Master a perfect inline wire splice everytime

Picture of Master a perfect inline wire splice everytime
In this instructable i will teach you how to make a perfect inline wire splice, every time

What is an inline splice?

Well, if you work with any type of electrical wiring, and need to join 2 pieces of wire you have 2 choices, pigtail or inline

Pigtail splices are when you hold the 2 pieces of wire, one end going up, the other going down, and twist their stripped ends together.

The issue with pigtails are...

1) They are ugly

2) They redirect the wire 180 degrees, so going from point A to B requires a sharp bend

3) After making that sharp bend you have this chunk of pigtailed wire flopping about, usually with a nice wad of gooey black tape, and sometimes a zip tie to act as a strain control

4) Since the connection is 180 degrees (or going the totally opposite direction) without some form of strain control, all it takes is a stout yank to sheer the connection (even with solder), altho honestly this is an extreme con

The pro's of pigtail's are
1) they are "easy"

Inline splices is where you take two pieces of wire, and join them in a nearly seamless extension of wire

Inline the issues with inline splices are ...
1) the are "hard" (and I claim shenanigans!)

The pro's of inline splices are
1) They are almost invisible, and look professional

2) They do not redirect the wires natural flow, going from point A to point B is just as simple as if you had the chance to place a wire from point A to point B

3) Since there is no bends in the wire, there is no chunks to manage, which is especially handy in tight situations or where you do not have a lot of wire to waste (ie: repairing wires in a vehicle)

4) they are really strong, even without solder bonding them (keeping in mind that they are not permanent, stress and vibration will eventually disconnect them without solder)

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Step 1: Supplies

Picture of Supplies
Something to splice
1 thumb and 1 finger per hand
Hemostats or needle nose pliers and maybe some gloves (see below)
Wire stripping utensil
Soldering Iron
Insulating material (heat shrink tubing recommended)

let me go off on a green note for a moment, my wire was scavenged from an old computer power supply, if you see anyone throwing away an old pc, snag it, its LOADED with wire thats good for jumper wires on your veroboard , or ribbon cable witch is also good for jumping, but since its tiny it works well with smd devices ect ...

your standard "still working but junk" power supply will net you a fiist full of wire, some voltage regulators, a heat sink, at least 1 good fan, a couple big caps, some other random electronic components, a handful of molex connectors for fans, or a nice +- 5v, +-12v and 3.3 volt bench power supply that can handle 10+ amps!

scrap the motherboard and you end up with MORE voltage regulators, connectors and swag, and if the case is at least ATX, well there you have a perfect platform for your pimping case mods, all for the cost of stopping the diptards at work from tossing that Pentium II thats been in the closet for over a decade, which equates to "hey let me have that!", as its headed to the dumpster

OK, about the hemostats and or needle nose pliers. you can do this technique with any gage wire, solid or stranded, but a brief word of warning!

even small gage solid core wire has a habit of screwing your hands up, ive had 24 gage stuff go deep into my thumb with little effort, and one time it went in to my thumb, to the side of my bone and thumbnail, and poke out the other end quite a bit (felt like a paper cut, until i pulled it out)

same with thick stranded wire, get some thick stranded wire and those strands become stray needles

if your working with these types of wire, pigtailed or inline, i recommend the use of metallic objects when you get to a point where twisting the wire

You should be able to start, and nearly finish the twist with your hands, but once it gets tough for your fingers, go for the tools, rather than a gash / piercing, and some nasty words spoken out loud around your loved ones

In this instructable I was using 20 gage stranded wire, which is quite soft, and wont poke my tough old work fingers at all

Step 2: Stripping your wire

Picture of Stripping your wire
One of the major keys to making a perfect inline splice is stripping your wire to about the same length on both ends

In a perfect world it would be exactly the same length

In my world its regulated down to the Centimeter marking i drew out with a sharpie on my work surface, based on a hot pink ruler i got tired of looking for

I aimed to strip 2cm off the insulation, as long as its pretty even you should be just fine, you could even eyeball it (and most of the time i do)

my stripping utensil of choice tonight was a hobby knife / xacto / scalpel, I like these when dealing with stranded wire in a workbench situation, but you can accidentally cut it clean off when using thin wire, and with thin solid core wire you really risk the chance of nicking the wire, once that happens it will break clean off, so use whatever suits you best for whatever application (same applies for "automatic strippers")

Step 3: Starting the splice

Picture of Starting the splice
Now that your wires are stripped to basically the same length. you need to cross them in a X form, where the center of the x is about midpoint of the 2 stripped sections of wire

Step 4: Start of the splice

Picture of Start of the splice
Whichever wire is on top (closest to you) bend away (or back) and then down, the wire will make a upside down L shape around the back wire

Step 5: Start of the splice part two

Picture of Start of the splice part two
Now take the other wire, bend it towards you (or forward) and then down, twisting it around the first wire, making a M shape

Step 6: Continue twisting

Picture of Continue twisting
There are two directions to twist, you do not want to twist the entire wire, just the splice.

