Electrical connections are the backbone of any reliable system, and safety starts with a proper crimp. A poor crimp can lead to voltage drops, overheating, or even system failure. That’s why UL-rated crimps are the gold standard. They ensure your connections meet rigorous safety and performance requirements. In this guide, we’ll walk through how to create a proper UL-rated crimp using heat shrink terminals and a ratcheting crimper.
Why UL Matters
UL stands for Underwriters Laboratories, an independent safety certification organization that sets standards for electrical components and systems. When a product is UL-rated, it means it has been tested for:
- Electrical safety
- Mechanical durability
- Resistance to heat and vibration
Using UL-rated terminals and tools ensures your connections meet industry standards and comply with regulations—critical for both professional installations and DIY projects.
Before You Begin: Gather the Right Tools
A proper crimp starts with the right equipment. Using mismatched tools or low-quality terminals can compromise your connection. Here’s what you’ll need:
Chose from a variety of UL-rated heat shrink terminals to fit your application
UL Rated Ring Terminals
951065, 951085, 951105, 951385, 951565, 952065, 952105, 952145, 952385, 952565, 953065, 953085, 953125, 953145, 953385, 954105, 954125, 954145, 954385, 954565, 958105, 959105, 984105, 984120, 984145, 984385, 984565, 991084, 991105, 991385, 992085, 992105, 992145, 992385, 992565, 993085, 993105, 993145, 993385, 993565, 966415LF, 966425LF, 966435LF, 966465LF, 966475LF, 966485LF, 966495LF, 966515LF, 966525LF, 966535LF, 966545LF, 966555LF, 971065LF, 971105LF, 972085LF, 972105LF, 972145LF, 972385LF, 972565LF, 973065LF, 973085LF, 973105LF, 973125LF, 973145LF, 973385LF, 973565LF
Ratcheting crimper designed for insulated terminals like this Heat Shrink Terminal Ratchet Crimp Tool
This 120V Heat Gun from Ancor quickly and efficiently shrinks PVC, polyolefin, & dual wall, heat shrink tubing.
An Ancor Automatic Wire Stripper makes it easy to consistently cut and strip stranded wire.
Del City has a wide selection of wire to fit your needs
Having these tools ready ensures a smooth workflow and a professional result.
Step-by-Step Guide
Step 1: Strip the Wire Properly
Strip the wire to the length recommended by the terminal manufacturer—usually about ¼ inch. Avoid nicking or cutting strands, as this weakens the connection. Consider using a quality wire stripper with adjustable settings for clean, precise cuts.
Step 2: Insert the Wire into the Terminal
Slide the stripped wire into the barrel of the heat shrink terminal until the copper strands are fully seated. The insulation should butt up against the terminal’s insulation sleeve.
Step 3: Crimp with a Ratcheting Crimper
This is where the magic happens. A ratcheting crimper ensures consistent pressure and a complete crimp every time. Using a specific crimper made for heat shrink will ensure the heat shrink does not get punctured during the crimping process.
- Select the correct die for heat shrink insulated terminals.
- Position the terminal in the crimper jaws. Many crimpers will have a color coded dot to help quickly identify the proper crimp nest for your terminal.
- Squeeze until the ratchet releases—this guarantees the proper compression for a UL-rated crimp.
Why Ratcheting? Unlike standard crimpers, ratcheting tools won’t let go until the crimp is complete, reducing human error and ensuring compliance.
Step 4: Apply Heat to Shrink
Use a heat gun to shrink the terminal’s insulation. This creates a tight seal that protects against moisture, corrosion, and vibration.
Safety Tip: Avoid open flames—heat guns provide controlled, even heat without damaging the wire or terminal.
Step 5: Inspect Your Work
A proper UL-rated crimp should:
- Be firm and immovable when tugged.
- Show no exposed copper strands.
- Have evenly shrunk insulation with no gaps.
Benefits of Doing It Right
Taking the time to create a proper UL-rated crimp pays off in multiple ways:
- Safety: Prevents shorts, overheating, and electrical fires.
- Longevity: Resists corrosion, vibration, and environmental stress.
- Performance: Maintains consistent conductivity for optimal system efficiency.
- Compliance: Meets UL standards, which is often required for marine, automotive, and industrial applications.
- Professional Finish: Heat shrink provides a clean, sealed look that instills confidence in your work.
Creating a UL-rated crimp isn’t just about following steps—it’s about using the right tools and components. Heat shrink terminals combined with a ratcheting crimper deliver a professional, reliable connection every time.
Get Everything You Need at Del City
Del City offers a full range of UL-rated heat shrink terminals, ratcheting crimpers, and wire management tools to help you get the job done right.