Crimp terminal connectors, what are they?

You can't avoid crimp connectors if your job involves any form of wiring. Read this article to learn more about terminal connectors and why you need them for your electrical project.

When terminating stranded wires to terminals or splicing wires together, you should find a good way to manage the stripped wire ends. This ensures that you get a good and safe electrical connection every time.

Managing stripped wire ends is extremely important when dealing with stranded electrical wires. It keeps the wire strands together to prevent them from getting to the wrong places. Just so you know, loose electrical wire strands are some of the leading causes of electrical shocks and fires.

How to deal with stranded wire ends

Stranded wires are flexible and easy to manipulate in tight spaces. But they can be a menace if you don’t manage the loose wire strands properly after stripping away the insulation.

There are many ways to manage loose wire ends after stripping off the insulation. You can solder the wire strands together, use crimp terminals, or use bootlace wire ferrules. Each of these methods requires a specific tool and tactic.

For crimp terminals, you need a crimping tool. It can be a pair of crimping pliers, hydraulic crimpers, or hammer-style crimper. In heavy-duty industrial applications, you may use a 3-point crimper with a ratchet or impact driver to crimp very large wires.

To install wire ferrules, you need a wire ferrule crimper. Again, you can use a handheld or hydraulic ferrule crimper. And for soldering, you need a soldering gun and solder wire.

Soldering and crimping are quite different. They create different types of electrical bonds. Soldering uses heat to create a hot weld joint whilst crimping uses compression to create a cold weld joint.

In this article, I focus on crimp connectors. I explore the different types of crimp connectors and their uses, how to install crimp connectors, and the various crimping tools you can use.

What is electrical wire crimping?

Electrical wire crimping is simply the process of compressing a terminal connector around a wire using mechanical compression. The compression deforms the connector, causing it to bind mechanically with the wire. This produces a solid cold weld joint.

Crimping wire is an effective way to join or terminate stranded electrical wires.

crimping a connector
Crimping a connector

Types of terminal connectors

There are two major types of terminal connectors; bootlace ferrules or regular crimp connectors.

Bootlace ferrules are basically tin-plated copper tubes. They give your stranded wire-end a solid-wire property. These connectors are useful when terminating flex wire to a screw terminal.

In contrast, regular crimp connectors do more than hold loose wire strands together. They provide various configurations that allow you to terminate wire to different types of electrical terminals. You can even use the connectors to splice wires. Some of the common types of crimp terminals are blade type, ring type, and many others I have mentioned in the next section.

What are regular crimp connectors?

As I’ve mentioned, crimp connectors are special types of wire terminals for managing wire ends. You can use crimp connectors to terminate wires or join multiple wires together. They give your wire-end a specific configuration. For example, you can use fork terminals when you need a forked end for connecting to screw terminals. Alternatively, you could use a stackable terminal if you want to easily splice wires.

common types of crimp connectors
Common types of crimp connectors

Crimp connectors give electrical wires a lot of versatility. They help to create reliable and secure electrical connections.

Crimp connectors are generally intended for use with stranded wire. Unless a crimp is listed for use with solid wire, a crimped connection on a solid wire is bound to fail.

Crimp connector types

There are many types of crimp connectors. They come in different shapes depending on their applications. The most common types are:

  • Spade connectors or disconnect crimp terminal
  • Bullet crimp terminals
  • Butt connectors or splice connectors
  • Fork crimp terminals
  • Ring crimp terminals
  • Piggyback crimp terminals or stackable terminal
  • Pin terminal connectors

Crimp terminals are either insulated or non-insulated. Insulated crimps have a color-coded insulation cover over the metal barrel while non-insulated are bare metal.

Some insulated crimps have heat shrink tubing instead. They are suitable for use where water can be a problem. Once you crimp them, you use a heat gun to shrink the tubing to create a waterproof seal.

Most crimp connectors come in pairs of male and female. Male crimps have a prong end and female crimps have a socket-like end.

To use them correctly, you should mate the male terminal with its corresponding female connector.

Crimp connector sizes

Crimp connectors come in a variety of sizes. Each size accepts a range of wire gauges. The three most common crimp terminal sizes are 18 – 22 AWG, 16 – 14 AWG, and 12 -10 AWG. The size is printed on the connector. Furthermore, insulated crimps are color-coded red, blue, or yellow, respectively.

How to select the right size crimp connector

It may seem difficult to tell what size of crimp connector you need for your project. But the cardinal rule is that the wire size must be within the size range of the crimp connector. This means that a 12 -10 AWG (yellow) crimp terminal can accept 12 and 10 AWG wire. It is that simple!

