV. They have a long service life (30 years). The best insulation is made from cross-linked polyethylene.

Mounting plates are used for inter-device installation of electrical devices. Supply voltage – up to 500 V. The main material of the current-carrying conductors is copper. They have stable performance at elevated temperatures.

Communication cables are used in signaling and wire communications. For example, a corrugated cocoon-shaped waveguide is used in radio engineering and radar systems. Widely used for intercity, interregional and city communications.

Control cables are used for control and lighting circuits in machine tools and other mechanisms with voltages up to 600 V. Radio frequency and optical media transmit energy and signals at certain radio frequencies or in the optical range.

In addition to groups, these electrical conductors have a number of characteristics by which they are classified. This includes parameters such as insulation, shielding, the number of current-carrying cores and their material from which they are made. There are a number of other signs of cable division. The classification of electrical products is described in detail in the ISO 11801 2002 standard.

Power cable marking system.

The letters and numbers indicated on the product will help you quickly understand what type of product is in front of you. To decipher, it is necessary to take into account not only the symbolic designations of certain characteristics, but also their position. According to accepted standards, power cable marking is based on the principle indicated in the table below.

In order to quickly find the right brand when viewing a cable catalog, it is important to remember not only the decoding of the alphanumeric designations, but also the type of characteristics reflected on each individual position.

Types of electrical cables

The modern industry producing electrical products is ready to offer consumers a huge assortment of cable products. Each type of electrical cable or type of wire is used to solve a specific professional task of electrifying a facility. Any person who decides to install electrical wiring on a personal summer cottage, in his own city apartment or private house will soon understand that copper conductors are most often used for such work and aluminum conductors are much less often used. There are simply no other options, although there are quite a lot of metals with low current resistance.

Why copper and aluminum? Yes, everything is very simple! These are the cheapest non-ferrous metals, optimally suited for the production of wires due to their technical and design characteristics. Of course, it is quite possible to make a cable from gold, but the price of this product will be prohibitive!

Cable products and wires for installation of electrical wiring in residential and other facilities are divided into several types and types: powerful power cables, special self-supporting cables, electrical wires for hidden and open wiring, installation conductors, and so on.

The range of basic characteristics of such electrical products is varied. All cable electrical products are divided into categories not only according to their purpose, but also according to the type of insulating layer, the structure of current-carrying conductors and the metal from which they are made, design features and other parameters.

Choosing the right electrical cable or wire is a very responsible matter, on which the safety of your property and your own health depends. Therefore, for those who do not want to face such catastrophic events as a short circuit, fire or electric shock, we recommend that you carefully select electrical products that meet the requirements of the Electrical Installation Code (PEU).

Table for decoding letter markings of power cables.

In some cases, marking power cables (deciphering which for an untrained person seems like a real nightmare) can become a significant difficulty in tasks related to cable and wire products. In fact, deciphering the cable markings is not that difficult. The detailed meaning of each letter symbol of the cable brands is given in the cable catalog tab and the table below:

Conditions of use

Cable, unlike wire, has found wider application in special conditions. Having increased protection against mechanical and aggressive damage, it is laid under water. All underground communications are carried out only by him. In addition, they are used in mines, fire hazardous areas, areas with increased corrosive activity and other places.

Wires are used only inside electrical distribution devices. Outside these limits, it is recommended to use cables or conductive bars. As an example, consider the PV-3 wire. This is an installation copper wire with a stranded core. Suitable for use in baths and bathrooms. Does not burn. It has found wide application in the installation of apartment electrical wiring. It has increased flexibility, which makes it different from other wires.

Types of wires

You should choose a suitable wire based on the power of the equipment that will be powered through it. Let's understand what types of wires exist and how they are used in everyday life.

