Wiring Tutorial: Connecting 4 AWG Tinned Lugs


Working with larger gauge wires like 4 AWG can be intimidating, especially if you’re unfamiliar with the process of crimping lugs.

However, with the right tools, techniques, and a bit of knowledge, it’s definitely a skill that can be mastered. In this tutorial, we’ll guide you through the essentials of connecting 4 AWG tinned lugs, with a specific emphasis on safety and a focus on achieving a strong, dependable connection.

Why Tinned Lugs?

Standard copper lugs are prone to corrosion, especially in humid or marine environments. 4 AWG Tinned Lug offers a layer of tin over the copper, providing superior corrosion resistance and a more durable connection over time. They are the ideal choice for projects where your wiring will be exposed to the elements.

Essential Tools and Materials

  • 4 AWG Wire: Ensure you have enough high-quality 4 AWG wire for your project.
  • Tinned Copper Lugs: Choose lugs appropriately sized for your wires and the terminals you’ll be connecting to.
  • Wire Stripper: A good wire stripper is essential for accurately removing the insulation without damaging the wire strands.
  • Hydraulic Crimper: A hydraulic crimper is preferred for 4 AWG and larger wires, as it delivers the necessary force for a secure crimp.
  • Heat Shrink Tubing: Use heat shrink tubing with an adhesive liner to seal the connection and prevent moisture ingress.
  • Heat Gun: A heat gun is used to shrink the heat-shrink tubing around your crimp.
  • Safety Gear: Gloves and eye protection are recommended during the crimping process.

Step-by-Step Guide

  1. Prepare the Wire: Put on your gloves and eye protection. Use your wire stripper to remove approximately 1/2 inch to 3/4 inch of insulation from the end of the wire, making sure not to cut into the individual strands.

  2. Choose the Correct Lug: Select a tinned copper lug with a wire hole that snugly fits the 4 AWG wire. Ensure the stud hole on the lug matches the terminal where it will be fastened.

  3. Insert Wire and Pre-Crimp: Gently twist the strands of the exposed wire and insert them fully into the lug’s barrel. If you have trouble, a little bit of twisting or tapering the strands can help them go in. Use your crimper to make a preliminary crimp to hold the lug in place.

  4. Crimp the Lug: Position your hydraulic crimper to deliver an appropriately sized hexagonal crimp onto the lug. Apply steady pressure until you hear/feel the crimper release. A good crimp will be solid and secure, creating a cold weld between the wire and the lug. For optimal results, make two crimps.

  5. Inspect the Crimp: Examine the connection closely. The wire strands should be completely fused with the lug material, with no gaps or loose strands visible. Perform a firm tug test to ensure the wire won’t come free from the 4 AWG Tinned copper lug.

  6. Apply Heat Shrink Tubing: Slide the heat shrink tubing over the crimp connection, ensuring it extends over the wire’s insulation as well. Using your heat gun, carefully apply heat until the tubing shrinks securely around the connection, and the adhesive melts slightly to create a watertight seal.

Important Considerations

  • Crimper Selection: Using the correct crimper type and die size is crucial for a secure crimp. Many hydraulic crimpers have interchangeable dies –  consult the manufacturer’s instructions for your specific crimper to ensure you’re using the correct die size for the lug you’ve chosen.  A mismatch between the die and the lug can result in a weak crimp that can lead to electrical problems down the line.
  • Cleanliness: Keep the wire strands and the interior of the lug free from dirt, oil, and other contaminants to ensure a good electrical connection. Contaminants can act as insulators, increasing resistance at the connection point and leading to overheating. You can clean the wire strands with a wire brush or a cotton swab dipped in rubbing alcohol.
  • Corrosion Prevention: Using tinned lugs is the first step in preventing corrosion, but a good crimp and a well-sealed connection are equally important.  A secure crimp creates a tight connection between the wire strands and the lug material, minimizing the gaps where moisture and contaminants can accumulate. Sealing your connections with adhesive-lined heat shrink tubing provides an additional layer of protection against corrosion by creating a watertight barrier around the connection.  When choosing heat shrink tubing, select one with a diameter slightly larger than the lug barrel after crimping to ensure complete coverage.


By following these steps and understanding the concepts, connecting 4 AWG Tinned copper lugs can be done safely and effectively. With practice and the right tools, you’ll be able to create reliable wiring connections that can withstand harsh conditions and the test of time.