Plasticizers are substances which give polymers the firm shape. When plasticizers are damaged, the cable insulation softens. This exposes the conductors and results in a short circuit or a ground fault.
Oil is a substance which is widely present in the industrial
environment. Even if the cables do not come in direct contact with the oil, oil droplets which drift in the air can settle on the surfaces of the cable insulation and can initiate the degradation process.
Hence, it is essential to ensure that the cables used in industrial environments are resistant to oil.
Cables are classified on the basis of their resistance to oil as UL62, UL Res 1, Ul Res 2, UL AWM 21098