Any industrial products, including cable and wire products for power engineering, are usually classified and described strictly according to certain criteria, which are called technical characteristics. They allow you to optimally choose a specific model from a wide variety of available products, ensure its long and trouble-free operation.
During installation and operation, the cables are exposed to mechanical and thermal loads acting in different directions. To protect themselves from their destructive effects, protection is created-the outer shell or additional armor of various designs.
Protective shells are created in hermetic design. They additionally prevent the destructive effect of groundwater, acids and alkalis contained in the soil, where cables are most often placed.
Infringement of tightness of a cover of a cable leads to formation in it of a moisture which reduces resistance of a dielectric layer and can become the reason of breakdown of isolation.
An important characteristic of the insulation and protective coating of the cable is its property to withstand fire. Under normal operating conditions, the dielectric layer is only exposed to the operating temperature created by the load. It is not critical for its application.
However, in emergencies, some materials, such as paper and oil, are susceptible to ignition and themselves are then sources of fire spread.
Others may simply not support combustion, but melt, break down from the effects of high temperatures. Cables with such insulation are called "not supporting combustion" and in the labeling are denoted by "ng" indices.
They are divided into two groups that do not support the combustion process when:
1. Single strip:
2. group placement.
The selection of cable products for industrial purposes is carried out by engineers of design organizations. We will consider how to independently carry out this question for domestic purposes.
How to choose a cable and wire for home wiring
Just note that the old rules that allow the use of aluminum and its alloys for wires and cables of residential buildings, no longer apply. The reason for this is low mechanical stresses and a tendency to break when deformed and bent.
For this reason, old aluminum wires, mounted in the Soviet era, are gradually improving their resources. In modern electrical wiring, only copper is allowed to be laid.
To permanently not engage in complex electrical engineering calculations of the cores of wires with permissible temperature heating from the running loads, the following table is created.
Area ratio copper wires On permissible load currents and consumer power for household wiring.
The range of cable products is very extensive. For household purposes are popular:
wire brands: PUNGP, PVS; PV;
cables brands: NYM; VVGng; VVGngls.
Electrical wiring should be safe, reliable and economical in the sense that it is necessary to buy wires that are optimally suited to your needs, and not just by the principle - the more expensive, the better.
Before you begin to install electrical wiring in a house or apartment you need to decide how much and what cable you need.
1. on the installation diagram in the project documentation;
2. Measuring directly the surface on which the electrical networks will be laid.
Regardless of the measurement method, add 10 centimeters to each connection of the wire for installation and connection in a box, switch, outlet and so on.
Marking of electrical wires and cables
The cable mark is an alphabetic designation characterizing the material of the conductors, insulation, degree of flexibility and the construction of the containment. Usually 4 symbols are used, sometimes there are more letters, but this is done for marking special wires and electric cables.
The following designations are used in the marking of domestic wires:
first letter indicates the material of the conductor (for example, A is aluminum), the absence of a letter in the wire mark means that the wire is made of copper, for example, BBG-copper conductor, ABBG-aluminum;
third letter insulation material, B or BP - polyvinyl chloride, D - double winding, K - kapron, P - polyethylene, P - rubber, PR or H - non-flammable rubber, C - glass fiber, Ш - polyamide silk, E - shielded;
fourth letter indicates the features of the cable design, for example, B - armored with bands, D - flexible, T - for laying in pipes, K - armored with round wire, O - in braid.
In the notation electrical wires there are lowercase letters, they are put at the end, for example, VVGng - incombustible VVG, VVGz - filled VVG.
After the letters are written numbers, the first of which indicates the number of conductors, and the second section of each of them, for example, 3 × 6 PVA means that the wire has 3 cores of 6 mm 2.
When carrying out electric wiring in apartments and houses, usually use such basic types of cables.
In the image: wire ПБПП.
BSPP (PPPP) - is an installation or mounting electric flat wire, with copper single-wire veins, covered with PVC insulation. Number of cores 2 or 3, section from 1.5 to 6 mm 2. It is used for laying lighting systems and installing sockets. Rated voltage up to 250 V, frequency 50 Hz, operating temperature range from -15 to +50.