Flat

Flat wires have a rectangular cross-section. Such wires contain one or more cores arranged in one or several layers. Flat wires are divided into several types:

• PBPP (PUNP)
  . Single-wire wires that are used to connect sockets or lighting fixtures. The cross-sectional sizes of cores in PUNP wires vary from 1.5 to 6 mm². Flat protected wires PBPP (PUNP) have both external and internal PVC insulation, which allows them to be used at temperatures from −15 to +50 degrees. Such wires bend easily and transmit voltage up to 250 W.
• PBPPg (PUGNP)
  . According to the main characteristics, PBPPg are no different from PBPP, except for increased flexibility. The letter “g” in the abbreviation indicates precisely the flexibility that is achieved by the presence of stranded conductors. The bending radius is 6 diameters, while in PUNP wires it is 10 diameters.
• APUNP
  . The wire contains a single-wire aluminum core with a cross-section of 2.5 to 6 mm². All other parameters coincide with PBPP and PBPPg.

Please note that the provisions of the PUE prohibit the use of APUNP wires; their production continues only because of the low price and, as a consequence, high demand. Flat wires should only be used to connect lighting fixtures.

With jumpers

There are two types of jumper wires:

• PPV
  . Such wires have 2-3 single-wire cores, and the wire itself is insulated with PVC. Excellent transmission of current with a frequency of up to 400 Hz and voltage of up to 450 W. PVC insulation is resistant to alkalis, acids, low and high temperatures from −50 to +70 ° C, and also withstands 100% humidity conditions. The permissible bending radius is 10 diameters. A distinctive feature of the PPV wire is the characteristic PVC jumper. Core cross-section is 0.75–6 mm².
• APPV
  . It has the same parameters as PPV, it differs only in the cross-sectional size of the cores - in APPV it is from 2.5 mm². Suitable for lighting and power open wiring.

Single-core

Single-core wires are distinguished by multi-color insulation - with the help of bright colors it is more convenient for electricians to install distribution boards without the use of additional markings. Wires with one core are divided into three types:

• APV
  . Aluminum wire with one core (single-wire - 2.5–16 mm²; multi-wire - 25–95 mm²). Thanks to PVC insulation, it can be used in conditions of 100% humidity and can withstand both extremely low and high temperatures (up to +70 °C). Resistant to chemicals.
• PV1
  . The number in the abbreviation indicates the flexibility class. The wire consists of a single-wire copper core (cross-section 0.75–16 mm²) and multi-wire (cross-section 16–95 mm²).
• PV3
  . The stranded flexible core as part of the PV3 wire is used when installing lines with multiple bends and transitions.

Classification

To prevent confusion, cable types are identified by their functional purpose.

Power cables

They are usually called those that carry three-phase current. They are laid between distribution boards and are also used to connect electrical machines - generators or asynchronous motors. For household electrical networks, the phase-to-phase voltage in them is 380 volts.

If it is impossible to lay overhead electrical lines, cables with voltages from 1 to 35 kV are used. In exceptional cases, a main electric current of up to 220 kV is carried through the power cable - this is used, for example, to supply electricity to Crimea along the bottom of the Kerch Strait.

Power cable - marking features

The properties and design features of power cables, as well as the scope of application, are determined by the marking of cable products. Today, there are two types of marking of such products: color or letters. In the Russian Federation, the alphabetic one is used, where each character and its location has a specific meaning. The first character indicates the material of the core and if it is “A”, then it is made of aluminum, and if there is no letter, then it is made of copper. The table below shows the order of marking signs, their letter designation and interpretation.

Basic cable types

Table 3.23

How does an electrical cable work?

The cable design consists of two elements:

1. Current-carrying conductors - copper or aluminum, single or consisting of several conductors, coated with a dielectric material. Conducting conductors can be collected in packages, which, in turn, have a sheath made of dielectric, lead or aluminum.
2. External dielectric shell.

Single conductors are used in cables whose current strength does not exceed 25 amperes. Stranded wires have greater electrical strength with a smaller cross-sectional area due to mutual compensation of surface currents, which lead to heating, melting and subsequent physical breakage. In addition, a package of multiple conductors is more flexible and easier to lay, since the permissible bending radius of the cable (without leading to destruction of the internal insulation layer) is smaller.

