How to Crimp a Wire Properly for Long-Lasting Electrical Connections

A quality ratcheting wire crimper tool in action, creating a solid crimp on an insulated connector. Proper use of a crimping tool forms a gas-tight bond between the wire and connector for maximum reliability

Crimping wires is a fundamental skill for electricians, DIYers, and hobbyists. Whether you're wiring automotive electrical connectors, doing home wiring, or working on electronics, using a crimping tool (also known as a wire crimper, crimper tool, or crimping pliers) is often the best way to join a wire to a terminal or splice. A proper crimp creates what is essentially a cold weld – compressing the connector and wire together so tightly that the metals fuse into one mechanically and electrically secure connection. This results in a gas-tight junction that keeps out oxygen and moisture, preventing corrosion and ensuring low resistance over time. In fact, a well-executed crimp can be as strong as a soldered joint but with greater resilience against vibration. In this guide, we'll show you how to crimp a wire step by step for long-lasting connections, discuss different types of crimpers and connectors (from standard insulated terminals to ferrule crimpers and heavy-duty lug crimpers), and share pro tips to help you avoid common mistakes. By the end, you'll understand why professional electricians and mechanics rely on crimping tools for durable electrical connections – and how to achieve perfect crimps yourself.

Tools & Materials Needed

Before starting, gather the proper tools and materials. Using the right equipment is crucial for a successful crimp. Here's what you'll need:

• Stranded Wire: Only use stranded wire for crimp connectors. (Solid wire is not recommended for crimping, as it doesn’t deform and hold as well. In fact, industry standards like NASA explicitly prohibit crimping solid wire.) Ensure you have the correct gauge wire for your application.

• Wire Connectors: Choose quality crimp connectors sized for your wire gauge. Common types include butt splices, ring terminals, fork (spade) terminals, and bullet connectors. For example, butt splice connectors are used to join two wire ends, while ring terminals allow bolting a wire to a stud. These connectors come insulated (vinyl/nylon or heat-shrink insulation) or non-insulated. Pro tip: use connectors with tin-plating to resist corrosion and, for insulated terminals, choose high-quality ones that have a metal sleeve inside to grip the wire insulation (cheaper connectors lack this, making them less reliable). Also pay attention to connector size coding:

  • Red insulated connectors: for 22–16 AWG wires (smallest).

  • Blue insulated connectors: for 16–14 AWG wires (medium).

  • Yellow insulated connectors: for 12–10 AWG wires (largest common size).
    (These color codes are widely used in the U.S. for insulated crimp terminals.)

• Wire Stripper: A dedicated wire stripping tool is essential to remove insulation without nicking the wire strands. Many electricians prefer a precision stripping tool or one with gauge-specific holes for clean results.

• Cable Cutter: If you need to cut wires to length or trim off damaged ends, use a proper cable cutter. This ensures a clean cut without crushing the wire. Clean, even wire ends insert into connectors more easily and crimp better.

• Crimping Tool (Wire Crimper): This is the star of the show. A quality crimping tool applies the even pressure needed to crimp connectors onto wires. Ratcheting crimpers are highly recommended for most electrical connectors, as they apply consistent pressure and won’t release until a full crimp is achieved. A ratchet crimper tool also usually has multiple die sizes for different connector types or gauges. Ensure your crimp tool supports the connector type and wire gauge you're using. For example, the Haisstronica Ratchet Wire Terminal Crimping Tool (AWG 22–10) is designed for common insulated and heat-shrink connectors in the 22 to 10 AWG range – a versatile choice for most DIY and automotive projects (see our internal link below). If you’re using specialized connectors like open barrel terminals, ignition terminals, or ferrules, you may need a specialty crimping tool (more on that later).
  Internal link: For an all-in-one solution, check out the Haisstronica Ratchet Wire Terminal Crimping Tool for AWG 22–10 Heat Shrink Connectors – a durable ratcheting crimper that ensures a tight, uniform crimp every time.

• Heat Shrink Tubing or Heat-Shrink Connectors (optional): If using non-insulated terminals or wanting extra protection, have appropriately sized heat shrink tubing to cover the crimped connection. Many connectors come with insulation, but for waterproof or marine applications, heat-shrink connectors (with adhesive lining) are ideal for a long-lasting seal.

• Heat Gun or Lighter (optional): To shrink tubing or heat-shrink connectors after crimping.

• Multimeter or Continuity Tester (optional): Useful for testing the finished connection’s continuity and quality.

• Safety Gear: It’s a good practice to wear safety glasses when crimping and cutting wires. Also, ensure power is off on any circuits while you work.

Having these tools and materials ready will make the crimping process smooth and ensure you create a reliable connection.