PPBS (PUGNP) differs from the previous wire in that the strands are multiwire, so the name contains the letter "g". The technical characteristics are the same as for the previous wire, but it is better bending, so it is more convenient for wiring with a lot of bends.
APUNP - has 2 - 3 aluminum single-wire cores, has the same characteristics as the previous wires, but it can not be multiwire, so it is less flexible.
In most cases, these 3 types of wires are enough to perform any domestic internal networks.
In the image: flat ribbon wire PPV
PPV - Copper flat wire with PVC insulation and dividing bridges. A single-wire vein, 0.75 - 6 mm 2, number of cores 2 - 3. Used for installation of lighting systems and laying of power lines. Rated voltage up to 450 V, frequency up to 400 Hz.
Wire well tolerates mechanical damage, vibration and aggressive environment, does not burn, can be operated from -50 to +70 ° C. Moisture resistance 100% at a temperature of 35 ° C.
In the image: aluminum wire APPV, it is two- and three-core.
APAP - flat two- and three-core aluminum wire, has the same characteristics as PPV.
APO aluminum solid conductor with insulation from PVC, cross-section of single-wire veins from 2.5 to 16 mm 2, stranded from 25 to 95 mm 2. The wire is used in almost all types of installation of lighting and power systems, it can be laid in voids, pipes, steel and plastic trays. Widely used for the installation of switchboards. Well tolerates mechanical damage, vibration and exposure to chemicals. Permissible operating temperature range from -50 to +70, humidity resistance 100% at 35 ° С.
MF 1 the technical characteristics coincide with the previous wire, only lived from copper, so it is more flexible. The minimum core thickness is 0.75 mm 2, the core becomes stranded with 16 mm 2.
In the image: wire MF 3.
MF 3 The characteristics coincide with the previous two wires. Recommended field of application is the installation of lighting and power circuits, where frequent bending of wires is necessary, in switchboards, when installing a large number of electrical devices. It is also used in automotive electrical equipment.
In the image:
PVA copper stranded wire with insulation and PVC sheath, the shell shape is round. The strands are multiwire, their number varies from 2 to 5, cross-section from 0.75 to 16 mm 2. Rated voltage up to 380 V, frequency 50 Hz. The insulation of the cores has different colors, which facilitates installation, the shell is white.
PVS is actively used in everyday life, it makes extensions and cords for any home appliances. It is not easily combustible and retains its characteristics from -25 to +40 ° C. Resistant to bending and withstands at least 3,000 bends.
SHVVP copper or copper-tin plated flat wire, core insulation and PVC sheath, multiwire vein of increased flexibility. Number of cores 2 or 3, section 0,5 - 0,75 mm 2. Voltage up to 380 V, frequency 50 Hz. Used as a cord for household appliances of low power: a mixer, a coffee grinder, a lamp and so on.
Power cables used in private construction
In the image: power cable VVG.
VVG power cable with insulation of conductive copper cores and PVC sheath. Applicable for transmission electric current voltage 600 - 1000 V, the frequency of 50 Hz. Can contain from 1 to 5 cores, cross-sections 1.5 - 240 mm 2. In residential conditions, cables with a cross-section of 1.5 to 16 mm 2 are used. The veins are both single and multiwire.
VVG can be used at temperatures from -50 to +50, it withstands humidity up to 98% at a temperature of 40 ° C, well tolerates aggressive and chemical substances, does not spread combustion. The insulation of the cores has different colors.
There are several types of VVG cable:
AVVG - the characteristics are similar, but veins are used from aluminum, so it is not so flexible;
VVGng - has a shell with low combustibility;
ВВГп - has a flat cable section;
VVGz - the space between the insulation and the shell is filled with PVC or rubber compound.
In the image: NYM power cable, numbers 1 - copper conductor, 2 - PVC insulation, 3 - longitudinal non-flammable sealing, 4 - PVC sheath.
NYM copper power cable with PVC insulation, and the external insulation is made of non-flammable PVC. The internal space between the wires and the external insulation is filled with coated rubber, due to which the cable has increased strength and heat resistance. The strands are stranded and always copper.
