Optimized design of multiple-supply service trench

Two different standardized trench layouts, containing, gas and water pipelines, telephone cables, 1-kV and 10kV-cables (LV and MV-cables), so-called multiple-supply service trenches, were analyzed with respect to their thermal loading. In principle, two different options were regarded, i.e. with currents in the cables according to VDE 0276 part 1000 and based on the current obtained for the maximal permissible temperature of the cable conductor as determined by the calculating program. The calculations according standard loading conditions resulted for realistic thermal soil conditions (λ = 1.5Km/W; ϑ_soil = 15 C) in a maximal temperature of the water pipe of 20.1 C assuming a water temperature of 18 C. In case of the worst conditions i.e. λ = 1.5Km/W; ϑ_soil = 15 C the maximal temperature for the water pipe will increase up to 21.5 C.