Step-by-Step: How to Crimp a Wire Effectively

Let's walk through the process of crimping a standard insulated wire connector (for example, attaching a ring terminal or butt splice to a wire). The same general steps apply to most wire crimping jobs. Be sure to match your connector type and size to the wire gauge, and use the appropriate die on your crimping tool.

1. Prepare the Wire: Start by cutting your wire to the needed length using cable cutters. Next, strip off a portion of insulation from the end of the wire using a wire stripper. Strip about 1/4 inch to 1/3 inch (6–8 mm) of insulation (or as specified by the connector manufacturer) – just enough so that the bare wire will fill the metal barrel of the connector. Be careful not to nick or cut any of the wire strands. Nicked strands can weaken the connection or cause the wire to break later. After stripping, if the wire is stranded, twist the strands gently between your fingers so they form a tight bundle. This makes insertion easier and ensures all strands are captured by the crimp. (Reminder: use stranded wire, not solid, for crimp connectors for best results.)

2. Select the Correct Connector: Choose a crimp connector that matches your wire gauge and application. For example, if joining two wires end-to-end, use a butt connector; if adding a wire to a stud or screw terminal, use a ring or fork terminal. Verify the connector’s gauge rating (usually printed on the packaging or the connector itself for non-insulated terminals). If using insulated connectors, the color (red, blue, yellow) should correspond to the wire gauge as noted earlier. Never force a wire into an undersized connector or use an oversize connector that fits loosely – either mistake can lead to a weak crimp. The wire should slide into the connector’s barrel easily but with minimal extra space. If you are using a heat-shrink connector, ensure the heat-shrink tubing (if pre-attached) is slid back on the wire away from the crimping area for now.

3. Insert the Wire into the Connector: Fully insert the stripped end of the wire into the connector barrel. For a butt splice, insert until the stripped wire end is roughly centered in the splice (or until it butts up against the wire from the other side if splicing two wires). For a ring or spade terminal, insert until the insulation of the wire just meets the metal barrel and the copper strands are all inside. Ideally, a tiny bit of the wire’s stripped end may be visible on the other side of the barrel’s inspection window or end – this indicates the wire is fully seated. No bare wire should be exposed outside the connector, except perhaps a small hint at the tip. Also make sure no stray strands are sticking out; all strands must be inside the barrel. If even one or two strands miss the barrel, remove the wire, re-twist, and insert again, because those loose strands could reduce conductivity or create a short.

4. Position the Connector in the Crimper: Open your crimping tool jaws and place the connector (with wire inserted) into the appropriate die slot. Most hand crimpers have multiple notches/dies for different connector sizes or types. For insulated terminals, many crimpers have color-coded labels on the dies (match red connector to red die, blue to blue, yellow to yellow). For non-insulated, use the die marked for the corresponding wire gauge. Align the connector so that the crimp tool’s indent (the “tooth”) will press into the proper area of the connector barrel. Tip: If your connector has a seam, position it so the crimping tool’s indent will press on the side opposite the seam (this helps prevent the seam from opening up). Hold the connector in place in the die, and ensure the wire hasn’t slipped out during this positioning.

5. Crimp the Connector: Squeeze the crimp tool handles firmly and steadily. If using a ratcheting crimper, the tool will ratchet tighter as you squeeze; press the handles until the ratchet cycle completes and releases automatically. This ensures full compression. If using a non-ratchet crimper, apply heavy pressure—crimp with both hands if necessary—to deform the connector fully onto the wire. The goal is to plastically deform the connector barrel around the wire strands, creating a tight bond. Once the crimp is made, release and remove the connector from the tool.

6. Inspect the Crimp: This step is critical for quality control. Visually inspect that the connector’s barrel has been crushed uniformly and that the wire’s insulation is very close to the barrel (for insulated terminals, the insulation of the wire often goes slightly into the connector’s plastic sleeve). You should see an imprint or indentation where the crimp tool compressed the connector. Check that the wire is securely attached: give the wire a moderate tug – it should not pull out of the connector if the crimp is good. If it slips out or feels loose, the crimp is insufficient (in such a case, do not crimp again on the same connector; cut it off and start over with a new connector). Also verify that the barrel isn’t cracked and that any insulation on the connector isn’t damaged.

7. Heat Shrink (if applicable): If you used a heat-shrink style connector or added separate heat-shrink tubing, now is the time to seal the connection. Slide any tubing into place (centering it over the joint) and apply heat with a heat gun or lighter. Heat evenly until the tubing shrinks and adhesive (if it’s lined heat shrink) melts, creating a tight seal over the connection. The tubing should snug down onto the wire and connector, with no gaps or bubbles. This provides excellent insulation and strain relief, and if adhesive-lined, a waterproof seal.

