This is Part 3 in a series of posts describing basic soldering techniques for rock-solid electrical connections.
- Part 1: Wire Stripping
- Part 2: Basic Connections
- Part 3: Tapping Wires (you’re reading it right now!)
- Part 4: Recommended Tools
Tapping Wires
“Tapping a wire” means taking one wire and connecting it to another wire, most often one that’s already connected elsewhere on both ends. This means that the connection has to be made somewhere in the middle. In this example, we’re going to use the black wire and tap into the blue wire.
First, strip away a section of insulation on the target wire. A 1/2 inch section of bare wire should be sufficient. The wire stripping technique shown in Part 1 of this series is very effective.
Next, use a sharp point or blade to separate the strands of wire.
Strip the end of the new wire and twist the exposed strands. Then, take the twisted end and insert it halfway between the strands of the wire to be tapped.
Twist the wires together.
Then, solder the connection. (Click here for a refresher course in basic soldering.)
Covering the Connection
The downside to a tap is that it’s impossible to properly heatshrink the connection without completely cutting the existing wire. If you’re unable to find a way to get heatshrink tubing over the wires, the second best option is to use a good quality liquid electrical tape. Apply several coats to the tapped joint, allow it to dry completely, then wrap with quality electrical tape. Take care to wrap each “leg” of the wire separately, as you want to avoid having any wires rubbing against each other.
The result will be a strong, worry-free, tapped connection.
Continue on to Part 4: Recommended Tools
The Latest
Recent Comments
{ 8 comments… read them below or add one }
Very nicely written and illustrated. How well does the liquid electrical tape work? I’ve have never tried it. I must admit that I usually resort to electrical tape and trying to find something to mechanically support the joint to minimize vibration. Sometimes, I’ll disassemble the connectors just to get shrink tubing over the splice.
Richard
I’ve had good results with the 3M brand liquid tape. I apply several coats, waiting until each coat is dry before applying the next. The liquid dries fairly quickly, but it takes overnight to reach full cure.
I’ve even used it to kludge a seal between copper tubing and clear plastic tubing (with water running inside both). The seal never leaked a drop.
Silicon fusion tape is a good choice for sealing this type of connection.
Something like this:
http://www.aircraftspruce.com/catalog/appages/uniwrap.php
Thanks for the tip! I’ll be adding a roll to my shopping list.
I’m trying out some of the silicone tape and it does seem to work well. It really sticks to itself really well and there is no residue. The only possible issue is the short shelf life. The manufacturer says only 12 months. I have some still on the roll that is older than that and it still seems soft and pliable.
Richard
Dear Stacy:
I have applied the technique described by you in this post extensively… But not on my motorcycle. I used it on my train layout in the basement, where I opted to changed railroad station platform lights to period pieces. As tiny as these are, there is more room for me to play with this technique than there is on my bike.
Fondest regards,
Jack • reep • Toad
Twisted Roads
I am an electronics technician and im confused, why cant you just put shrink on after you cut the wire, before you strip it? then slide it up and shrink it after the solder joint is finished. Ive done it a thousand times.
Also, I just hold two wires parallel, twist them, solder them; then solder the other wire directly to the two like a normal joint. Its faster, easier and will hold up just as well.\
Twisting wires isn’t actually necessary, if you make a good solder joint parallel wires will be just as durable.
Cheers
Ian
“why cant you just put shrink on after you cut the wire, before you strip it? then slide it up and shrink it after the solder joint is finished.”
Now I’m confused. This particular article is about tapping into a wire, which by definition is a wire that’s already connected on both of its ends. Yes, if you have one end of the wire free, it’s an easy matter of slipping the heatshrink on over the free end.
“Also, I just hold two wires parallel, twist them, solder them; then solder the other wire directly to the two like a normal joint.”
I’ve never heard of soldering on top of an existing solder joint. If this technique works for you, I’m glad to hear it. I prefer my method, because…
“Twisting wires isn’t actually necessary”
The primary application for the techniques in this series is motorcycle wiring. A motorcycle is a harsh environment, particularly in terms of vibration. Twisting the wires provides an extra mechanical connection in addition to the solder.
It takes less than one second to twist a pair of wires together. I’m fine with spending that extra second for some additional insurance.
{ 1 trackback }