The VVG-ng cable is a representative of a fairly wide group of conductive products used to provide electricity production shops and offices, for laying in walls, pipes and tunnels, for street lighting. Any electrical work in the construction of private housing or multi-storey buildings require the use of this type of material. The VVG-ng cable is designed for laying in places where it is necessary to avoid fire. It consists of conductive copper filaments enclosed in an insulating sheath and covered with a common film on top. All cable components are designed to continue delivering electricity to its intended destination in the event of a fire.
Types of VVG-ng cable and its marking
Products marked VVG-ng include several types of cable that differ in their characteristics. In order to distinguish each of them, a marking was invented, including information on the composition of the conductive thread and its cross section, on the insulating sheath and its properties, and on the features of the cable.
So, the abbreviation VVG-ng means:
- Thread material - copper (by default). If the thread is aluminum, then the letter A (AVVG) is in front of the designation
- BB - means that PVC compound was used to insulate copper threads and the outer sheath of the cable
- G - means "naked". The cable does not have a protective coating in the form metal plate or other material. Such protection is present in products with a larger cross section.
- ng - means "non-combustible", does not spread combustion when laid alone and in a group. Cable manufacturing technology helps to limit its ignition. Such a cable does not burn in a fire, but melts.
When designating products, other signs can also be used:
- VVG-ng-LS - cable has low smoke emission (LS)
- VVG-ng-NF - cable insulation does not contain halogen materials (NF)
- VVG-ng-P - the cable has a flat shape and can be used for laying under plaster (P), it is fire resistant
- VVG-ng-FRLS - the cable is fire resistant (FRLS) and in the event of a fire will continue to supply electricity for a certain time (usually 60-180 minutes)
Along with letter designations, numbers are used for cable marking. They reflect the number of copper threads and the cross-sectional area of one thread in square millimeters:
- Marking VVG-ng-LS 3 x 50 + 1 x 25 means that the cable has two sheaths made of PVC plastic (copper strands sheath and a common outer sheath - VV), has no protection (G), has low flammability (ng) and low emission smoke (LS). The number of copper threads is 3 with a section of 50 mm (3x50), and one thread has a section of 25 mm (1x25)
The marking also includes the operating voltage of the cable. It is indicated in kilowatts, for example:
- VVG-ng-LS 3 x 50 + 1 x 25 -1 operating voltage of this cable is 1 kV (number 1 in the marking)
The VVG-ng cable is a universal conductive product used in wet conditions and at altitudes up to 4300 meters. Application temperature ranges from +50 to -50°C, maximum allowable humidity - 98% (at +40°C).
To connect any electrical equipment at work or at home, you need a wire corresponding to the expected load section. Most commonly used VVG cable, the use of which is possible in an open and closed way of laying.
This cable has several types of marking, the decoding of which indicates the version. Consider the main symbols and technical characteristics that the wire of this brand has.
Cable types
It will be useful for novice electricians to find out what varieties the wire of the VVG brand has, and what is the decoding of the marking:
- The standard version of VVG is double PVC insulation, which does not have additional protective characteristics;
- The protective winding of the VVGng wire is made of non-combustible PVC material;
- The use of halogen-free PVC as insulation gives the VVG cable with the additional abbreviation ng-ls such a property as smokeless melting or burning. Recommended for use in in public places where there is a high probability of poisoning people;
- For laying in conditions with a high risk of fire, the use of a cable marked ng-frls is prescribed. This type of electrical wiring is fire resistant, and does not smoke when ignited. Asphyxiating gases are also not emitted.
This type of wire is used for open mounting or in closed channels in places with increased fire safety requirements.
The most commonly used type of wire is VVGng - the technical characteristics and reasonable price make this type of electrical cable the best option in any field. It can be used not only in wooden buildings but also in wet conditions.
Cable marking designation
Now let's look at what the abbreviation means, which is applied to the VVG cable. Decryption symbols allows you to easily determine all the properties and technical characteristics that this wire possesses.