8. Test the Connection: For critical connections, it’s wise to test the crimped wire. Use a multimeter to perform a continuity test – you should have near-zero resistance through the connection. Wiggle the wire a bit while testing to ensure it’s stable. If the circuit will carry significant current, you might also do a voltage drop test under load to ensure the crimp is not high-resistance. In automotive or vibration-prone environments, it’s good practice to give the wire a more forceful tug and bend to simulate stress – a proper crimp will hold firm.

By following these steps carefully, you’ll crimp wires like a pro. Next, we’ll discuss some common mistakes to avoid and additional tips to ensure your electrical crimps are rock-solid.

Common Mistakes to Avoid

Even with the right tools and steps, there are a few pitfalls to watch out for. Avoid these common mistakes when crimping wires:

• Using the Wrong Size Connector: If the connector barrel is too large for the wire, the crimp won’t compress tightly and the wire can slip out. Too small, and you won’t be able to insert the wire fully (or you’ll end up severing wire strands). Always match the connector’s AWG rating to the wire’s gauge. Also, use the correct section of the crimping tool’s die for that connector size. A mismatch can result in a weak crimp that may fail under tension or electrical load.

• Crimping on the Insulation (or Not on the Wire): Ensure that the crimp tool’s jaw is positioned over the metal barrel that holds the stripped wire, not on the wire’s insulation. Crimping down onto insulation instead of bare wire will result in little to no electrical contact. Many insulated terminals are designed to grip the insulation as a form of strain relief separately from the conductor crimp – but this is usually done with a second crimp or a different section of the connector. The primary crimp must be on the conductor. Double-check placement before you squeeze the tool.

• Not Stripping Properly: Leaving too much insulation (so that not enough bare wire enters the connector) or stripping too much (leaving bare wire exposed beyond the connector) are both problematic. Strip the correct length so that the wire’s insulation butts up against the connector’s metal barrel. If too much bare wire is exposed, it could cause a short or corrosion. If too little is exposed, the crimp will grab the insulation instead of the copper strands.

• Inadequate Crimp Pressure / Incomplete Crimp: One big advantage of ratcheting crimpers is that they force you to complete the crimp fully. With non-ratcheting tools (or improvising with pliers – not recommended), it’s easy to under-crimp (stop squeezing too early) resulting in a loose connection. Always crimp until the tool completes the cycle or you’ve applied the maximum needed force. The finished crimp should show a clear imprint from the dies and should firmly capture the wire. If you can rotate or easily move the connector on the wire by hand, the crimp is too loose.

• Using the Wrong Tool: Don’t try to use pliers, vice grips, or a random crimp tool not meant for your connector type. While it might squash the connector, it often won’t apply the correct shape or force. This leads to unreliable connections that can slip or have high resistance. Each connector style (insulated terminal, open-barrel terminal, coax connector, etc.) has a corresponding crimp tool design for a reason. Use a proper wire crimping tool sized for your connector. Also, avoid old or worn-out crimpers that no longer close fully or evenly.

• Crimping Soldered or Solid Wires: As mentioned earlier, do not tin (solder) the wire strands before crimping, and avoid crimping solid wire. Soldered wire is actually worse for crimping because the solder makes the wire stiff and prone to cold-flow under pressure, resulting in a loose connection over time. In fact, authoritative guidelines state that crimping solder-tinned wire is not allowed. Likewise, solid wire doesn’t deform as well as stranded, leading to poor retention. Stick to bare stranded wire for all crimp connectors – it will “cold form” into the crimp and hold much better.

• Reusing Connectors: Crimp connectors are generally single-use. Once a connector has been crimped onto a wire, it is deformed permanently and should not be reused or re-crimped onto a new wire. Reusing a crimped connector can lead to a very unreliable connection (and often you’ll find it’s impossible to remove the old wire without damaging the connector anyway). If you mess up a crimp or need to change something, cut it off and use a fresh connector. They’re cheap insurance for a good connection. (In a similar vein, do not attempt to “re-crimp” a connection that tested poorly – start over with a new connector.)

• Cheap or Low-Quality Materials: All connectors and tools are not created equal. Skimping on very cheap crimp connectors can result in brittle metal or poor plating that corrodes quickly. Similarly, a flimsy crimping plier without a ratchet may not apply consistent pressure. Invest in decent-quality connectors (preferably tin-plated copper for most electrical work) and a good crimping tool. Your connections will thank you by lasting years or decades. Using known brand connectors and tools helps ensure the crimp specs (die sizes, etc.) match up correctly. If you have connectors from a kit, consider using the matching ratcheting crimper tool that the manufacturer recommends or provides.

By steering clear of these mistakes, you’ll dramatically reduce the chance of a bad crimp. Next, we’ll cover some pro tips and techniques that can further improve the durability of your wire crimps.