The number of cores can be from 2 to 5, a cross section of 1.5 - 16 mm 2. Used for conducting lighting and power cables with voltage up to 660 V. It has high moisture and heat resistance. Can be used outdoors, operating temperature range -40 to +70. There are small disadvantages - the insulation is sensitive to sunlight, so the cable in the open air should be sheltered.
Compared with VVG, the NYM cable is more durable and practical in operation, but it is only of circular cross-section, which sometimes is inconvenient for installation.
In the image: cable KG, in numbers 1 - rubber core, 2 - shell, 1 - insulation.
Cable KG stands for "flexible cable", it can be used for aC voltage up to 660 V and frequency up to 400 Hz or DC voltage up to 1,000 V. Copper conductors flexible or increased flexibility, the number can vary from 1 to 6, insulation - rubber. The outer insulation is made of rubber.
Cable KG can be used at temperatures from -60 to +50 ° C, it is convenient when you need to connect a portable electrical device at the construction site, for example: welding machine, generator, heater, creating temporary conductive lines and so on. There is a kind of KGN with a non-flammable shell.
WBBCs - armored power cable with copper conductors of 1-5, section 1.5 - 240 mm 2, which can be single-wire and multiwire. The insulation of the copper cores, the outer sheath and the space between the strands is made of PVC, then there are 2 layers of metal bands, on top of which are covered with a PVC hose. There is a variant of VBBSHVng with non-flammable PVC.
This cable is used for AC voltage up to 660 V and constant up to 1,000 V. It can be safely laid in the ground, especially by pipes. Operating temperature range -50 to +50 ° С. At a temperature of +35, the moisture content is 98%. Most often it is used for supplying electricity to stationary installations and apartment houses under the ground. There are modifications: AVBBShv - cable with aluminum core, VBBShvng - non-combustible cable, VBBShvng-LS - non-combustible cable with low gas and smoke emission at elevated temperature.
Terms used to describe electrical wires
In the image, the numbers indicate: 1 - three single-wire veins in an additional shell, 2 - a multi-wire vein.
Lived is a metal wire that is the core of any electrical conductor. The core can be monolithic (single-wire) or twisted from thin wires (multiwire). At household electric wires the cross-section of the core is round, for cables, especially large diameter, it can be in the form of a sector. A multi-wire vein is more convenient for installation, as it is easier to bend and easier to install switches, lamps, sockets and so on.
The core can consist of a different metal, in household electrical wires use copper, aluminum and alumina. Aluminum has recently been used less and less often because it is impractical (often breaks on bends) during installation and is not as durable in operation.
Another important characteristic of the core is the cross-sectional area, which is necessarily indicated by the manufacturer and is measured in mm 2. The more electrical appliances in the house and the more powerful they are, the larger the cross-section of the wiring is needed for their safe use. The exact cross-section of the vein necessary for a given house or apartment is usually indicated in the design documentation for the house, if there is no such data, then it is necessary to clarify with the specialist and make a choice with a margin, without saving on it.
Insulation - this material is covered with a vein, it does not conduct an electric current and prevents the propagation of an electric current into the surrounding space. For insulation use a variety of materials - glass, ceramics, but most often different polymers, such as polyvinyl chloride or celluloid. Now, manufacturers use insulation that not only protects the surrounding world from electric current, but also protects the current-carrying vein from the damaging effects of the environment: temperature, humidity, sun, mechanical damage and so on.
Electric wire is one or more insulated conductors that connect the source of the electric current to the consumer. Sometimes on top of the insulation, the wire is covered with a sheath that serves for additional protection against moisture, mechanical damage, corrosive environment and so on. Such a wire is called protected.
In domestic conditions for internal wiring, most often use wires of such brands as PV, PV3, APPV and PPV - they are isolated and not protected
In the image: 1 - metal core, 2 - insulation, 3 - protective shell.
Cable - consists of one or more cores, each of which is enclosed in isolation and all veins are covered with a protective shell of polymeric plastics, rubber or metal. Cables are often used inside the containment, and also various fillers that additionally protect the core from external interference.
Some cables are also protected by a metal winding, then it's an armored cable. Such cables in private construction are used only in individual houses when electricity is supplied underground.
In the image: flexible cord with plug.