If the conductors of the cable are made of aluminum, the letter (A) is placed in front of all designations. For copper wires, the additional designation does not apply.
The insulation material of conductive conductors has the following designation:
- P - insulation made of polymeric materials;
- B - polyvinyl chloride;
- Pv - material based on polyethylene.
Deciphering the following marking letter allows you to find out what the cable sheath is made of:
- B - PVC outer sheath;
- Shv - a protective sheath in the form of a hose;
- P - the wire has a polymer outer insulation;
- Shp - external insulation made of polyethylene hose.
Also, any wire has letter designation degrees of protection:
- B - armored;
- D - there is no additional protection, the cable belongs to the category of flexible products.
Fire safety marking
Separately, the marking indicating the category of fire safety of the cable is considered. Deciphering this abbreviation will allow you to determine which group the wire belongs to and where it can be installed:
- ng - this wire does not support open combustion;
- ng-ls - cable with low smoke emission during the melting of insulating materials;
- ng-hf - when melting the wiring, there is no emission of gases that cause corrosion;
- ng-frls - the wire does not support open combustion, and when melted, it emits a minimum content of smoke and gas;
- ng-frhf - this cable has all the protective properties of previous types of wiring.
Note! All products marked ng are intended for group laying. A wire without such an abbreviation is designed for single laying in closed strobes.
In addition, it should be noted that the VVG cable most often has a round cross-section of conductive cores: it is more convenient to use and suitable for widespread use in everyday life or production. Sometimes there is a cable with additional markings in the form of a small letter "p". This means that the conductors have a flat cross section. As a rule, such conductors are designed for high power and are used in industry.
Main characteristics
Now consider the main technical characteristics that the electrical wire has.
Design
The main criterion for the design features of the cable is the number of cores through which the current passes. Depending on the purpose, these veins can be from two to five. In addition, the cores can be made from one (monolithic) wire or from several thin wires twisted together.
The insulation of each conductor is made in different colors, in accordance with international requirements. If there is a grounding conductor, it is indicated by multi-colored insulation and may have a smaller cross section.
As already noted, the most popular cable with a round cross section. But products are also produced that have a sector (flattened or oval), as well as a flat shape of conductive wires.
Cross section of conductors
The cross section of the cores is 1.5–240 mm 2. Here is the recommended cross section for domestic purposes:
- For the lighting circuit, a 1.5 mm 2 wire is used;
- For connecting sockets - at least 2.5 mm 2;
- With a separate connection of powerful consumers (boilers, electric furnaces), it is recommended to use a VVG cable with a conductor cross section of 4 mm 2.
Note! The weight of the cable depends on the cross-section of the cores, the material of the braid and the degree of armor. The mass of 1 km of wire is taken as a basis and varies from 28.5 kg to 10.25 tons.
Operational and technical characteristics
Consider the main indicators that are inherent in the VVG cable:
- Electric current frequency: 50 Hz;
- Permissible voltage - 220, 660 and 1000V;
- The maximum operating temperature is 70 °C. The insulation is able to withstand short-term (4 seconds) heating up to 250 °C during a short circuit;
- Operating conditions are considered to be temperatures from -50 to +50 ° C, relative humidity - up to 98%;
- The insulation resistance is calculated for an operating temperature of 20 °C and depends on the diameter of the conductors: with a cross section of 1.5 mm2, it is 12 MΩ/km. If the cross section is more than 10 mm 2, the calculated resistance will be 0.005 MΩ / km;
- The service life of the cable is 30 years. The warranty is provided for 5 years, and if the wire is not properly stored, it is reduced to two years.
Properly store the cable on wooden spools in indoors. In this case, the coils can be both open and closed. When storing reels under a canopy, they are covered with wooden shields!
Laying methods
There are two ways to lay an electrical wire like VVG: open and hidden.
public method
The VVG cable has technical characteristics that allow its open laying on a non-combustible base (concrete, gypsum, brick and other materials).