Pro Tips for a Perfect Crimp

Even seasoned electricians have a few tricks to ensure every crimped connection is top-notch. Here are some pro tips to elevate your crimping game:

• Use a Ratcheting Crimper for Consistency: As mentioned, a ratchet crimping tool is highly recommended for most jobs. It ensures you apply the right amount of force every time (and won’t let go until the crimp is properly compressed). This takes the guesswork out of crimping. If you’re doing multiple connections, a ratcheting wire crimper tool will give you more uniform results and reduce hand fatigue compared to squeezing non-ratchet pliers with full force each time.

• Dielectric Grease for Automotive/Marine: When making electrical connections in automotive, marine, or outdoor equipment, consider applying a small dab of dielectric grease to the wire and connector before crimping (or directly into the connector barrel). This silicone-based grease is non-conductive but helps prevent moisture intrusion and corrosion inside the crimp. Some professionals also put a bit on before sealing a heat-shrink connector. (Do note, however, that if you are using heat-shrink with adhesive liner, additional grease is usually not necessary.)

• Double Crimp on Long Barrels: If you’re using long barrel lugs or splice connectors (common with heavy gauge lugs), you might perform two crimps: one at each end of the barrel, to ensure the entire connection is secure. Some long barrels are even marked for multiple crimps. Follow the connector’s guidelines.

• Label or Color-Code Wiring: This isn’t about the crimp quality per se, but for long-term maintenance it’s wise to label your wires or use colored connectors (or boots) to indicate certain functions (e.g., red for positive, black for negative in DC systems). Many crimp connectors come color-coded for size, but you can also use that color coding to your advantage in organization. It makes troubleshooting easier down the line.

• Practice on a Scrap Wire: If you’re new to crimping or using a new tool/connector type for the first time, do a test crimp or two on scrap wire and connectors. Then inspect your work by maybe cutting the crimped connection in half to see the cross-section. You’ll quickly see if you’re achieving full compression and learn how the proper crimp looks internally. This sacrificial test can save your actual project from a bad connection.

• Tug Test Every Crimp: Develop the habit of performing a quick “tug test” on each crimped connection right after crimping (as we described in the steps). It’s better to have a connector pull off now, when you can redo it, than later when the assembly is in use. A solid crimp should handle a reasonable pull equivalent to the wire’s own tensile strength without coming off. If it passes this test, it’s unlikely to fail in normal service.

• Use Heat Shrink for Added Strain Relief: Even if your connectors are insulated, adding an extra layer of heat-shrink tubing over the junction of the wire and connector can provide additional strain relief and insulation. This is especially useful for connections that will experience movement, vibration, or exposure to the elements. Overlapping the tubing so it covers both the connector and a bit of the wire insulation on each side creates a nice transition that supports the wire.

• Right Tool for the Connector: Keep in mind that specialized connectors (which we’ll discuss next) often require their own specialty crimpers. Don’t try to force them in a generic crimp tool. For example, ignition plug terminals, coax connectors, and MC4 solar connectors each need a specific crimp profile. If you frequently do a certain type of crimp (open-barrel pins, for instance), it’s worth getting the proper tool or at least a die set that fits your ratcheting crimper frame.

• Periodic Tool Calibration: For heavy users, note that crimp tools, especially ratcheting ones, can sometimes go out of calibration or the dies can wear. Higher-end tools might have calibration settings or replacement dies. If you notice your crimps aren’t as tight as they used to be, inspect your tool. It may need adjustment or replacement after long-term use. Keeping the tool clean and occasionally lightly oiling the hinge can also prolong its life and ensure smooth operation.

Implementing these tips will help ensure your wire crimps are consistently excellent. However, different wiring tasks may call for different types of connectors and tools. In the next section, we’ll explore various types of crimp connectors – such as ferrules, spark plug terminals, and heavy-duty lugs – and how to handle them.

Crimping Different Types of Wire Connectors

Not all wire connectors are the same. Beyond the common insulated ring and butt connectors, you may encounter specialized terminals that require different techniques or tools. Let’s look at a few special categories and how to crimp them properly. This will also introduce some secondary keywords (like ferrule crimping, spark plug wire crimper, etc.) relevant to those specific tasks.

Crimping Wire Ferrules (Ferrule Crimpers)

Wire ferrules are soft metal sleeves (usually tin-plated copper) used to terminate the ends of stranded wires, typically when connecting to screw terminals (as in circuit breakers, relays, or European-style terminal blocks). Crimping a ferrule onto a wire keeps all the strands bundled neatly and prevents fraying or breakage under the screw, providing a reliable connection.

