In industrial and domestic purposes to create power and lighting networks are increasingly used cable NYM. This high-quality German product, which comes from Europe, as well as produced in Russia. The closest domestic analogue is the VVG cable.
This cable is made by German technology and is characterized by the presence of copper conductors and high-quality plastic insulation, which does not support combustion.
Table of contents
Deciphering of NYM cable
The range of wire and cable products is very large. That's why special markings are used for systematization. In the case of cable NYM deciphering of each letter is as follows:
- N is a sign of the German standard (Normenleitung), indicating that the product has passed a number of tests and by its parameters correspond to the declared characteristics. Included with NYM power cable there is always a certificate of compliance with international quality standards.
- Y means that polyvinyl chloride (PVC) is used to manufacture the insulation. The peculiarity of this material is moisture resistance and no reaction with acids, alcohols, gasoline, various gases.
- M means a protective sheath designed for small deformations. Which makes the electrical cable NYM suitable for installation work.
On the sheath there may be the inscription VDE. This is an abbreviation of the Association of German Electrical Engineers (Verband Deutscher Elektrotechniker). The VDE marking informs that the sheath does not support combustion, it is allowed to use in fire-hazardous areas and the product complies with all international standards.
The marking of NYM electric cable depends on the presence of earthing and may contain the symbol J or O. In this case, the symbol O in the marking may not be specified, as it informs only about the absence of the wire intended to connect the ground. The J symbol indicates the presence of such a conductor and is therefore always indicated.
NYM-J cable is characterized by a yellow-green protective grounding conductor. The filling can be made of thermoplastic elastomer, unvulcanized rubber or highly filled plastic compound. This insulation eliminates the formation of cracks in operation, increases flexibility, gives the correct circular shape.
To the marking may be added a prefix OZH. It means that the cores used are single-wire, and therefore less flexible than multi-wire.
Thus, the manufacturer puts all the necessary information in the name of the wire NYM, the description of which contains information about the properties of the sheath, the number of wires and cross section.
For example, the designation NYM-J 3x3,5-0,88 means that it is a standard electrical cable with an outer sheath of PVC, three 3.5 mm² cross section conductors at 0.88 kV and grounding.
Fields of application
According to the marking, NUM wires are recommended for indoor single stationary installation only. Without additional protection, bundling is prohibited.
Outdoor use of the cable is not recommended due to the fact that PVC is destroyed by ultraviolet radiation present in sunlight. If it is necessary to pull the wire outdoors, it should be enclosed in a steel or plastic box. It is also not recommended to lay the wire in fresh concrete.
Installation is governed by the manufacturer's recommendations and electrical and fire safety standards. The use of such electrical cables is possible in any electrical installation work. Even in buildings with the first class of electrical safety and in explosive zones V1b, V1g, VPa.
NYM is used for laying under plaster, in concrete masonry, in the channels of wall panels, in specialized pipes and ducts.
There are a number of restrictions for use in natural wood houses. Open laying is carried out only in pipes and ducts, and inside wooden walls laying is possible only in metal pipes.
NYM cable construction
Conductor in the cable is made exclusively of copper and comes in single wire or multi-wire. Covered with PVC-plastic of different colors in accordance with current standards.
Possible number of conductors - from 1 to 5. The number depends on the cross section of the conductors.
The intermediate insulation of the cable consists of a mixture of rubber and chalk. It acts as a dielectric and does not support combustion.
Outer sheath is made of durable PVC-plastic of light gray color, which does not support combustion.
Technical characteristics of NYM cable
International standards define the following technical characteristics:
- Temperature range: -50...+50°C.
- Laying temperature: not lower than -5°C.
- Limitation of bending radius: minimum 4 diameters.
- Warranty period: 5 years.
- Service life: up to 30 years.
- Cross-sectional range of copper conductors: 1.5 - 35 mm².
Electric cable can be made: according to German standards, GOST, TU. The manufacturer itself determines the specifications. For this reason, some manufacturers of NYM cable technical specifications may differ from the standard.
