In places where acids and alkalies are present, the type of wiring used is
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In the field of insulated cables, PVC cables have occupied an important place and in fact, these are most popularly used in homes for domestic wiring. Various types of PVC cables are available, e.g., cables for control, signaling, instrumentation, rural electrification, and house wiring, communication as well as for use in wires, automobiles, T.V. electric welding, etc. These cables are suitable where the wire temperature during use does not exceed 70°C. Polyvinyl chloride (PVC) cables are used for the low and medium-voltage distribution systems. They are usually of two grades viz., 250/440 volts grade cable and 640 ⁄ 1100 volts grade cable. The conductors used in these cables are also of stranded aluminum or copper wires which are separately insulated with PVC insulation.
Wiring with PVC sheathed cables is installed directly in underexposed conditions of sun and rain or in damp places. This system of wiring is suitable in situations where acids and alkalis are likely to be present. Where attack from white ants (termite) is prevalent, anti-termite treatment should be given. In cases where there are chances of any damage to the wirings, they should be covered with sheet metal protective covering. The base of the covering is made flush with plaster or brickwork.
PVC cables are more flexible, non-draining, and have the following properties.
- High mechanical strength
- High resistance to abrasion
- High fire resistance at high temperature
- High resistance to acid, oil, and chemical fumes
- High dielectric strength and high insulation resistance even when dipped in water
- High aging property
- High corrosion resistance and can be laid directly underground in places where the soil is of active nature