Installation cables are used for laying installations supplying electricity from the grid. Cables to be used indoors have copper or, rarely, aluminium cores with cross-sections of 0.5 to 300mm².
The following rated voltages are available:
Installation cables comprise cores, in the form of wires or strands. Each core is insulated separately, and together they are covered with a layer of rubber, vinyl, or PVC. Cores in installation cables for permanent mounting are wires, whereas for mobile loads multiwire strands are used. Installation wires may be flat or round.
For installation cables, a high standardization of available versions, materials, markings or even sheath colours is applied.
The symbol comprises letters and numbers describing:
Two digits describe permitted voltage and the number and cross-section of the cores.
H – harmonized type,
05 – rated voltage: 300/500 V,
V – external insulation material: polyvinyl chrolide (PVC),
K – core structure: multiwire, flexible, for permanent laying (class 5).
Specific markings can be used by some manufacturers.
There are also norms for sheath colours of particular cores, e.g. the PE cable is always green and yellow, whereas the neutral cable is always blue.
Normalization ensures the possibility of using a different cable from a different supplier, as long as its markings match.
Detailed and complex marking system is a result of a large variety (several dozen types) of cables for electrical installations available on the market and manufactured by various suppliers.
Installation cables are frequently used by people unaware of the risks connected with improper usage of a particular cable. Operational safety of electrical installations, i.e. protection against electrocution or combustion, as well as durability, is ensured by complex regulations and norms that describe possible applications of particular cables.