Also, the cable is laid in a suspended way: on poles, supports, etc. In this case, to prevent stretching under its own weight, steel wire reinforcement (the so-called wire rod) is used. It is practiced to lay a cable inside a metal or corrugated pipe.
Hidden laying method
This method is used in residential areas. The best option is to install electrical wiring before applying a layer of plaster on the walls. With already plastered surfaces, it is required to punch strobes for laying the wire. With this method, mechanical damage is unlikely.
For concealed wiring in wooden or frame houses apply corrugated pipes, inside which the wiring is placed. This significantly increases the fire safety of electrical wiring and the building as a whole.
underground installation
It is forbidden to lay the VVG cable in the ground without additional protection. Sealed boxes, flyovers, pipes, and so on are used as protective structures.
In conclusion, let's say a few words about the manufacturers that produce these products. Almost every plant cable products produces wire brand VVG: it is in demand. Electricians have no complaints about the products of such manufacturers as Moskabel, Energokabel, Sevkabel. We also note that the products of these particular factories are counterfeited most often, so purchase an electrical wire at trusted outlets.
Wire and cable VVGng LS is the top of the family of cable products with the abbreviation VVG, the secret of its privilege is the postscript LS, what it indicates and what it hides, we will analyze in detail in this article.
Smoke in the premises is considered the most important factor that increases the risk of negative consequences in case of fire. In the event of a fire at industrial facilities and large public buildings, cable routes become one of the main sources of smoke. The sad experience of the Ostankino television tower, the Manege and other disasters of the last decade only confirmed this truth.
Currently, technical regulation documents strictly regulate the types of cable products that can be used for group laying inside public and industrial premises (GOST R 5315-2009). Here, in addition to the condition of non-proliferation of combustion (-ng), one of the mandatory requirements was low smoke and gas emission during combustion or smoldering of the cable.
Designation LS, order of assignment
The decoding of VVGng LS is as follows:
- There is no letter A at the beginning of the marking, which means the cable is copper;
- B - the outer insulating layer consists of PVC insulation;
- B - core insulation consists of PVC insulation;
- ng - does not spread combustion with single and group laying;
- LS- L ow S moke (translated from English light smoke)
In the marking VVGng (..)-LS, after the category through a hyphen is the designation LS, indicating low smoke and gas emission ( L ow S moke). Of course, such an index can be assigned to a cable only in case of a successful test for such an indicator. The standard test procedure for smoke generation during combustion and smoldering, installation description, etc. are given in GOST R IEC 61034 -1 (2) -2005.
The principle of the test is to measure the transparency of the air in the chamber with the cable before and after combustion. The smoke resulting from the combustion of the sample reduces the light transmission of the volume, which is recorded by the instruments. The result of the test will be the ratio of light transmission before and after the experiment, expressed as a percentage. In accordance with GOST R 53769-2010, it is considered that the cable has successfully passed the test if the smoke has reduced transparency by no more than 40%. In this case, the manufacturer has the right to put the LS index in the marking.
Cable insulation with low smoke emission
For the production of VVGng LS cable, PVC compounds of reduced fire hazard are required, and, in contact with fire, they should not produce a large amount of smoke. In addition, it is required that the smoke be minimally toxic (the toxicity index is not more than 40 mg / m 3 according to GOST R 53769-2010).
The task is difficult, but it was successfully solved by selecting special additives - antipyrines and additives. Today, such plastic compounds are produced both in Russia and abroad. Domestic manufacturers have registered several TUs, for example TU 2246-001-25795756-2009, and produce plastic compounds based on them, specialized for core insulation, internal filling and outer sheath (grades PPI 30-30, PPV-28, PPO30-35, respectively).
Cable structure VVGng LS
The composition and arrangement of the elements of the VVGng (..) -LS cable is no different from its counterparts - cables with copper conductors, with PVC insulation and sheath according to GOST 53769-2010. External similarity is clearly visible in the image shown in this section.
