These wires are used for general usages as in dry rooms, electrical equipment, keys and panelboards, and also inside the pipes under plaster, which are molded by insulating clamps; up to 750-v voltages are also used. Using these types of wire is not allowed directly below the plaster.
There is another type of wire called insulated or Stranded annealed copper; Stranded plain annealed copper wire (cable) is not actually single-stranded and is composed of twisted rods. Therefore, this group of wires can be categorized as the insulated wires (Flexible) and the rod. The minimum diameter of twisted rods in Stranded plain annealed copper cable (wire) starts from 1.04 for size 6 and varies up to 2.85 for size 400. (This item is between 0.25- and 0.5-mm square in insulated wire or cable).
Whenever the diameter of one of inner strands of the cable is between 0.25 to 0.5 mm, and it is also made of the sum of these conductors besides the desired segments, we can call this conductor an insulated one. For example, by placing 30 conductors with a diameter of 0.25 mm next to each other (with a layer of covering around them – insulation), an insulated wire (flexible) with a nominal cross-sectional area of 1.5 mm square will be made. As it has been mentioned before, this also applies to insulated cable, for example, by placing 765 conductors with a diameter of 0.5 mm square next to each other (with two layers of cover – insulation – jacket), an insulated cable with a nominal cross-sectional area of 150 mm square will be made.