How to Solder 3 Wires Together: A Few Things to Know

Soldering is the mainstay of any electrical and electronic project. The simple welding technique binds metals together to form electrically conductive joints in a way where you can easily detach them later if necessary. You can solder any metal objects together, even wires to other wires.

The process for soldering 3 wires together is the same as splicing 2, 4, or even 10 of them. You interweave the threads of the wires together before soldering the joint solid. The challenge is holding the wires in place long enough for the solder to cure.

You must also ensure your soldering equipment is worthy of the task. Wires come in different sizes and construction. You need the right solder and stripping tools before you tie your wires into a knot. Keep reading to learn everything you’ll need to know before soldering those wires.

Soldering Multiple Wires Together

Simple to understand as a concept, soldering can challenge even time-hardened veterans. The low-heat welding technique can do more harm than good if not done correctly. While you can avoid most of the issues using a printed circuit board as a bridge, there is a lot that can go wrong when you must splice two or more wires together directly. 

The key component is understanding how and when to apply solder or a metal-alloy binding agent. If done properly, this solder will create a strong, reliable electrical connection between your wires. Most solder variations can also withstand high amounts of current while remaining corrosion-free, making them great for power and signal transmission applications. 

Soldering Equipment

Before you can solder your wires together, you must first gather the equipment you need. Luckily, there are no special tools required for splicing wires. You can use the standard equipment found in any electronics store. 

Solder

At the base level, soldering uses a binding agent called a solder to make connections. This solder is a unique, quick-cooling metal alloy that comes in numerous alloy concentrations within several categories. The most common of these categories are lead, lead-free, and silver

You can also choose a solder with or without a flux core. Flux makes the material mechanically and electrically stronger, but it also comes with a higher price. 

Either way, you want to avoid silver solder and acid flux. Silver solder is for traditional non-electrical welding and could damage your electrical equipment. Acid flux can eat the plastic insulation around your wires leading to shorts and possible fires. Luckily, the most popular consumer solder is a lead-free tin and copper alloy with a rosin core

Soldering Iron

You need a soldering iron to apply solder to your wires. This hand tool uses a standard 120-volt AC to melt the solder across the gap between tire threads creating the electrical connection. 

You can find them in several form factors such as a gun or a pen, letting you choose the format the best matches your skill and style. However, you want a 15-watt or a 30-watt soldering pen if you are new to the world of soldering. 

You also want your iron to have the right tip or replaceable end piece. The most common tips are:

  • Conical tip: A fine, pointed tip meant for precision electronics soldering, especially in small spaces
  • Chisel tip: A broad flat tip best suited for soldering wires and other large components together

Soldering Iron Stand

While not required, you might want a soldering iron stand to go with your soldering iron. Irons get hot enough to ignite nearby flammable materials. A stand reduces your risks from accidental injuries and fires. 

Soldering Station

For many soldering jobs, you can go with a simple iron. However, if you plan on doing several soldering projects, you should invest in a soldering station. Soldering stations are complete soldering kits. They provide temperature-adjustable soldering irons with a dedicated stand. These devices also come with temperature sensors, cleaning sponges, alerts, and password protection. 

Brass or Regular Sponge

Another optional but important soldering tool is a sponge or a cloth for cleaning the tip. You can use a regular wet sponge for this cleaning. However, such measures reduce the tip’s lifespan, which contracts and expands from the moisture and cold temperature. A damp brass sponge tailored for cleaning electronics will mitigate these effects. 

Helping or Third Hand

Because you want to solder wires together, you will want something to hold them in place while applying your solder to them. You can rig something together yourself, but you can use a pre-made helping hand tool. These tools provide 2 or more alligator clips that keep your hands free for soldering. Some models even offer a magnifying glass to help you see what you are doing. 

Desoldering Braid or Solder Sucker

A desoldering braid is a fine woven wick that sucks up liquid solder. You use it like solder by pressing it against the joint with a hot soldering iron. It is a great tool that everyone should have in their soldering kit.

A solder sucker is a mechanical vacuum that acts like a desoldering braid. You first heat the solder and then run the sucker over it. It is an excellent tool if you have a lot to remove. 

