Direct burial of unarmored MV cables 2

[Power0020]

I am designing 33 kV cabling system in a wind farm, can I go for direct burial of single core cables (unarmoured) without pipes? using fine sand as a back-fill and protective tiles?

any IEC reference?

 

[7anoter4]

I don’t think such IEC standard exists. Usually there are national [regional or per utility] standard for installation purpose. For instance:
-IEEE Std 525-1992, IEEE Guide for the Design and Installation of Cable Systems in Substations. ch.13.1 Direct burial
By the way, here it is mentioned as follows:
"This system has low initial cost, but does not lend itself to changes or additions, and provides limited protection against the environment. Damage to cables is more difficult to locate and repair in a direct burial system than in a permanent trench system."
-National Electrical Safety Code (NESC) /2007 Section 35.Direct-buried cable
-US AIR FORCE

http://armypubs.army.mil/eng/DR_pubs/dr_a/pdf/tm5_811_1.pdf

CH.7-5. Direct-Burial Cable Installations.
-U.K. DEFENCE ESTATES MINISTRY OF DEFENCE Specification 034 Electrical Installations. SECTION SIX - CABLE INSTALLATION
-DIN/VDE 0289 ,100,101

 

[Marmite]

Whether you can or can't lay the cables direct depends entirely on local codes and legislation. Utilities in the UK use unarmoured 33kV cables routinely. The cables are generally single core polymeric with a copper wire screen. However the legislation requires them to be marked and protected, which if laid direct would mean sanded as you describe, and covered with cable tiles which these days are made of recycled plastic rather than concrete.

Regards
Marmite