Tools: Ferrules are crimped using a ferrule crimper – a special type of crimping tool that often makes a square or hexagonal crimp. These are almost always ratcheting tools, and many are self-adjusting to accommodate a range of ferrule sizes (for example, crimping 28 AWG up to 8 AWG ferrules with one tool by automatically sizing the crimp). If you work on control panels or audio equipment with screw terminals, a ferrule crimping tool is invaluable. Ensure you have the right size ferrule for your wire (they come in color-coded insulation collars in metric sizes, but many kits provide an AWG-equivalent chart).

Technique: Strip the wire slightly longer than the ferrule’s metal barrel length. Insert the wire into the ferrule until the insulation hits the ferrule’s collar. Place the ferrule into the crimping tool’s jaws and crimp fully (the tool will typically make a complete square compression around the ferrule). The result should be a tight crimp with the wire strands compressed within the ferrule and no stray strands poking out. The ferrule’s insulated collar should remain intact and help guide the wire into the terminal later. Ferrule crimps are generally straightforward – just make sure to choose the correct ferrule size for the wire; too loose and it won’t crimp properly, too tight and the wire won’t fit in to begin with.

Why Ferrules: Ferrules aren’t usually required by U.S. electrical code, but they are very common in Europe and in high-end applications for reliability. They prevent stray strands and ensure a solid connection under screw clamps. If you have a multi-stranded wire that will be inserted into a terminal block or screw-down connector, using ferrules with a ferrule crimp tool can improve the longevity and quality of the connection (no more periodically re-tightening screws that have crushed strands). The ferrule effectively turns a stranded wire into a solid pin while still retaining flexibility before the pin – the best of both worlds.

Crimping Spark Plug Wires (Ignition Terminals)

Spark plug wires (high-voltage ignition cables in vehicles) have a unique construction and require special terminals and tools. These wires typically have a graphite or spiral-wound conductor with a thick insulation and an outer jacket. The terminals (ends) that attach to spark plugs or coils are usually open-barrel style connectors that get folded/crimped over the wire. Often they also incorporate crimping over the wire’s insulation or an inner core for strain relief.

Tools: For crimping spark plug wire terminals, you’ll need a spark plug wire crimper or an ignition terminal crimp tool. Some generic open-barrel crimpers include dies for common spark plug terminals (usually for 7mm or 8mm wires). These can look like a crimping die with a curved or arched profile that folds the terminal tabs over. Haisstronica, for instance, offers a Spark Plug Wire Crimping Tool (8.5mm Ratchet Wire Crimper) specialized for this job. If you only occasionally crimp spark plug leads, some inexpensive ignition wire crimping pliers are available, or even a die that fits in a vise or can be struck with a hammer (in a pinch). However, for best results a ratcheting spark plug crimper tool is recommended for even pressure.

Technique: The process typically involves first stripping the ignition wire – often you don't strip it like a normal wire; instead you fold the conductor back over the wire’s insulation. For example, with many spark plug terminals, you’ll strip about 1/2 inch of the insulation (sometimes leaving an inner core intact depending on wire type), then fold the conductor strand(s) back. The metal terminal is placed onto the wire, with one set of tabs catching the exposed conductor and another set of tabs meant to crimp onto the insulation or inner core. You then crimp the terminal using the appropriate cavity of your tool: usually one crimp squeezes the conductor tabs firmly onto the conductor (creating the electrical connection), and another crimp (or the same motion if the die is designed so) folds the larger tabs onto the insulation for strain relief. The end result should look like factory-assembled wires: the conductor is tightly pinched between the metal tabs, and the wire is firmly secured so it won’t pull out. After crimping, the terminal is often inserted into a rubber boot that connects to the spark plug or coil. Always give the finished terminal a tug test – a spark plug wire sees a lot of vibration and heat, so the crimp must be very secure. If done right, a crimped spark plug wire will be as reliable as the originals.

Note: Spark plug wire crimping can be a bit tricky for first-timers. It’s worth practicing on a spare wire. Also, because these carry high voltage but low current, maintaining a good clean connection is key to preventing misfires. Never solder spark plug wire terminals (solder can interfere with the conductor core and add resistance; plus it makes the connection rigid). A proper crimp is the recommended method, even by ignition wire manufacturers.

Crimping Large Battery Cables (Battery Lugs)

When dealing with very large wires (for example 8 AWG and larger, like 4 AWG, 2 AWG, or 1/0 gauge used in car battery cables, audio power runs, or solar battery banks), the typical hand crimpers for small terminals won’t work. These thick cables use heavy-duty lug terminals or splice connectors that often require a much higher crimping force and a different style of crimp.

Tools: For battery cable lugs and similar large terminals, you generally need a heavy-duty crimping tool. There are a few options:

• Hexagonal Crimpers: These are ratcheting or hammer-operated tools that crimp a lug into a hex shape. They often resemble large bolt cutters or use hammer blows or hydraulic force. Handheld hammer crimpers (where you place the lug and wire in a tool and strike it with a hammer) are a budget option. There are also hydraulic crimpers (often affordable hand-pump types) that can handle very large sizes and form a solid crimp.