Aluminum has a higher resistivity than copper (0.028 versus 0.017 Ohm/mm2) and a lower melting point (660 and 1085 0C, respectively). Therefore, to obtain the same electrical strength, aluminum conductors must be twice as thick, which is not particularly significant for currents up to 16 A and is a decisive fact in favor of choosing copper conductors for heavy loads in the network.

In addition, practical experience in installing electrical wiring shows that wires made of this material tend to break when repeatedly twisted or subject to significant vibration loads. However, cables with aluminum conductors are cheaper and weigh less, so they were widely used during Soviet times.

The cable screen - the outer sheath - plays the role of not only dielectric, but also physical protection. Therefore, those that are used in unfavorable conditions, for example, are laid in the ground or where they can be damaged by mechanisms or tools, are wrapped with metal tape on the outside and are called armored. Their screen consists of three layers:

1. Cushion – fibrous materials impregnated with bitumen. Serves to protect against damage to the insulation of current-carrying conductors by the edges of the armor tape.
2. Metal (steel or copper) tape - armor protection.
3. Cover - bitumen compounds or polyethylene protective hose.

Alphanumeric marking of power cables.

Having figured out the sequence in which cable characteristics are marked, you can begin to directly decipher them. Currently, there are more than 300 product brands that have their own coded designation. The table below will help you understand the most common lettering instructions that are used to describe product properties.

The first number after the letters indicates the number of conductive wires. After the “X” sign, their cross-sectional area is indicated. If neutral conductors are provided in the cable design, then after the number and cross-section of the main conductors a “+” sign is placed with a further indication of the number of conductors of smaller cross-section and their exact area.

Copper or aluminum?

Again, this question is often asked by people who have nothing to do with electrical installation and do not know the PUE (electrical installation rules). If you don’t go into details, the answer will be unique and obvious: copper. However, wires with aluminum cores are still used. The main reason is their low cost. But whether you need to save on this is a more interesting question.

Let's look at the main disadvantages of aluminum:

• Lower conductivity (therefore, with similar current conductivity indicators, the cross-section of aluminum wires and cables will be larger);
• Low strength, cannot be bent repeatedly;
• Susceptibility to rapid oxidation, resulting in a short service life.

And let us remind you that the only advantage is the low price. But in the end, if we talk about savings, it is far from a fact that aluminum wires will be cheaper, since copper wires have a longer service life. And if we talk about the long term, then copper turns out to be more profitable. In any case, it is more reliable, so you should only choose copper wires.

It is also important to remember that it is not only the selection of the correct wire and cable that matters, but also its high-quality installation. This is a question not only of service life, but also of safety. If electrical wiring is done correctly and in compliance with all standards, it can last for decades. Therefore, if you have no experience at all, then you can choose and buy wires yourself, but it is better to entrust their installation to professionals. This is the case when saving is not worth it.

Cable catalog.

Depending on the design features of the conductive product, its symbol may not contain all parameters. So for an aluminum electrical cable, the marking begins with the letter A. If it is not in the first position, this means that this is a product with conductive copper cores. The following letters indicate what the insulation is made of. This term refers to the protective covering of conductors, which is necessary to prevent them from shorting with each other. The insulation material is designated by the abbreviations V, P, Pv, Ps, R, NR, F, C, K, KG. The following letters will tell you the type of inner containment used. It is laid on insulated cores and provides higher cable resistance to water, mechanical damage, and extreme temperatures. The internal protective shell is designated by the letters A, C, P, Pu, B or P, but is not present in all products. Therefore, if there is a blank in the 3rd position, this means that this structural element is not included in the product. An equally optional element is armor, the type of which is indicated on the 4th position of the marking with the abbreviations BS, BbG, Bb, Bl, Bn, K, D, P. The armor is made of steel tapes or wire braiding and is needed to increase the mechanical strength of those wires and cables that bear increased load. Most often, protection is provided by a simple outer shell. It is made of dielectrics: fluoroplastic, polyethylene, PVC or rubber. The specific material is indicated by the letters V, Shv, Shp, Shps, N on the 5th position of the power cable marking. The letters O, E, G may also appear here, which indicate the design features of the product.

