How to Crimp Ferrule? STEP 1 Identify the size of wire you want to crimp. The size of the wire will help determine what size of ferrule you need. Typically, a ferrule should be the same size as the wire. STEP 2 Insert the stripped wire end into the ferrule terminal. Make sure the tip of the wire touches the bottom of the tube. If the stripped section is shorter, remove more insulation from the wire with a wire stripper. If the section is longer, cut it to length with a pair of diagonal pliers or ordinary wire cutters. STEP 3 Crimp the ferrule assembly with your crimping tool. Simply insert the ferrule terminal assembly inside the jaw of the crimping tool and squeeze the handles firmly to crimp. Squeeze them all the way to tightly secure the wire into the ferrule connector. STEP 4 Test the quality of the crimp. Do a pull or tug test on the crimp to make sure it is tight and will not come off. Pull the crimped part and the rest of the wire in opposite directions.