I have 2no parallel 4-core 400mm2 XLPE SWA cables laid in pvc ducts directly in the ground. They run some 90m with a load which ranges between 780A to 1230A, the latter becoming more common for longer periods due to the addition of recently installed plant. I am not sure of the cable manufacturer, nor indeed if they are XLPE as the glands are made into the bottom of the switchboards. The installing sparks must have been super nimble contortionists! Anyway, I am seeking an approximate current carrying capacity for the method of installation. I believe the cables are under sized although not showing any signs of undue degradation. The Flir shows them around 100C at one end.
The buried rating will depend on the make up of the ground they are buried in - if it is dry then very fine sand is better than loam ,as this tends to have air pockets. If it is wet the reverse is true.
. In free air the tables suggest 728A for 4 core 3 phase 400mm2 cable and clipped direct 673A both suggest that a pair should run warm but , not as much as 100C, unless the ambient is high, so how tightly are they grouped, and how much airflow is there around the hot spots.
The buried rating will depend on the make up of the ground they are buried in - if it is dry then very fine sand is better than loam ,as this tends to have air pockets. If it is wet the reverse is true.
. In free air the tables suggest 728A for 4 core 3 phase 400mm2 cable and clipped direct 673A both suggest that a pair should run warm but , not as much as 100C, unless the ambient is high, so how tightly are they grouped, and how much airflow is there around the hot spots.
