Test procedures are generally in accordance with an internationally recognized standard procedure like the one mentioned in ASTM D638-14 so that results are consistent between labs. But all standards like ASTM E8 (metals) and D638 (plastics) more or less follow the following steps:
Step 1 : Note the cable insulation specimen dimensions including length, thickness and cross sectional area.
Step 2: Insert a sample of a material between two fixtures or grips.
Step3: Select speed and load parameters in accordance to the standard
Step 4: Apply force to the material through the use of a universal test machine (UTM) or force testing machine.
Step 5: Increase the force while measuring the change in length of the sample.