I recommend using your thumb and forefinger of each hand, 1 will go clockwise (or towards you) the other will go counter clockwise (or away from you), pinching hard, twisting only the spliced section, slowly moving towards the insulation with both hands

if your using solid core wire, or thick gage wire once you get near the ends I strongly recommend you wear gloves or use hemostats / needle nose pliers to finish up the twist

if you got close enough to the same length of stripped wire, and made your X close enough to the center of the 2 wires you should end up with both ends of the wire running out just at, or before the start of the insulation

And a super strong splice ready for service

Step 7: Wrapping up

Picture of Wrapping up
Solder the splice, but be warned once its soldered properly its quite a struggle to get it back apart, its actually easier to cut the splice out and start over, so make sure you have your heat shrink and whatever other accessories (ie parts to a fuse holder) in place before

Once you have done this a few times, it will become just as fast, as a simple pigtail

Your electronics enabled buddies will nod to you, and your other friends will be amazed at the clean nearly invisible splice, and how fast you managed to do it

Thanks for your time, and please if you have any questions or comments post them

-- Osgeld

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kewrw2811 hours ago

Nice job. I will use this on my next soldering project, THANKS

Aarushk13 days ago

really helpful!

clazman17 days ago

A good example of the pigtail splice in use is a picture contained in the instructable:


clazman17 days ago

Very good description of an age old procedure.

You don't mention twisting the strands prior to. I have found that the splice can be slightly smaller. The downside is the the end of each wire can protrude from the intended splice "envelope". Still pre-twisting the wire is probably better.

I like to twist the insulation as I remove it. It does a nice job twisting the strands.

Why not use the iron to shrink the tubing rather than adding another "tool"?

If the heat shrink is slipped over the joint while it is still quite warm some shrinkage can occur.

Nice instructable!

nvahalik made it!1 month ago

Worked great!

bigbigdave6 months ago

Nice tutorial! Thanks!

I just used it on a project and discovered one shortcut that may help some folks: I had several wires already stripped before realizing I wanted to go this route and looked up this instructable, so the strips were slightly different lengths. If you line up the two wires like you're going to use the "pigtail" approach and with their insulation lined up (just like the pigtail picture in the intro), you can then snip both the ends off at the same time and make them EXACTLY the same length. Then just continue from Step 3.

lol i hope youre just bein a smartass cuz if not u may need to go back and redo 2nd grade

PeterC29 months ago

Thanks for this information I used it last evening and the joints look pretty cool and I can feel a lot more confident about them. Cheers

Thanks for the well-explained wire splice. Just what I needed to fix an on-demand hot water heater.

peterlonz2 years ago
This is well executed work & the instructions are clear.
Love the pros & cons section.
Why have you not mentioned the alternative simple solderless solution of using a screw down in line connector. Each wire can be gripped by two screws & there is probably no need to make the twisted splice. Please comment.
yarrow2 years ago
First off, great info and thanks for sharing! I have a question regarding soldering and the heat shrink...I work with a lot of weather equipment, generally located in the middle of agricultural fields and battery powered, and often have to make quick repairs thanks to mice, deer, and other charming wildlife chewing through various wires. Could a splice like this be done without soldering, and with just electrical tape in place of heat shrink? I realize it would be less than ideal, but field conditions are rarely ideal.
Unsoldered connections in the field will often (tempted to say always) become intermittent, unless they are made with a professional ($$$) crimping tool. Solder is foolproof and cheap. A good cordless iron will help you solder perfect joints in the field. Butane fired irons will shrink your HST after you solder your connection. I prefer soldering with a good cordless electric and using a cheapo mini-torch (or lighter, or match) for shrinking HST. Soldering will insure your repair doesn't become intermittent after exposure to humidity allows corrosion to begin.
This method of splicing has been around for many years, and is known as a Western Union splice.


