In general, the performance of the insulation materials depends on the temperature of the materials in operation. The higher the operating temperature, the higher the chance of chemical deterioration, which shortens the life of the insulation material. If there is a need for long term use, it is necessary to keep the operating temperature at the lowest values. Therefore, if a safe operation is expected on the expected service life of the insulation, it is important to determine the temperature limits to achieve this.

Factors that affect the resistance of a conductor include temperature. The resistance of a conductor may rise or fall depending on the temperature. The temperature-dependent change of conductive substances takes place according to a certain coefficient.

Insulation materials are used in order to prevent the conductor wires from contacting each other, to prevent short circuits and to protect the cables from external factors. The insulation properties also vary depending on the type of material used for the insulation. It is critical to insulate the cables to ensure the safety of the system and the safety of people. Different insulation materials are used depending on where the cable will be used.

Factors that break the strength of insulation include temperature. Variable temperature conditions can cause cable hardening, breakage, and reduced cable service life.

Electrical testing by authorized laboratories includes insulation resistance testing at maximum conductive operating temperature.

When conducting the insulation resistance test at ambient temperature, the cable whose vessels are removed from the ends is kept in the water at ambient temperature for one hour. Then, a direct current between 80 and 500 volts is applied to the cable for a maximum of five minutes until a stable result is obtained. The same method is applied for the insulation resistance at the maximum conductor operating temperature, but the only difference is that the maximum conductor operating temperature of the cable is immersed in water within a range of plus minus two degrees.