Some sizes tend to overlap. And this leaves the selection of the appropriate crimp connector to your judgment. For instance, you can use a 12 – 10 AWG crimp terminal on 14 AWG wire if it is all you’ve got. Similarly, it is ok to use a blue crimp connector on 18 AWG wire. Simply put, you can go one wire size down of the lowest crimp range and you will be safe.

How to attach crimp connectors to wire

Crimping regular terminal connectors to electrical wire is quite straightforward. You just need the right size of crimp terminal, the right tool, and to follow these simple steps.

I am assuming that you have already stripped the wire to the correct length. If you have not, here is how to do it: how to strip wire with wire strippers.

Steps

Step 1: Pick the crimping tool of choice

You can use a hydraulic crimper or regular crimper pliers. I prefer to use regular crimping pliers because they are fairly affordable and more versatile for big and small projects.

Step 2: Pick the right size crimp connector

Remember the cardinal rule when selecting an electrical wire crimp connector. The size of the wire must be within the size range of the crimp connector. Follow that and you will be safe.

Step 3: Select the correct crimping jaw

You can use the color guide or wire-size range marking on the crimping tool to know which jaw to use to crimp your connector. If your crimping tool is color-coded, you will see a red, yellow, or blue dot against each crimping jaw. Place the insulated terminal on the jaw whose color coding matches the color of the connector.

If you are using a non-insulated connector, use the size range specification on the jaws. Place the terminal connector on the jaw that matches its size range.

Step 4: Insert the wire into the crimp connector

Gently squeeze the jaw to hold the terminal in place whilst you insert the stripped wire. Put the wire through until the insulation on it touches the top of the metal barrel. Also, ensure only a tiny bit of the conductor brush is sticking out at the end of the barrel. Resize the stripped core if you have to until you get it right.

Some people advise that you twist the wire strands a little bit to make it easy to get them all into the crimp connector. I don’t recommend it because you might contaminate the freshly stripped copper wires and accelerate corrosion. Twisting can also increase the cross-sectional area of the wire and make it even harder to insert into the connector.

The easy way around this is to strip the wire when crimping. Also, make sure the core strip length is correct to avoid resizing again, which could fray the wires.

Step 5: Squeeze the crimper jaws

Position the crimp connector and wire assembly properly on the jaw. Squeeze the handles of your crimping pliers all the way to make a good crimp. One good crimp is good enough. But, you can make a second crimp if there is space on the barrel.

Step 6: Do a pull test

Lastly, do a tug test on the new crimp to test the integrity of the bond. Simply pull the connector and wire apart to see if they come apart. Don’t pull so hard.

If the connector does not come off, then the crimped connection is nice and firm. Now you can be sure that the electrical connection will be safe and reliable.

Why should you crimp wires with regular crimp connectors?

Some people use crimp connectors on electrical wires because it is a norm or because they make electrical projects look neat. While these are valid reasons, there are three main reasons why you should always crimp electrical wires with crimp connectors.

Reason 1: Crimp connectors can connect to different types of terminals

Unlike wire ferrule crimpers which are only useful for terminating wire to screw terminals, regular crimp connectors provide more configurations. These different configurations make crimp terminals more versatile and reliable for use in different situations.

For instance, spade terminals are indispensable in auto wiring. The female spade terminals are used to terminate auto wires to auto connectors. Ring connectors are a defacto in connecting ground wires to the chassis.

Terminal connectors with heat shrink are for when you want a waterproof seal electrical connection. They are good for boat wiring and other marine applications. Butt connectors with heat shrinks are also common in RV wiring and any other application where water can be an issue.

Pin-type connectors function as bootlace ferrules. They are good for terminating wires to narrow terminal connectors. You can use them in your power electronics project to terminate sensors wires to small terminal blocks.

In short, crimp connectors are the most versatile type of crimps.

Reason 2: Male and female crimp connectors are easy to connect and disconnect

Male and female crimp connectors make splicing wire an easy task. You can easily connect and disconnect the two mating connectors. Some splice connectors such as the piggyback terminal connectors make joining more than two wires a snap.

Reason 3: Crimp terminals increase the odds of a good connection

A good electrical connection is guaranteed as long as you use a good quality crimp connector and you crimp it properly.

You can tell a crimp terminal is good if it crimps well, passes the tug test, and is plated to prevent corrosion.

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