Soldering Safety Precautions

Now that you have your tools and the basics, you must consider several safety precautions before pressing your soldering tip to your cables. Soldering irons can easily get as hot as 800 degrees Fahrenheit. Solder also releases harmful fumes as it melts. 

Some useful safety tips include:

  • Always wear protective glasses near your work area to prevent accidental solder splashes from reaching your eyes
  • Do not touch the tip when the iron is hot or lay the iron on something flammable
  • Do not solder near flammable objects
  • Pay attention to where you point your iron
  • Solder over a non-flammable tray to catch any solder that drips down
  • Do not breathe solder smoke
  • Use a fan or solder in a well-ventilated, outdoor location
  • Thoroughly clean your hands and your work area after you finish soldering

Preparing and Soldering Your Wires

Now that you have your equipment, you can start splicing your wires together. Because the same procedures work with any number of wires, our examples will deal with splicing two wires. Adjusting the steps for the third wire is easy enough. You can probably do all three at once if you are careful.

Prepare Your Workstation

Your first step when soldering anything is to prepare a workspace for it. It is as simple as placing all the equipment you need for your project where you can reach it. For instance, you want your helping hands set up right in front of you with your soldering station off to your dominant side. This way, you will have control over your equipment without blocking your view.

Strip the Wires

The next task on your list is to strip the ends of your wires. You want to remove enough insulation so that you can easily manipulate the coper threads inside. There is no wrong length to strip as long as you strip all wires to the same length. If you make a mistake and cut the wire threads, you can remove the damaged ends and start again. 

You can strip the wires with a knife or with a wire stripper. You can use any sharp knife, but you must make sure you cut your wires at a small angle towards the tip of the cable. You want to file through the insulation until you can remove the threads. At which point, you want to remove the insulation and cut it off completely.

While a knife works, you will find a wire stripper is easier to use. With a knife, you can accidentally cut the wire along with the insulation. A wire stripper gives you more control, letting you cut and remove the cable’s outer layer in a single stroke. 

However, you must use a wire stripper tailored for your wire’s gauge. The wrong gauge setting can cut through the wire or leave too much insulation. Luckily, you can get an automatic wire stripper, which will set itself for you. 

Mesh the Wire Leads Together

With your wires stripped, it is time to bind them together. The first step in the process is to mesh them together into a single mass of copper. This is the most critical step in the process. So, you want to take it slow. If you mess things up here, you will ruin your project.

Meshing two or more wires together is as simple as spreading out their threads and then interweaving them together. The current flows through each strand. So, you have some room for error, but you want to ensure you cannot easily pull the wires apart. You can use this process on all your wires at once. You just crisscross them at angles to each other.

After creating the mesh, you must twist it tight. The motion is like tying a shoelace. You make an “X” out of the wire and then wrap one wire end around the others. You continue the motion until you run out of stripped wire. Once done, no copper threads should stick out. Everything should be flush to what is now an electrical joint. Any copper that sticks out can cause shorts and other problems later. 

Once complete, you are ready to solder the joint solid. But first, you may want to use a helping-hands harness or a set of clamps to hold the wires in place. Any movement could jiggle the mesh loose and ruin everything. You do not need it, but many experts recommend applying a heat shrink to the alligator clips to prevent them from eating through your wires. 

Tinning the Soldering Iron Tip

With your wires ready to go, it is time to move to the soldering iron. Depending on your model, you either just plug it in or turn a knob, but you must clear it of rust and damage by tinning the tip. 

Tinning applies a layer of solder to the tip to improve heat flow, producing a more even heating of your soldering target. It also protects the time from wear and rust. It is also a simple process. 

  1. Ensure the tip is securely attached to the iron
  2. Plug or turn on the soldering iron to heat it to around 752 degrees Fahrenheit, which should take a minute or two
  3. Wipe the tip clean with a damp, wet sponge
  4. Let the tip heat up again
  5. Touch a line of solder to the tip and let it flow, and coat the tip evenly

You should complete this process before and after each soldering session. 

