Wire Ferrules

Wire connectors (ferrules) are used to facilitate wire insertion into a terminal clamp. They ensure reliable electrical connections and prevent the unraveling of stranded wire. Ferrules are sized according to the conductor size and the barrel length. The conductor size is the cross-section of the wire it will be connected to and the barrel length indicates the stripping length of the wire. Ferrules are available in insulated and uninsulated designs. Insulated ferrules have a sleeve made of polyamide or PVC that covers part of the tin-plated copper tube. The sleeves are color-coded according to the wires size the ferrule is connected to. Uninsulated ferrules do not come with a plastic sleeve. The shorter length and uninsulated body makes them a better choice for printed circuit board terminal blocks and other terminal blocks with smaller clamps and narrow widths.

When installing a ferrule, the wire should be cut as squarely and evenly as possible. The stripped length of the wire will depend on the barrel length of the ferrule. The wire insulation should be stripped to a length that allows the conductor end to reach the tip of the ferrule when inserted. Many wire strippers have a device that allows the user to set the strip length. After the insulation is stripped, the strands of the conductor should be twisted to ensure that there are no stray strands. The wire can then be inserted in the ferrule so that the insulation edge is fully covered by the plastic collar (when using an insulated ferrule). Finally, the wire and ferrule are crimped using an appropriately sized ratcheted crimper.