Laying instructions of power cables

Undermentioned instructions are valid for power cables up to nominal voltage of 36 kV. These cables are suitable for installation indoors, outdoors, for direct burial in earth, in water or in concrete.

During installation of power cables must be kept following guides:

• protection against direct sun irradiation
• laying on solid, smooth and free of stones ground or bedding in sand or stone-free soil
• protection against mechanical demage
• protection against chemical and thermic influence
• all turns of the installation line shall be well shaped and equipped with rolls
• must be kept the bending radius of cable and installation temperature (see data sheats of cables)

The maximum permitted pulling force during installation is: P = A . σ [N] where: A the sum of the cross-section[mm²] of all conductors, shielding and concentric conductor is not included,

• σ = 50 N/mm² for cables with copper conductors,
• σ = 30 N/mm² for cables with aluminium conductors

The minimum bending radius of single core cables may not be smaller than 15x diameter of cable.

The minimum bending radius of multicore cables may not be smaller than 12x diameter of cable.

The minimum installation temperature for cables is -5 °C. The minimum installation temperature for armoured cables is 0 °C. This value refers to the cable temperature, not the environmental temperature.

Underground cables may not be buried less than 0,6 m under the surface, the depth of cables under roadways not less than 0,8 m.