Apply Flux and Solder to the Joint

The next step is preparing your wire joint for solder by heating it. If your solder does not have a flux core, you can begin the process by coating your wire joint with rosin flux. The flux will help the solder seep into the wire threads to ensure stronger bonds. You can skip this part if your solder comes with flux inside. 

Heating the Wire Joint

Either way, your next task is to heat the joint from below with the iron tip for about 3 to 4 seconds to prepare the wires for the solder. Thicker wires may take longer to heat up, but you can speed up the process by feeding solder between the iron and the wires.

Once hot, you then move the solder to the top of the wire joint and let it melt and flow around and through the joint. As you do not need a lot of solder for this, it should only take a few seconds at most for the solder to thoroughly coat the wire strands. 

To prevent solder blobs, you must remove the iron and solder from the wires as soon as you see the solder completely engulf the wires. You should then let the joint cool and harden before touching it. In the end, you should see outlines of the strands, but there should be no bare copper.

Inspect the Joint

With the soldering done, it is time to give your 3-way wire joint a final inspection. You want the solder to coat through all wires with no globs. The outlines of the outer wire strands should be visible. If something seems off, you can desolder the joint and redo the process. 

Cover the Joint in Heat Shrink

A bare wire is a disaster waiting to happen. Therefore, you must enclose your newly soldered 3-way wire joint to prevent shorts and accidental electrocutions. Remember, your wires are a part of a live circuit. 

You can use any insulating material to cover your joint, including electrical tape. Good quality electrical tape is rarely available to consumers. Your best solution is to use heat shrink tubing instead. It is readily available and easy to use. 

Pay attention to the type of shrink tubing you use though. They come in different colors and sizes, and you want tubing that you can wrap around your wires and matches the aesthetics of your built. In other words, you want a heat shrink that fits nice and tight once heated. You also want enough to cover all the exposed wire and some insulation to ensure a proper enclosure. 

How to Apply Heat Shrink Tubing

Ideally, you may want to slide the tubing on to the wires before you start threading them together, but that is not required. You do, however, must apply the heat shrink before your soldering iron cools off. So, you want to keep it plugged in and powered on until you complete this process. 

  1. Cut the tubing until you have enough to cover all your wires, ensuring that each piece is big enough to cover the uninsulated joint
  2. If you can, slide each piece of tuning on to the wires. If you cannot, cut a small slit into each piece, which will allow you to wrap them around the wires.
  3. Coat the joint with a silicone paste or dielectric grease to make it waterproof.
  4. Once the solder cools, slide the tubing over the joint.
  5. Use a lighter or heat gun to shrink the tubing until it is flush with the wires.

Using Electrical Tape 

If you must use electrical tape, you want to get the best quality tape you can get. Avoid the cheap brands like the plague as they are junk. They are best for emergency repairs and that is it. Instead, you want 3M Super 33, Supper 88, or equivalents. These tapes create strong, firm seals around your wire joint. They also last for years before you must replace them. 

Final Cleaning and Wrap Up

If you made it this far, you have completed the soldering process. Your 3-wire connection should work as you intend it. Therefore, it is time to clean and wrap things up by re-tinning the soldering iron and then letting it cool. 

While the iron cools down, you can clean your work area and start putting away your soldering equipment. This also means removing any excess solder that dripped over your harness and wires. You can do this with the same damp sponge you used to clean the soldering iron.

Conclusion

Soldering 3 wires together seems like a daunting task, but it is quite easy in practice. It is just a slightly involved form of splicing two wires that is easily scaled as you add more and more cables to the mix. At its heart is weaving their strands together before coating them in solder. The only real challenge is keeping the connection steady long enough for the solder to bind to the wires and harden.

Source: Makerspaces

Alexander Berk

A bit about myself: I am a certified international welding engineer (IWE) who worked in different welding projects for TIG, MIG, MAG, and Resistance Spot welding. Most recently as a Process Engineer for Laser and TIG welding processes. To address some of the questions I frequently got asked or was wondering myself during my job, I started this blog. It has become a bit of a pet project, as I want to learn more about the details about welding. I sincerely hope it will help you to improve your welding results as much as it did improve mine.

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