The main materials for production of wires and cables are copper and aluminum. Most of the electrical wiring in houses built in Soviet times, implemented using aluminum conductors. At present, the overhaul of the electric enterprise or the installation of new wiring use only copper cable. What is the reason? What's wrong with aluminum?
Positive properties of aluminum are its lightness and relatively low cost in comparison with copper. The list of advantages ends.
Aluminum has a higher resistivity than copper, therefore, to ensure the same conductivity required aluminum wire of larger diameter and cross section. A thin film of oxide formed on the surface of aluminum conductor, a poor conductor of electricity, so good contact is not necessary.
Another disadvantage of aluminum conductors is manifested in their fastening with screw clamps. Due to the low yield strength aluminium "flows" and slipping out of the clamp, significantly weakening the connection. Aluminum is a brittle metal, aluminum conductor after a two - or three-fold flexion and extension is simply broken. Contacting with copper, aluminum forms a galvanic couple, in which electrical corrosion is destroyed, impairing the quality of the connection or bringing it to nothing.
The above disadvantages are not conductors of copper, but because almost all wiring is done with the use of copper wires and cables.
Marking of wires and cables
Alphanumeric markings applied to the outside insulation of the cable and carries information about the material lived, their number and section, the type of inner and outer insulation, flexibility, Flammability, and other properties.
The first letter in the marking of the cable means that its conductive core is made of aluminum. In the absence of the letter A at the beginning of the marking wire can with 100% certainty that it is copper.
The following letter also is not so simple. If it is the cable, refer to the marking
will be missing. On the same wire or cord will reveal the presence of the letters P or W, respectively.
Even one letter. For aluminum wires, it will be the third, for aluminum cables is second, and copper – and do first. It denotes the material of insulation: B – impregnated paper, polyvinyl chloride, P – plastic, R – rubber.
Wire with rubber insulation often protect extra shell, as always reported, adding the letter for polyvinyl chloride (In) or Naira (N).
The last letter will indicate the presence and properties of the protective screen:
This is followed by the symbol. About the material of the protective shell will report the following notation: G – flexible wire without protection, B –armour of steel tape, To – armor of round steel wires, winding of yarn, Seam – PVC hose, SHP – plastic hose, the e – screen.
Digital signs are most often used two groups of digits, separated with an "X", the first group indicates the number of wires, the second is their cross-section.
For example, labeling PVA 3X2,5 uniquely identifies a three-core power cord with copper conductors of 2.5 mm2, protected by PVC isolation.
Not always and not everywhere in the marking of cable products are used absolutely all the groups of symbols, many of them are just down.
the Most used types of cable products
Copper flat wire extra-flexible with sheath and insulation of polyvinylchloride. Used as connecting wire for household appliances and lighting. For arranging the transaction
Copper round solid conductors with PVC insulation. Widely used in the installation of switchboards. АПВ1 – full analogue with the conductor made of aluminum
Copper flat wire with 2 or 3 single conductors in PVC insulation with separating webs. It is used for laying power lines and the installation of permanent lighting systems. APPV – full analogue with the conductor made of aluminum
Multicore flexible copper power wire with double insulation of PVC plastic. Used when constructing the wiring and connection of domestic electric tools and appliances
Copper cable flexible or extra-flexible with rubber insulation and rubber sheath. Used to connect portable devices
Copper power cable with insulation and sheath of PVC. Strong to break and bend. Used for arrangement of electrical wiring
Imported analog cable VVG. Different additional intermediate insulation layer of coated rubber. As VVG, used for furnishing power and lighting networks. The disadvantage is unstable to ultraviolet radiation
Let a your home electrical wiring serves long and reliably. Good luck to you!