If we consider the digital markings that occupy the 6th and 7th positions, then they are always present. In some cases, numbers may be included to indicate the level of permissible operating voltage. If this is not the case, it means that the cable is designed for a 220 V network. Climatic zones of operation may not be indicated (they are used only on special-purpose products) and the number of GOSTs and TUs used.

Types of insulating materials

The type of dielectric used directly depends on the network voltage.

Polymers – polyethylene and polyvinyl chloride (PVC). Cheap, light, flexible. They allow diffuse penetration of water vapor, therefore they are not used for insulating current-carrying cable cores operating in conditions of constant humidity. Polyethylene is flame retardant, but PVC is not. Dielectric properties are maintained up to a network voltage of 5 kV.

Technical rubber is a material that is absolutely impermeable to moisture. Dielectric properties are maintained up to a voltage of 10 kV. Resistant to all types of mechanical loads, does not propagate combustion. However, it begins to collapse at a core temperature of more than 70 0C. It is also prone to aging, as a result of which it crystallizes and becomes brittle. It is accelerated by ultraviolet radiation and ozone.

Marking of cable lines.

Wires and cables laid in boxes and on trays must be marked at the beginning and end of the trays and boxes, as well as at the points where they are connected to electrical equipment, and the cables, in addition, also at route turns and branches. Each cable line must be marked and have its own number or name. Labels must be installed on exposed cables and cable joints. Tags must be secured to the cables with nylon thread or galvanized steel wire with a diameter of 1 - 2 mm, or plastic tape with a button. The place where the tag is attached to the cable with wire and the wire itself in damp rooms, outside buildings and in the ground must be covered with bitumen to protect it from moisture. On hidden cables in trenches, tags are installed at the end points and at each coupling. Tags should be used: in dry rooms - made of plastic, steel or aluminum; in damp rooms, outside buildings and in the ground - made of plastic. Designations on tags for underground cables and cables laid in rooms with a chemically active environment should be made by stamping, punching or burning. For cables laid in other conditions, markings may be applied with indelible paint. On cables laid in cable structures, tags must be installed at least every 50 - 70 m, as well as in places where the direction of the route changes, on both sides of passages through interfloor ceilings, walls and partitions, in places where cables enter (exit) into trenches and cable structures. On hidden cables in pipes or blocks, tags should be installed at the end points at the end couplings, in the wells and chambers of the block sewer system, as well as at each connecting coupling.

Cable markings

The cable model index includes letters and numbers containing information about the type of core material and insulation, and the diameter of the conductors. Let's consider a specific example: ANRBG - 3x16+1x10.

1. The first letter - A - means that the current-carrying conductors are made of aluminum. When using copper, the letter is skipped.
2. The second letter – N – type of insulation. In this case - non-flammable rubber. Options: P – polyethylene, B – polyvinyl chloride, P – regular rubber. If paper is used, the sign is skipped.
3. The third letter - P - rubber insulation of the shell. Options: A – aluminum, C – lead.
4. Quarter letter - B - type of armor coating. Options: B – steel strip, P – flat wire.
5. The fifth letter is the type of armor cover. Options: G - without it (bare), Shp - polyethylene hose, if the letter is missing, then bitumen or cable yarn is used.

The first set of numbers: three current-carrying conductors with a cross-section of 16 mm² each. The second set of numbers: one grounding wire and its cross-section.

Now you have an idea of ​​what a cable is and how complex its design can be. Please don't think of it as a type of clothesline.

Shorted or broken conductors in a cable or wire

To determine whether there is a short circuit between the wires in the cable or to verify the integrity of the wire, you need to take a tester, multimeter or indicator screwdriver. It is necessary to “ring” the cable wires so that they do not ring each other, for example, the blue wire at one end and the white wire at the other. But at the same time, same-color (of the same name) conductors from different ends of the conductor must be called.

But the case of broken or shorted wires is a case of defects, and now let’s move on to issues that relate to the manufacturer’s desire to save more and reduce the cost of the cable as much as possible, and, as a result, make it cheaper.