How To Join Stranded Copper Wires Without Soldering

Disclaimer: I’m usually wiring up 12V DC, these tips are not for the high voltage AC stuff.

So you have your project, maybe it’s a car or a cafe racer project like me, and you want to do all this cool stuff to it. Maybe wire up new headlights a new speedo.

Well if you want to do all that cool stuff, you have to know the basics first.

I was a bit embarrassed to realize that I had no idea how to wrap copper wires. couldn’t wrap wires in a way that was clean, and strong. I had no idea what soldering and crimping were either.

So that’s what the next few articles will be able, joining wire together!

In this article, I’ll be showing you a few common wiring techniques you can use to splice wires together, that are strong and conductive. I’ll able be to test the strength of each of my splices to show you which has the best durability.

What does splicing wires mean?

Splicing wire is the process of joining two or more pieces of wire together to make a single conductor. This process is done so that the current can flow the entire length of the wire.

There are a few ways that you can splice wire- twisting copper wire together without solder, with soldering, and crimping.

Reasons not to use soldering?

A common reason not to solder is when the wire is exposed to movement or vibration. Soldering makes a joint more brittle, so there is a risk that it could break if in a position where it is subjected to frequent movement. In these cases, twisting to copper wire together or crimping are fine solutions.

First of all, despite what you might read online, it’s not the end of the world if you do not use soldering. Sure, soldering will provide a stronger splice with better conductivity, but there are cases where you might not want to use soldering or it’s not practical.

The internet is full of subjective opinions. One blog might say you must always solder, while another YouTuber will say that it really “doesn’t matter, just throw some electrical tape on it and move on”. The answer is somewhere in the middle. 

Tools you need for splicing wire

Here’s a list of tools you’ll need to get the job done:

  • Copper Wire
  • Wire Stripping tool (or a blade)
  • Heatshink tubes or electrical tape.
  • Lighter, or heatgun (if using heatshrink)
  • Needle-nose plyers (optional)

How to strip insulation off a wire? 

The easiest method for stripping wire is to use set wire strippers or multifunctional wire cutters. These tools are great for fast, predictable results.

Before we can start joining wire together we need to strip the ends to reveal the copper. Here are four ways you can strip insulation:

  • Wire Strippers (preferred)
  • Multifunctional Wire Cutters (preferred)
  • Plyers
  • Sharp Blade

If you have a steady hand you can use a sharp blade or some pliers to cut the insulation and pull the plastic directly off with your hand or a set of pliers. It’s a personal preference, but I prefer not to use these methods as it’s easy to cut strands of copper and reduce the efficiency of your join.

Method #1: Western Union/Lineman splice

  1. Cut roughly an inch of insulation off your wires
  2. Twist the ends of each wire tightly
  3. Slide the heat shrink through one of the wires
  4. Bend each wire to 90 degrees and interlock
  5. Coil each wire around the other three times
  6. Trim off any excess strands
  7. Apply heatshit tube

While this method is fine for most situations, for stranded copper, it’s not as strong a splice as the Interweave or Racecar Methods below. This method is best suited with the combination of soldering and solid core wire. In fact, it’s the chosen method by NASA.

For the type of wire I was using, I found that I preferred the interweave splice over the lineman splice, which is up next.

Method#2: Interweave Splice

I call this one The Interweave Splice. I found it to be a strong and clean splice thus an excellent way to join stranded copper wire without solder.

How to do the interweave splice:

  1. Twist about one third of the length of exposed wire from the base of insulation.
  2. Apply heat shrink to one of the wires
  3. Fan out the remaining copper strands on each wire.
  4. Interlock the strands.
  5. Twist the ends of the strands together to form an ‘X’ pattern.
  6. Loop the remaining copper around the other at least 3 times.
  7. Trim off any excess copper.
  8. Apply heat shrink or electrical tape.

To make this join even stronger and more conductive, solder the splice before applying heat shrink.

Method #3: The Racecar Twist

Shoutout to Steveston Motor Co for this handy method.

This is another great method for a strong connection, but it does require extra folding of the wires so it is suited for wires that have a smaller diameter (higher gauge).

  1. Cut a little over an inch of insualtion
  2. twite the strands of each wire to for a single strand
  3. Fold the two interlocked wires in half
  4. Fold the wires agen to be poarallel with the main wire
  5. Apply heat shrink

A couple of tips to get this one. I’m using 16 gauge wire, and the results were fine. Make sure you select the right size of heat shrink and consider adding extra silicone in the heat shrink tube to make it water-tight.

Can I use electrical tape for exposed copper wires?

A common question that pops up when we are at the stage of insulating the wire is if you can electrical tape for exposed copper wires.

Yes, but use a reputable brand with high thermal properties. Electrical tape is best used as a solution to cover small cracks and damages to the insulation of the wire The application technique is also important to consider when wrapping wire with electrical tape so that it does not come undone easily in the future.

Because the electrical tape is less durable, heat shrink is always my go-to for wire insulation when joining copper wires.

Results: Which is the Best Join?

My personal preference is the Interweave splice. For a couple of reasons.

In my testing, the Racecar method turned out to be a slightly stronger join when I really tested breaking the wire. However, the Interweave splice was still really strong.

The interweave will work with other gauges- whereas the Racecar might be a little hard to do on lighter wires, so pay attention to that. It will work with most gauges. I would use the racecar on a lighter gauge wire so the fold is not as prominent and the heat shrink fits easier.

And lastly, the interweave is aesthetically more pleasing, smaller, no bumps. So it’s your wire is exposed that might be something you consider.

But like I said, it’s subjective. It really comes down to the gauge of the wire and the purpose.

Now over to you, what technique do you think is best? Leave a comment below!

Where To Next?

The next logical thing to do is make out join even stronger. So up next I will introduce you to the world of soldering.

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Written By Tim M

I’m on a journey to learn all I can about electronics - and I’m sharing everything. If you like my content, check out my Honda CX500 Restoration Project

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