As for lap soldering....yes, it works. But as the experts say, solder is not designed to make a mechanical connection - only an electrical one. Wires should be mechanically secured before soldering. A lap solder joint should not be used for heavy duty connections or heavy-duty use.
osgeld (author)  Jon Chandler5 years ago
we have discussed this in other comments WU splice is generally accepeted around here as being |||x||| and this is more like xxxxxxx googling the term western union splice turns up both, but the first one more often :)
pfred2 osgeld3 years ago
A Western Union splice is more like ---|||xxx|||--- so it is like the joint you are showing, but on each end the wire is wrapped 3 times around the other wire. Either that or my Radio Shack Dictionary of Electronics is wrong.
rfxcasey5 years ago
Just wondering what is wrong with simple lap soldering? When don't right they are very strong and quick to produce.
pfred2 rfxcasey3 years ago
If for some strange reason your wire heats up so much the solder melts your joint could come apart without a mechanical connection to keep it together. Then there is the issue that in order to do a lap joint you might have to hold 2 wires, a soldering iron, and solder, which is more hands than most of us have. But I do lap joints myself.
DeadlyDad5 years ago
FYI, if you use heatshrink tubing that contains an adhesive, then using this method will yield a neat and waterproof join.
CKOD DeadlyDad4 years ago
+1 to that, adhesive lined heatshrink is pretty much the best stuff ever.
pfred2 CKOD3 years ago
Until you want to take it off.
pfred23 years ago
Only every time you have enough wire to do it that is.
siafulinux3 years ago
Nicely done! Thanks.
My friends used have me wire thier amp because i never burnt one up simply because i insulated the wires and sldered where necessary these joints as i like call them twist up like a boobie lets call them wire joints western u8nion is so yesterday and RCA what have they done for me lately
This is "yesterday" technology. "Western union" describes the method rather than the splice itself. "Wire joints" sound vaguely "chronic".
cpo3 years ago
I love the "Your electronics enabled buddies will nod to you" bit!

I'm always using the "pigtail" connedction when wiring most things as it's easier to work with. I just overcome the "ugly" insulation by folding the connection over after soldering, and taping the connection to part of it's own length of wire. In fact, (seeing i hate working with heatshrink) i find taping "inline" connections more messy and prone to tape "sliding" along the wire and exposing the connection. It's just personal preference i guess, and when you're doing it all the time, you will develop your own quick method
Also, when soldering in line, or even in general, if you've got time, it does help to "tin" the ends and just solder them together rather than twisting them - as that degrades the integrity of the actual wire. It's good for proper professional connections - if you ever find yourself in such a situation.
qwertyboy5 years ago
Thank you so much for posting this. I was tired of all my connections coming apart easily and looking bad. With this method, the results look professional. In the photo, I had to add a LED inline with a fan to indicate when it was on. If I had tried to pigtail it, the results would have been bad. ~thanks~
TANZMEISTER5 years ago
Great information in the instructable! It might be helpful to add any notes about the soldering itself. Is soldering this splice any different then any other splice? A link that might be helpful to add, http://www.instructables.com/id/How-to-solder/ thanks for the great work!
arcnemisis5 years ago
Personally the improvements that this can make in a install or project far outweigh the time consuming part. Sure the pigtail/wire nut/soldered/twisted joint is easy, but it looks bad. I have been doing these joints (WU and just inline wrap RCA) for years while others wimped out. I try to spread the word and show them. Good job showing others how to do it right and make some projects cleaner and less tape gooeyness to go around.
chndt20085 years ago
richardcole5 years ago
nice trick and i think clean work is totally awesome... own heart satisfy when work to be done very well..
Pyro6675 years ago
hey thanks for making me feel like an idiot, J/K...well a little, I much cleaner than my usual method Thanks
This is great! I've done my share of electrical repairs over the years, and I've ALWAYS pigtailed. This seems like simple, common sense but it's hard to let go of habits. I did this once purely because I didn't have a wire nut and remember thinking how much more sense it made, but once properly supplied I went right back to pt without even thinking about it! Beats the hell out of those cheap inline "bullet" style connectors especially!
ssnipe5 years ago
From my experience: or you can use a "ENVIRONMENTAL BUTT SPLICE" its what we use in the aviation field works very well and weather proof might cost a bit more but a good investment. (quick google and might find a site like ...http://www.edmo.com/index.php?module=products&func=display&prod_id=18887 ... never bought or delt with them but its what im talking about)
sabr6865 years ago
Nice,thanks. I didn't know there was a name for this method. I just instinctively used this method to save on wire and tape!
steviebob5 years ago
Useful tutorial. Thanks.
V-Man7375 years ago
So simple! Everyone needs to know this. Thank you for sharing!
I have been searching for days now, and came upon this in a google search. I am hoping you could help solve this issue: I'm trying to redesign my home stereo system so that I can mount my new speakers. My problem is that I don't have enough inputs, so I am splicing a few wires here and there to make what is basically a patch panel for all my stuff. Normally, this isnt a problem for me, but it became one when I went to splice some of my spare cables, and realized some of them had 2 wires inside, and some had three... And no matter which way I would join them to their own kinds, somewhere along the line I would need to join some 2-wire to some 3-wire... Anyone got advice on this? The 2-wire ones have the inner coated wire surrounded by the first wire, and the 3-wire ones are just 3 separately coated wires covered by the outer coat... Any help would be greatly appreciated!
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