I'm working in a project where I have a tunnel of 3-meter height and 3.7-meter width. In this tunnel there are around 37(single core) medium voltage cables laid on cable trays staked on both sides as illustraed in the attached image. The separation dsitance as shown between each tray is 350mm and every cable is sperated from the adjacent other cable by more than double the diameter of the single core cable as also shown within the same tray. The question is how to figure out the derating factor for such arrangement, taking into consideration that the IEC 60502 table B.23 considers maximum of 3 horizontal cable trays above each other ?
Thanks in advance for your help..