• Indent Crimpers: Some tools press a simple indented notch into the lug. For example, a stake-type crimper used with a big hammer or hydraulic press puts a dent in the side of the lug, pinching it to the wire. This works but may not be as uniform as a hex crimp.

• Professional Crimp Presses: In industry, large cables are crimped with powered crimp presses or hydraulic bench tools, but for DIY an inexpensive hydraulic hand crimper will usually suffice for cables up to 1/0 or 2/0 AWG.

Technique: Prepare the cable by stripping enough insulation so that the bare wire can fully insert into the lug (typically the lug barrel is maybe an inch long, so strip a bit less than that). Important: For very fine-stranded cables (like welding cable used in car audio or solar setups), sometimes people tin the strands to keep them together – but do not tin if you plan to crimp the lug. Just like smaller wires, you want the copper strands bare so they can cold-weld with the lug when crimped. Insert the cable into the lug; make sure all strands enter and the wire insulation butts up to the inside end of the lug barrel. Place the lug in your crimp tool according to the tool’s instructions (e.g., in the correct size groove). Activate the tool (pump the hydraulic crimper, swing the hammer, etc.) to deform the lug onto the wire. A good crimp will visibly compress the lug — you’ll usually see a hexagon shape or a pronounced indent. The wire should be tightly locked in place. Often, the lug will have a slight bulge of metal where it was displaced. Many lugs have an inspection hole; you might see a bit of wire or solder peeking (some people add a bit of solder after crimping large lugs as a belt-and suspenders approach, but if the crimp is properly done, solder isn’t necessary and can even be harmful in high-vibration environments). After crimping, seal the connection by sliding a piece of heavy-duty heat shrink over the joint (ideally adhesive-lined heat shrink for weather protection) and shrinking it. This covers the lug barrel and a bit of the cable insulation, providing strain relief and corrosion resistance. For battery terminals especially, sealing is important to prevent acid fumes or moisture from corroding the copper.

Safety Tip: When crimping large gauge cables, ensure the cable is held securely – sometimes the crimping action can make things jump or shift, especially with hammer blows. And of course, never crimp live battery cables; disconnect batteries before working on their cables.

Crimping large lugs takes some effort but yields extremely robust connections capable of hundreds of amps, which soldered joints might not handle as well due to heat. A properly crimped battery cable lug will have low resistance and will not overheat under load.

Crimping Open-Barrel Terminals (Non-Insulated Pins)

Open-barrel terminals (also called F-crimp terminals) are very common in automotive connectors, electronics pin connectors (like Dupont style pins for breadboard wires, RC servo connectors, ATX PC power supply pins, etc.), and many OEM wire harnesses. They are called “open barrel” because the metal terminal has an open U-shape that the wire sits in, and the crimping tool folds the “ears” of the U over the wire and insulation.

Examples: This category includes things like Molex KK or ATX power supply pins, Weather-Pack and Metri-Pack automotive connector pins, JST-VH/XH series, etc. If you’re adding new pins to a car’s wiring connector or making custom PC fan cables, you’re crimping open-barrel pins.

Tools: You will need a non-insulated open-barrel crimper designed for the specific size range of your pins. These typically have two crimping sections in one die: one for crimping the stripped wire portion, and one for crimping the insulation support wings. The die often has markings like 22–18 AWG, 16–14 AWG, etc., and may crimp both the insulation and conductor in one action (if it’s the right style) or you may crimp in two steps with different sections of the die. There are universal open-barrel crimp tools (often looking like a parallel jaw or ratchet crimper with several slots) that can do a decent job on many common terminals. For very small terminals (like those in computer connectors), be sure the tool is rated for that size.

Technique: The process is similar to regular crimping but with more attention to detail:

1. Strip a small length of insulation from the wire – usually only ~2–3 mm (0.1") for small terminals. These pins have very short barrels.

2. Place the terminal in the crimper die before inserting the wire (this helps position it correctly). Many open-barrel crimpers have a ratchet that can hold the terminal in place lightly.

3. Insert the stripped wire into the terminal from the back, so that the bare wire lies in the metal U-barrel and the insulation is under the longer set of wings at the back of the terminal.

4. Squeeze the crimper to crimp. Ideally, the tool will curl the shorter set of metal tabs tightly around the bare wire (making the electrical crimp) and simultaneously crimp the longer tabs around the insulation (providing strain relief). The end result: the conductor is secured and the insulation is gripped so the wire can’t easily flex at the termination.

5. Inspect closely – open-barrel crimps are small and precise. The conductor crimp should form a neat tight wrap around the strands, and the insulation crimp should lightly hold the insulation without cutting into it.

