Melt the metal, join the joints, correct the electrical connection
When fortifying your arsenal of home improvement tools, you might not think to buy a soldering kit, but these inexpensive tools can be handy for mending or improving the wire connections on electrical appliances.
With some practice, you can add soldering electrical wires to your list of handy homeowner skills— but this isn’t a job for slapdash DIYers. Soldering irons are high-temperature tools, and doing a poor or careless job can cause appliance burnouts, short circuits, or even fires. Below, our guide will teach you how to solder wires safely.
Keep yourself and the rest of the household safe by taking the proper precautions before you begin any soldering work.
Get out the goggles and gloves: Protect your hands and eyes from hot sparks and toxic materials.
Have a well-kept workstation: Soldering irons can reach over 600 degrees Fahrenheit in no time. You want to have a safe, clutter-free, non-flammable workspace.
Good ventilation is vital: Solder pastes and lead-based solder can cause respiratory issues in stuffy environments.
Try out some test runs: Practice with at least half a dozen test joints before you solder wires together on your prized appliance.
Calculate your wire diameter: You’ll need these measurements to buy the correct type of heat shrink tubing.
Turn off power to the wired appliance. Safety first.
If you’re already pretty familiar with electrical work, you can solder wires in just a few steps. Remember to use caution, take your time, and only attempt this work if you have experience.
Use your wire stripper (on the correct gauge) or a sharp utility knife to cleanly remove around 1/2-inch to 3/4-inch of the colored plastic insulation coating from each of your wires. This is the right amount to strip to ensure you can solder correctly without using too much heat shrink tubing in the next step.
Take care not to damage the wires underneath—using the correct gauge wire cutting will help here. Scraping the plating exposes copper wires to oxidation, and you can compromise the electrical connections.
Next, grab your flexible plastic tubing designed to fit snugly over the wires. Make sure you buy the proper-sized tubing. Go too large, and it won’t shrink down to fit and insulate properly after the soldering. It shrinks at least 50% when you apply heat.
Cut a length that covers the splice plus 1/2-inch on either end. Slip the tubing over one of the wires. For now, slide it down the wire so that it rests a safe distance away from the exposed area you will solder later.
Twist the wires from both sections until they interlock to help reduce cracking in the solder joint and improve its integrity. They should twist tight enough that they are smaller in diameter than the heat shrink tubing. Don’t overdo it, though—this can make it difficult for the soldering action to penetrate.
Rub a little rosin flux paste across the wire to cover the join completely. This helps to pull the solder into the connecting wire strands.
To activate the rosin flux, touch the soldering iron tip close to the wire for a couple of seconds. The heat will cause the rosin flux to melt. When it starts smoking, this means the flux is activated.
If you’ve used the iron before, clean the iron’s tip with a damp sponge to remove any lingering oxidation residue. A clean tip will maximize conductivity and produce a clean joint. If you’ve purchased a few soldering iron for this project, you can skip this step.
Next up: The fun part. Grab your protective gloves and goggles before handling the soldering iron.
Turn on the soldering iron and unroll around four to six inches of solder ready to use.
Keep the heated soldering iron in its designated stable cradle or stand when not in use to prevent any scorch damage or fire risk. Turn it off if you need to leave it unattended at any point and only grab the iron by the insulated handle.
The solder and the solder tip should match the diameter of the existing wire as closely as possible.
Press the tip of the iron against the wire meshed strands.
Hold firmly for a few seconds to allow the solder to melt onto the iron.
Touching the solder lightly against the joint should immediately combine the wire strands.
Give yourself (and the solder iron) a moment to rest. Allow the solder to cool and solidify for a couple of minutes. Leaving the wires undisturbed while it’s drying promotes a solid connection.
Pull the heat shrink tubing over the soldered connection. Let it overlap with the original insulating tubing by at least 1/4 inch on either side, ensuring all parts of the exposed wire are covered.
Finally, grab your heat gun. Use it to shrink the insulating tubing around the wire. If you don’t have a heat gun, you can run a lighter close to the tubing instead.
Having the skill to solder together two wires is a bonus when working on basic electrical repairs around your home. However, dealing with electrical connections—especially if you lack basic industry know-how—isn’t something you shouldn't tackle without the right tools and experience.
Sometimes calling in a licensed electrician near you is the safer choice. The cost to hire an electrician ranges from $50 to $100 per hour, but this is money well spent if you’re nervous about soldering wires together yourself.
Aim for a uniform, smooth joint to ensure a good electrical connection. If it looks crusty and uneven, your iron tip might be dirty or the joint isn’t hot enough. To keep the iron tip clean, wipe the tip with a damp sponge or brass tip cleaner when you spot black spots or rust to remove any oxidation and flux residue. Tinning the tip surface with a small amount of solder offers a layer of additional protection.
Soldering is a reliable and durable way to connect wires, but it isn't the only method. Nowadays, professionals often crimp the connection instead—although this requires a higher degree of skill than soldering.
Think of soldering as a permanent patch-up job. To reverse the process, you need a desoldering pump to suck molten solder through its nozzle. Rather than investing in this additional kit and hassle, it makes sense to practice your soldering technique before getting stuck into repairs on any household appliance wiring.