Electric cord - a wire consisting of 2 or more, most often 3, stranded flexible wires, each of which is enclosed in an insulation and on top of all the veins are covered with a protective shell of soft plastic or rubber. The cords of the old samples were with an outer shell of synthetic filaments. Such electrical wiring is actively used in household appliances (computer, vacuum cleaner, TV and so on), as they are easy to bend and therefore comfortable. Cords for appliances that need grounding (a kettle, a washing machine, and so on) have 3 cores.
Materials used for conductors of electrical wires
In private construction, wires are used with 3 variants of metal strands.
Aluminum. Positive traits:
1. light and cheap material,
2. Good electrical conductivity, chemically stable.
Negative qualities:
1. an electric wire with an aluminum core quickly breaks on the bends, which often makes it difficult to install,
2. Aluminum is actively oxidized in air to form an oxide, which is a dielectric, and therefore in places of contact it can strongly impede the flow of electric current,
3. Aluminum - a good conductor of electricity, but only when it has a minimum of impurities, which is rare in modern production, focused on reducing the cost of production.
Copper. Positive traits:
1. conductivity is better than aluminum,
2. good flexibility,
3. no oxide film is formed.
Negative qualities:
1. more expensive than aluminum,
2. Specific weight is greater than that of aluminum, this feature is not so important than the previous one,
3. You can not combine copper directly with aluminum.
Alumomed. A mechanical composite consisting of an aluminum core and a copper jacket, which occupies about 10% of the volume of the vein. Combines in itself positive traits aluminum and copper. Features: in all respects inferior to conductors from individual materials and low cost.
Wire cross-section of electric wire
In household electrical wiring, veins with a cross section of 0.25 to 16 mm2 are usually used. Select the thickness of the core first of all from the power of the devices that will be connected to the wire. The table shows recommended values of the cross-section of copper wires depending on the load power.
Dependence of the conductor section of the conductor on the load at a voltage of 220 V
The average value of the total power consumption for household appliances and power tools
| Electrical Appliance | Power, VA | Electrical Appliance | Power, VA | Electrical Appliance | Power, VA |
| boiler | 1200-1500 | grill | 1200-2000 | oven | 1000-2000 |
| a computer | 400-750 | coffee grinder | 800-1500 | heater | 1000-2400 |
| a vacuum cleaner | 400-2000 | radio | 50-250 | Microwave | 1500-2000 |
| TV | 100-400 | toaster | 600-1500 | iron | 500-2000 |
| hair dryer | 450-2000 | fridge | 150-600 | electric lamps | 20-250 |
| electric stove | 1100-6000 | electric kettle | 1000-2000 | fans | 750-17000 |
| drill | 400-800 | compressor | 750-2800 | air conditioning | 1000-3000 |
| water pump | 500-900 | High pressure pump | 2000-2900 | puncher | 600-1400 |
| Saw disk | 750-1600 | Circular saw | 1800-2100 | mowing-machine | 750-2500 |
| Grinder | 650-2200 | electric jigsaw | 250-700 | electric motors | 500-3000 |
| electric hook | 400-1000 | electrical point | 300-1100 |
In domestic conditions it is better to use wires with copper conductors, single-wire and multiwire, they are more convenient in installation and operation and much more durable.
Description of insulation materials used in electric wires
Basic tasks of insulating material:
1. prevention of leakage and destruction of human and animals by electric current,
2. mechanical and thermal protection of the cable,
3. information about the characteristics of the wires.
For household electrical networks now use such types of insulation materials.
Polyvinyl chloride (PVC) - the most popular material for insulation of wires, it is resistant to acids and alkalis, it does not burn, it is soft enough and flexible insulator, so it is easy to use. There are also disadvantages: it loses some of its qualities at a low temperature below -20 ° C, it generates poisonous hydrogen chloride and dioxin when heated.
Rubber - A good insulator for wires is made of artificial or natural rubbers. It makes sense to look for a wire with rubber insulation when you need increased flexibility and frost resistance.
Polyethylene - an insulator that tolerates frosts well and is resistant to aggressive substances.
Silicone Rubber - elastic and the main thing is that the heat-resistant insulator forms a dielectric protective film when exposed to a high temperature.