Open-barrel terminals often intimidate beginners, but with the right tool, it becomes routine. It’s crucial to use the proper size terminal for your wire and the matching die. For example, if you try to crimp a very small pin in too large a die section, it will deform incorrectly. Conversely, forcing a too-large wire into a tiny terminal will jam or not crimp fully.

Common mistake: Not all crimpers crimp both the insulation and conductor in one go – some cheap ones require two separate crimps. Read your tool’s instructions. If doing two crimps, always crimp the conductor part first, then the insulation part. Additionally, avoid soldering these pins after crimping; manufacturers advise that solder can make the joint brittle. A properly crimped open-barrel pin is gas-tight and strong without solder.

Other Connector Types

There are many other crimp-style connectors (coaxial cable connectors like BNC, RJ45 Ethernet plugs, fiber optic termini, etc.), each with specialized tools. Covering them all is beyond the scope of this guide, but a general rule is: if it’s a crimp connector, invest in the correct crimping tool for that connector type or a die set that fits your multi-function crimper. Using the wrong tool can ruin the connector and the cable.

One notable connector for solar power systems is the MC4 solar connector. These require crimping the pin inside with a dedicated MC4 crimping tool (often included in solar connector kits). If you’re setting up rooftop solar panels, a ratcheting MC4 crimper will ensure those connections are secure and weatherproof.

In summary, choose your tool according to the connector. There is a great variety of electrical crimpers tools out there – from general-purpose to highly specialized. Understanding the type of connection you need to make will guide you to the right tool and method. Next, we’ll address some frequently asked questions related to crimping wires.

FAQs on Crimping Wires

Q: Is it better to crimp or solder wires?
A: For most electrical connections in vehicles, appliances, and electronic devices, crimping is preferred over soldering. A proper crimp, done with the right tool and connector, creates a mechanically robust and electrically sound joint that is often referred to as a cold weld. Crimped connections handle vibration and movement much better than soldered ones, because solder can make a wire joint inflexible (and soldered connections can crack under vibration or wicking of solder can cause wire strands to break). In fact, many industries (automotive, aerospace) prohibit soldering critical wire terminations – they require crimps. According to connector manufacturers, adding solder to a crimp can actually reduce reliability, since a good crimp is already air-tight and very strong on its own. Soldering a crimped connection can also introduce heat damage or make the joint brittle. The bottom line: use a quality crimp for reliability; solder is generally reserved for circuit board work or tinning large cable ends prior to lug attachment (and even then, not when a crimp is involved). If you perform the crimp correctly, no solder is needed or desired.

Q: Can I crimp wires without a crimping tool (for example, using pliers)?
A: Technically, you might manage to deform a connector with pliers or vise grips, but it’s highly unreliable. Pliers cannot apply the controlled, evenly-distributed force that a crimping tool can. The result is often a poorly formed crimp that can easily come loose or have high electrical resistance. In an emergency, some people have used a hammer and punch or pliers for very basic crimps, but these connections should be redone properly as soon as possible. If you’re doing any serious amount of wiring, invest in a decent wire crimper. Even an affordable ratcheting crimper will make a world of difference in the consistency and quality of your connections. Remember, a bad crimp can lead to intermittent connections, heat buildup, or wire pull-out – which can all cause bigger problems (equipment failure, shorts, even fires). So, while it’s possible to improvise, it’s not worth the risk. Use the right tool for peace of mind and professionalism.

Q: What size crimping tool do I need for my projects?
A: It depends on the range of wire sizes and types of connectors you plan to work with. For general DIY and automotive use (say 22–10 AWG range, and common insulated terminals), a standard ratcheting crimper with multiple die positions (often color-coded red/blue/yellow as discussed) will cover you. This would handle things like speaker wires, automotive harness repairs, appliance cords, etc. If you plan to also do small electronics (down to ~26 AWG) or larger cables (up to ~8 AWG), check that the crimper supports those ranges or consider getting an additional tool for the extremes (for instance, a small precision crimper for tiny Dupont pins, and a heavy lug crimper for battery cables). Some crimp tools come with interchangeable dies, which is great if you have diverse needs. For example, one frame might let you swap in a ferrule crimping die, an open-barrel die, and an insulated terminal die. Electricians often have a few crimpers: one for general wiring terminals, one for ferrules, one for coax or data connectors, etc. Also, consider if you need a crimping plier for uninsulated terminals versus insulated – some tools do both, others are specific. In summary: start with a quality ratcheting wire crimping tool covering your most common wire range. You can add specialty crimpers as needed when you encounter new connector types.

