How To: solder electrical connections

Looking to do some electrical work on your Jeep, or other overland vehicle? Be certain you’re making quality connections by soldering and properly heat shrinking your electrical joints!

I’d be a liar if I said I never ‘cheated’ and used these Scotch Lock devices to create a splice. BUT, I would be a liar if I said they work great 100% of the time.

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They work by cutting through the sheath of the wire to pinch around the copper inside. All fine in theory, but they often also cut through some of the copper wire strands. In some cases, they don’t even create a solid connection and they’re prone to moisture depending on where used.

If you use these and have problems with the lights or whatever it is you’re connecting, be certain to check these first (right after your fuse).

To improve upon the quality of your electrical work, you’ll want to solder and heat shrink most of your work. A proper splice with solder and the heat shrink creates a solid mechanical connection as well as no-fault electrical connection. Using heat shrink that is lined with adhesive helps seal moisture out of the soldered connection too.

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A proper electrical connection in your vehicle starts with stranded wire. Never run solid core wire in your vehicle. Solid core wire is meant for stationary wiring in your home. Stranded wire is more flexible for your automotive application.

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Next, you want to build a good splice between the wires you’re connecting. For most of you, this means using the “Western Union” type splice. Cut back the insulation on the wires,and wrap the two together as shown above. Don’t forget to put the heat shrink on the wire before making your splice!

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Next comes the solder, and this is the wrong way to do it. You don’t heat up the solder and try to brush it onto your spliced wires. This results in cold solder joints that simply break apart.

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Heat rises, so we place the soldering iron on the bottom of the splice and allow the wiring to heat up. Once the junction is hot enough, touching solder on the top has it quickly melt and flow into the joint. This creates a very solid splice – both mechanically and electrically.

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Once your splice has been fully soldered, slide the heat shrink tube over the joint. Hopefully you didn’t keep the heat shrink too close to the joint as you were soldering, other wise it’s already started to shrink and may not even fit!

Use a lighter, or torch attachment on your soldering iron to evenly shrink the wrap on your splice. I use adhesive lined heat shrink for most of my projects as it helps seal moisture out of your connection.

There is the basics of creating proper electrical connections in your vehicle. Yes, doing it right takes time, and you’ll be tempted to take short cuts like the Scotch locks, or even just cut back, wrap the wire and cover with electrical tape – but when you take the time, your soldered connection will last longer than the wires!

One thought on “How To: solder electrical connections”

  1. Gary says:

    Thanks for the tips.

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