How to Solder Wire to Wire Connections

Splicing Two Wires:

The ability to electrically and mechanically join two wires together is essential for all types of prototyping, maintenance, and modification of any electrical system. There are several ways to join two wires including wire nuts, Wago connectors, and crimp on terminals. However, often the sleekest, most reliable, and most robust wire to wire connection you can use, is a soldered connection with heat shrink tubing for insulation. In this instruction you will see the full process of splicing two wires together with a soldered connection.

1. Strip the Wires – Take the end of each wire that you are going to solder, and strip the insulation back about ½” back. As a beginner it is easier to work with longer stripped sections when splicing wires, but as you improve your technique, you may want to decrease the amount of wire stripped for a nicer more flexible result.

2. Cut and Add Heat Shrink – Always remember to cut your heat shrink to size and slide it over one of the wires before proceeding with any further steps. We’ve all forgotten to do this and had to take everything we just did apart, so don’t forget! Use a piece of heat shrink tubing at least a 1.5 times longer that your solder joint will be, ensuring the heat shrink is long enough to make full contact with the insulation from on both ends. For now, just slide it down one wire and keep it away from your hot soldering iron.

3. Make a Mechanical Joint – As a general rule of thumb, you should always first try to attain a solid mechanical binding of the two wires before soldering. This will improve the structural integrity of the joint and help reduce and prevent cracking in the solder joint. This can be done by simply twisting the wires together tightly until they are held in place. Sometimes a pair of small pliers can be helpful.

4. Apply Heat and Solder – Press the iron down into the wire connection to begin heating it up. When hot, apply a generous amount of solder into the connection. Remember that the iron should heat the wire and the solder melts on the wire, not on the iron. This ensures proper “wetting” as the solder wicks down into the connection to make a solid and robust joint.

5. Apply Heat Shrink – Wait for the solder joint to cool before sliding the heat shrink up over the joint. Make sure it overlaps the insulation on either side of the joint. Simply apply heat to the tubing and wait for it to shrink fully over the connection.Though heat shrink is most often shrunk with a heat gun, if you do not have access to one, a lighter may be used to the same effect. Give everything a tug to make sure it’s solid and you are finished!

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