Q: Are there any standards or certifications for crimped connections?
A: Yes, in professional settings there are standards (IPC/WHMA-A-620 for cable harnesses, NASA workmanship standards for aerospace, UL standards for electrical connections, etc.) that outline what a proper crimp looks like and how it should perform. Some key points from standards: use the specified tool and connector as a pair, the crimp height (a measurement of the crushed terminal) should be within a certain range, and visually there should be no exposed strands or over-crimping. One notable requirement (as mentioned earlier) from such standards: stranded wire must be used (no solid) and never crimp tinned (soldered) wire. While as a DIYer you might not be formally measuring crimp dimensions, it’s good to be aware that there is a right way that yields a gas-tight connection. Following the guidance in this article gets you very close to meeting those pro standards. If you’re doing work that needs to be inspected or certified (house wiring, aviation, etc.), be sure to follow the specific code or standard relevant to your field, but generally that means using UL-listed crimp connectors, the matching crimp tool, and doing it as instructed by the manufacturer.

Q: Can I reuse or reposition a crimped connector if I messed up?
A: No, you should not reuse a crimped connector. Once a connector has been compressed, the metal is deformed and will not crimp correctly a second time. If a crimp is improperly done (for example, wire wasn’t fully inserted or the crimper was on the wrong setting), cut it off and use a fresh connector. It may feel wasteful, but trying to salvage a bad crimp can result in a dangerously weak connection. The cost of a new connector is nothing compared to potential damage from a failed electrical connection. Likewise, if you crimp onto the wrong wire or need to change something, remove the entire connector (don’t try to pry open and re-crimp). Always carry a few extra connectors so you can afford to lose one or two during a project. On a related note, if you crimped something and then need to disconnect it (for example, you crimped wires together with a butt splice but later need them separate), you’ll have to cut it out and use new connectors or an alternative method; crimp splices are permanent connections.

Q: Why do my crimped connections still fail or come loose?
A: If you find that your crimps are failing (wires pulling out, or electrical issues like intermittency or heating at the joint), it likely boils down to one of the issues we’ve discussed:

• Using a wrong/cheap tool that isn’t crimping fully or in the right form.

• Wrong connector size for the wire.

• Not crimping firmly enough (or tool out of calibration).

• Crimping onto poor quality connectors where the metal may be too thin or not plated (prone to corrosion).

• Or in some cases, extremely harsh conditions (for instance, constant flexing of the wire right at the crimp without strain relief).

To troubleshoot: inspect the failed crimp. If the wire pulled out, either the crimp was too loose or not made in the correct location. If the wire broke right next to the crimp, perhaps the crimp was too tight (over-crimping can sever some strands or cause a stress riser) or the wire was flexing at that point (consider adding heat shrink for strain relief in the future). If the connection became green or corroded, moisture probably got in – using adhesive-lined heat shrink connectors or sealing the connection would help. In essence, go back to basics: use the proper crimping tools, good connectors, and follow the techniques outlined above, and failures should be exceedingly rare. A correctly crimped connection is very robust – many cars on the road have crimped wiring that lasts decades. So if yours aren’t lasting, re-examine your process.

Hopefully these FAQs clear up any remaining doubts. Crimping is one of those skills where a little knowledge and the right tools go a long way. It might feel unfamiliar at first, but once you get the hang of it, you’ll appreciate how quick and effective crimped connections are.

Conclusion

Crimping wires properly is key to creating electrical connections that stand the test of time. When you crimp a wire with the correct technique, using a quality crimping tool and matching connector, you create a secure mechanical bond and an excellent electrical pathway. This bond is often as good as a welded connection – it won’t shake loose, corrode, or degrade when done right. By now, you should understand the essentials of how to crimp wires: prepare the wire, choose the right connector, use the appropriate wire crimper (preferably a ratcheting crimper for consistent results), and inspect your work. We covered special cases from ferrule crimping to heavy-duty cables, so you can tackle projects ranging from delicate electronics to automotive wiring and beyond.

In summary, always remember to avoid common mistakes (like using the wrong size or crimping improperly) and don’t cut corners with makeshift tools – a proper crimp tool is a worthwhile investment for anyone who does electrical work regularly. If you’re an American DIYer working on your car or home, or a professional electrician, following these guidelines will ensure your crimps are safe and long-lasting. And if you need the tools to get started, Haisstroncia offers reliable options like the Ratchet Wire Terminal Crimping Tool for AWG 22-10 (mentioned earlier) to make the job easier and more precise.

With solid crimped connections, you’ll have confidence that your wiring jobs – whether it’s wiring up a new sound system, repairing a trailer harness, or building a custom battery cable – will perform flawlessly for years. Happy crimping!

Don’t forget to check out our Ratchet Wire Terminal Crimping Tool for AWG 22–10 Heat Shrink Connectors – a versatile crimper that covers most common wiring needs for DIY and professional projects.