Impregnated paper - as an insulator it copes with the task perfectly, but it burns, therefore it requires additional protection against fire and high temperature.
Most modern electrical wires are equipped with conductive conductors with different color insulation, which simplifies wiring. For household purposes, three-wire wires are often used, which usually have white, yellow and red color. It is assumed that the wire with white insulation is the phase, red is zero, and with yellow or yellow-green is ground.
Additional articles with useful information
The equipment of electric wires in the country house has a number of features that you need to know about starting this work.
Sometimes there is a need for additional protection of wires with electricity, ignoring this need can not be, because serious troubles are possible.
In fact, all these electrical products are designed to perform a common task: the transmission of electricity from a voltage source to a consumer. They must perform their functions for a long time and reliably without creating emergencies and malfunctions.
Wires and cables work in all branches of human practical activity, when it is necessary to create a closed circuit for the passage of an electric current, to eliminate its losses through unforeseen leaks.
Due to the similarity of the issues to be solved, many ordinary people do not distinguish their differences, they are referred to one category.
However, cables, wires and cords work in different operating conditions, are used in different sections of the electric mains, differ in purpose. Therefore, they have an unequal internal structure and construction.
On electric transmission lines, there are cases when electricity is transmitted sequentially through air wires and cable, as shown in the photo below.
A cable branch on an overhead power line is created to perform specific tasks required by local conditions.
Electric wire
Composition
It has the simplest design, consisting of two parts:
1. a metal core, serving to create an electric current path;
2. The insulation layer, which prevents the flow of currents in the undesirable direction.
Isolation functions can be entrusted to air surrounding the metal, rather than to a special shell of polymers and dielectrics. In this case, the wire strand is made bare, and the places of the wire contacts with the fastening elements to the supporting structures are created with dielectric properties. They are called insulators.
Materials for a current-carrying vein often create on the basis of:
copper and its alloys;
aluminum.
A promising design is the composite, created to effectively use the best performance characteristics of the above metals.
To solve specific problems, conductive strands of steel alloys, nichrome, other metals and even silver or gold can be used.
Core construction
It can be created from:
1. a solid conductor of a certain length;
2. or wiggle out of thin wires running in parallel. Single-wire wires are easier to manufacture. They are the most rigid, they are used for transmission of electric energy with stationary fastening, the constant and low-frequency currents transmit well.
Multi-wire veins are more flexible, better operate at high frequencies.
Usually the term wire refers to a product from one wire. In fact, they can be twisted or mounted with several cores. Examples can serve, dual telephone wires such as "noodles" and other structures.
All of them are designed for operation under light operating conditions and in most cases require additional mechanical protection against external influences.
Electrical cable
Its more complex design is created to ensure reliable operation under the influence of destructive environmental factors.
The number of conductors is determined by the operating conditions. They are isolated among themselves by various dielectric layers. Additional cable elements can be:
protective outer shell of plastic, steel or wire armor;
aggregate;
core;
Each of these parts performs protective functions for specific conditions.
The main groups of cables for electricians are:
power, working in electrical installations up to and more than 1000 volts;
control, transmitting information about the status of various elements of the system;
controls used for the transmission of commands entered manually or by automatic systems;
communications based on the exchange of signals of different frequencies.
A separate group includes cables for special purposes:
radiating, used for transmission of high-frequency radio signals;
heating, transforming electric power in the thermal one.
Current-carrying conductors
They are made according to the same principles as the wires. Can be created from different materials by a multiwire or solid conductor. Covered by a dielectric layer.
In terms of the degree of flexibility of the design, the cables are divided into seven groups. To the hard-bending category No. 1 is the monogram. The most flexible and correspondingly expensive is # 7.
Stranded wires flexible cables When mounted, connect through special tubular tips, called the end-users. They do not need to be installed on the monogram.
Shell
Protects current-conducting veins and their isolation from mechanical damage, it seals them against penetration of moisture, foreign impurities. May contain reinforcing and shielding layers.
Shell materials most often serve:
reinforced varieties of rubber;
plastics;
Plastic materials can perform the following tasks:
1. provide an insulating layer with high dielectric properties;
2. create a sealed hose that protects the structure placed in it;
3. serve as a screen due to the use of semiconductor properties.
