The best tool for crimping ferrule sleeves is a ferrule crimper. But when you don’t have the special tool at hand and you want to terminate a stripped electrical wire, you can use pliers. However, note that you might not get the same integrity and strength with the pliers as you would with a ferrule crimping tool. But the outcome is better than inserting bare wire directly into the connector, nonetheless.
What is a wire ferrule?
A wire ferrule is a type of metal sleeve (mainly tin-plated copper) for capping the end of a stranded electrical wire to prevent the wire strands from fraying or separating. Once crimped or swaged, the ferrule tube binds the fine electrical wire strands together to make one solid core. This ensures that no wire strand is left out when connecting the wire end to the connector.
Therefore, wire ferrules are good for making reliable electrical connections. They ensure maximum electrical contact of your electrical wires with screw-type terminals and breakers.
Ferrules vs standard crimp connectors
Wire ferrules and wire crimp connectors do more or less the same work of terminating electrical wire. They mainly on how the crimping takes place. For ferrules, you crimp the metal tubing itself whereas for the crimp connectors you crimp the part with insulation.
Another difference is that a ferrule tube acts as a cap for wrapping the stripped wire whereas the standard pin terminal acts as a metal extension of the wire end. An example of a standard crimp connector is the terminal lug you find on battery posts or the grounding wire connecting to the chassis on most appliances.
How do you crimp ferrules?
As I mentioned, the best way to crimp ferrule connectors is by using a ferrule crimping tool. This special crimping tool compresses the ferrule tube over the wire strands to keep them intact and to eliminate any wiggle that may affect the integrity of the electrical connection.
However, when you do not have ferrule crimping pliers at hand, you can try to use regular wire crimpers or any pliers with a crimping feature. However, the results with these alternative tools are not the same as using a proper ferrule crimper tool. They do not create a proper cold weld as does a ferrule crimper.
Crimping wire ferrule with ferrule crimping pliers
Follow these simple steps crimp a ferrule cap with a ferrule crimping tool,
Step 1: Identify the size of wire you want to crimp.
Step 2: Select the right size ferrule connector. The size of the wire you want to terminate will guide you. Moreover, since most wire ferrules are color-coded, you can use the ferrule color code chart below to quickly identify the right ferrule size for your electrical wire.
Step 3: Strip the wire to the proper length. It should be long enough to fit in the ferrule tube (about 1 cm). To avoid making mistakes, just measure the length of the ferrule tube and strip away the same length of wire insulation.
Step 4: Insert the stripped wire end into the ferrule terminal. The bell-type entry of the ferrule will guide the stranded wire nicely all the way to the insulation so that no conductor is visible.
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 5: 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 6: Do a pull test on the wire to make sure it is tightly crimped. Try to pull the crimped ferrule off from the wire. If it comes off or if you notice any wiggling, repeat the last two steps. Otherwise, your wire is properly crimped and ready to make a quality electrical connection.
Crimping wire ferrules with pliers
Option 1: Using regular wire crimper
When you don’t have a ferrule crimping tool and you need to connect a ferrule terminal onto a flex electrical wire, you can do it temporarily with regular wire crimping pliers. Ideally, the regular wire crimpers are for crimping terminal connectors. Therefore, they are not the most suitable for crimping ferrules and will most likely make a poor crimp. However, they are good in emergency situations nonetheless.
A poor crimp leaves air spaces between the connector and wire. These air spaces can collect atmospheric moisture which may corrode both the wire and connector. Ultimately, the corrosion of a wire terminal results in a poor electrical connection. That is why I only recommend this method as a temporary solution for crimping wire ferrules.
Step 1: Identify and prepare the wire you want to terminate.
Start by identifying the wire gauge so that you can pick the right ferrule connector. Then strip away the insulation on the end of the wire. About 1 cm.
Step 2: Select the ferrule connector and fit it over the stripped wire end. Ensure all the strands of the flexible wire fit inside the ferrule tube. Also, ensure that the stripped wire goes all the way into the metal tube such that the insulation on the wire only touches the top of the tube.
Step 3: Crimp the ferrule terminal assembly. Place the ferrule assembly between the jaws of the wire crimper and start crimping from the end where the insulation on the wire starts. Crimp all the way to the other end of the metal tube leaving small gaps between the crimps.
Step 4: Do a pull test to ensure that the wire is tightly held in place by the crimped ferrule.
Option 2: Using pliers with a crimping function
Some regular pliers such as the Milwaukee 7-in-1 combination pliers have a wire crimping feature. However, the crimper is for ordinary pin connectors, not ferrule caps. Therefore, you will follow the procedure for Option 1 above to crimp ferrule with these types of pliers.
Although crimping ferrules with ordinary pliers or crimpers is not the best way to crimp them, it helps to eliminate the problems associated with connecting the bare stranded wire to screw terminals.
Some of those problems include the shorting out of equipment by stray wire strands and insufficient surface area for electrical contact. Also, connecting stranded wire on a screw terminal without a ferrule eventually results in a mechanically and electrically weak connection.
If you have worked on electrical industrial panels, I bet you know how much damage a stray wire strand can cause. That is why you should always terminate flexible electrical wires with ferrules or terminal connectors before screwing them on the terminal block.