Thermoplastics become softer and more malleable when exposed to heat, whereas thermosets maintain their shape better under similar conditions. This thermal behavior makes each type suitable for specific applications.

Electrical currents flowing through conductors generate heat depending on resistance and current strength. As such, thermoset-insulated cables offer advantages over thermoplastic ones when it comes to handling higher current loads or operating in hotter environments without sacrificing cable performance, since their structural integrity remains intact under these conditions.

Ensuring that the cross-linking process is properly completed during the production of thermoset-insulated cables is crucial to achieving the desired properties. Conducting this test verifies whether the cable insulation meets the necessary standards.

Before beginning the test, the plastic covering the metal conductor is removed, and a tubular or dumbbell-shaped sample is prepared based on the conductor's dimensions.

The test involves placing the samples in an oven at high temperatures (as per the cable standard requirements), suspending them from a holder with a weight attached to their lower end. The weight used depends on the sample's cross-sectional area and is determined by the relevant testing standard.

After the predetermined time has elapsed, the cable's elongation is measured while hot and compared to its original length. Once the weight is removed, the sample is allowed to cool to room temperature to measure the permanent elongation value.

If both the hot elongation and permanent elongation values meet the required limits, the cross-linking level is considered adequate.