The VVGng(..)-LS cable can be round or flat, the maximum number of cores is five. The cores themselves can be single-wire or multi-wire, round or sector. The nominal values of the cross-sectional areas are selected from a single standard series for all.
VVGng LS cable specifications
Since the characteristics of the entire family of cables with PVC core insulation and sheath are standardized by one standard GOSTR 53769-2010, they vary only within small limits for different manufacturers. The standard does not introduce separate indicators for the cross-sections and shape of the cores, the thickness of the insulation of conductors and the sheath, electrical resistance etc. for cables with plastic insulation with reduced smoke formation. They go along with the whole family of PVC compounds. Separate values are given for XLPE insulation, etc.
GOSTR 53769-2010 provides for -LS products some difference in minimum tensile strength, it may be less than that of VVG, but does not differ from VVGng. Therefore, the section "VVGng LS cable specifications" in terms of general characteristics practically does not differ from the section of the same name in the article cable brand VVG. Acquainted with general characteristics VVGng(..)-LS is possible.
Application of cable VVGng(..)-LS
Cables VVGng - LS related to fire hazard classes P1.8.2.1.2 and
P1.8.2.2.2 can be used for group laying in residential and public buildings, internal and external cable structures at industrial enterprises. It is allowed to use the cable at nuclear facilities.
Other cable options
- - round copper wire with PVC insulation of the outer and inner layers, has low gas and smoke emission during combustion in single and group laying;
- VVG-P - the same as VVG, but flat design;
- - round copper wire with PVC insulation of the outer and inner layers, has low gas and smoke emission during combustion with a single laying;
- VVGng-P - the same as VVGng, but flat design;
- VVGng-ls - round copper wire with PVC insulation of the outer and inner layers, has low gas and smoke emission during combustion in single and group laying;
- VVGng-Pls - the same as VVG-ls, but flat design;
- VVGng-frls - round copper wire with fire-resistant PVC insulation of the outer and inner layers, has low gas and smoke emission during combustion in single and group laying;
- VVGng-Pfrls - the same as VVGng-frls, but flat design.
Which does not spread combustion. In short, VVGng decoding indicates this property with the last letters "ng". Such a wire is usually used in the distribution of electricity or its transmission. Because of this feature cable VVGng 3x1.5 , great for laying in bundles. Its almost complete versatility makes it possible to use in different climatic conditions - from frosty northern to hot tropical climates. This cable is most often used where there is a high risk of fire - enterprises that work with explosive or combustible components.
VVGng (a) transcript
According to the marking, we can understand what kind of cable it is. "VVG" stands for "vinyl-vinyl-naked", thereby indicating that the cable has 2 layers of polyvinyl chloride in its structure, with no armor. About what "NG" means, it was said at the beginning of the article. "A", which is usually indicated in brackets, means the GOST type of flame retardance.
Even when laying cables in bundles, in the event of a fire, burning will not spread to other wires. Ordinary VVGs cannot boast of such a property, except for solo editing. One small clarification: do not confuse the letter "a", which is placed before the abbreviation - this means that the wire is aluminum. In our case, copper. As you can see, there is nothing difficult in remembering the decoding of the VVGng cable.
Laying methods
Open gasket. Based specifications, the cable can be laid on structures, as well as surfaces that are not combustible. It can be concrete, brick, plastered surface, etc. Laying is also provided for suspended structures, such as a cable, but it is necessary to exclude stretching or sagging of the wire.
Protection pad. If there is a significant threat of mechanical damage to the wire, then it is necessary to provide a protective case, for example:
- pipe;
- cable channel;
- corrugated sleeve;
- metal hose, etc.
Hidden. Laying is carried out under plaster, in voids or in specially made furrows. In this case, mechanical damage is unlikely, however, the voids of wooden houses fall into the exceptions. In such cases, it is necessary to carry out installation in non-combustible cases such as pipes.
In the ground The rules do not include laying a cable without special protection, because the wire has no armor. Installation of the wire in such cases is carried out in sealed cases (boxes) along overpasses and cable structures.