Impregnated cable paper is used in high-voltage products up to 35 kV inclusive.
Cross-linked polyethylene is used to provide dielectric properties of cables operating in electrical installations with voltages up to 500 kV with high reliability and durability.
For high-voltage circuits 110 ÷ 500 kV inclusive, until 2005, oil-filled cables were produced, consisting of shielded conductors mounted inside a sealed shell with oil. With the massive introduction of insulation based on cross-linked polyethylene, their design has lost its relevance.
Safe work conditions
All products from the cable are evaluated for:
1. Behavior at short circuit in the cable channel;
2. the ability to withstand prolonged overloads;
3. spreading of open fire at high heating;
4. Detection of toxins during burning.
Danger of faults
When the conductor is closed, a temperature of up to a thousand degrees is created. It is transmitted to nearby cables with small losses, warms them up, is able to engage in burning. The resulting gases create high pressure, which depressurizes the cable duct, ensures the flow of fresh air with oxygen, which supports the development of the fire.
Prolonged overloads
Excess currents heat metal conductor veins and a layer of insulation with a sheath. Under the influence of the limiting temperature, chemical reactions occur in the decomposition of the insulation layer, gases are released. Their mixing with air and ignition begins.
Propagation of combustion
The usual shell of PVC-plastics and certain types of polyethylene is capable of transferring the burning process further, which contributes to the development of fires. A special danger is created when the cables are positioned vertically.
For this indicator cable production is divided into:
not spreading combustion in a single gasket: vertically and horizontally;
not spreading combustion in a group gasket: vertically and horizontally;
fireproof.
The main indicator of this process is the specific heat of combustion of the electrical wiring or cable line, determined experimentally.
Ability to excrete toxic substances
Here, the reaction of the cable jacket to an external fire affecting its structure is taken into account. Compositions of insulation that do not even spread combustion can release dangerous toxins with significant heating.
Such cables are forbidden to use in places with a mass congestion of people on the transport of subways and similar facilities.
Requirements for cable products
To improve operational reliability and safety, modern cables are evaluated by:
fire resistance;
resistance to heating of the dielectric and fire resistance;
ways of cutting ends - endings;
protection from moisture penetration.
Each of these parameters has analysis techniques and criteria for evaluating the results.
Electric cord
Its design takes up something in between the electrical wire in the insulation of several cores and the cable. It is created by special technological methods for giving the properties of increased flexibility, ensuring long-term operation when creating frequent, numerous bends.
The purpose of the electric cord: providing connections of the voltage source with mobile electrical appliances.
In everyday life an electric cord is installed on table lamps and sconces, irons, kettles, and other similar consumers.
Household and professional power tools are also connected in the same way.
But, in the technical literature it is customary to call such a design a power cable, which more accurately reflects the principle of its operation.
Ways of marking
Cables and wires must be distinguished when buying or selling and during operation. To this end, they are labeled:
at the factory;
when installed in an electrical installation.
Factory markings include:
color marking of the insulating layer of conductors;
writing inscriptions on shells with letters and numbers;
hanging tags or labels.
It allows you to:
determine the purpose and design features of cable products;
analyze the technical characteristics of a particular model;
to evaluate the possibility of using it in the concrete operating conditions of the electrical installation.
The operational marking complements the factory information and is carried out by drawing inscriptions and tags indicating the circuit designations and routes of laying both the whole cable and the separate vein between the electrotechnical elements. It can be complemented by the inclusion of electronic markers providing information on its characteristics. This allows you to reliably calculate it even in a filled cable channel among similar models.
Color identification of conductor insulation in Russia
The dielectric sheath of the wire can be painted:
along the entire length of solid color;
drawing of color marks.
GOST 28763 defines the rule to use markup only with the following colors: white, turquoise, yellow, green, brown, red, orange, pink, light blue, gray, purple and black.
And for yellow and green colors only their combined combination on one shell is allowed. To use them separately is prohibited. This coloring is for.
To select a neutral or medium conductor, use a light blue color. Phase conductors are usually denoted by black, brown and gray.
The exemplary marking methods reflect the principles for determining the design of cables and wires. But, they do not contain a complete list of all the information about them, which are published in special directories in detail.