Due to which of the following reasons the cables should not be operated too hot ?
A. The oil may loose its viscosity and it may start drawing off from higher levels
B. Expansion of the oil may cause the sheath to burst
C. Unequal expansion may create voids in the insulation which will lead to ionization
D. The thermal instability may rise due to the rapid increase of dielectric losses with temperature
E. All of the above