Three-way Wire Splicing
- Thread starter lBasket
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Variations of these seem to be increasingly common in home wiring (maybe commercial, but I have no idea there).
I feel pretty validated right now. I was not too eager to share that technique for fear of being pimpslapped my hackery.
KennethS
TJ Addict
I'd rather see it done that way that just trying to crimp down on a too small wire in the butt connector. Lest we forget, the double wire size isn't sealed very well but, better than not at all.
If you have a smaller size shrink wrap you can shrink A short piece down on the jacket to add some girth for the larger shrink wrap over top. It’ll be a little better seal.
It isn't a diameter issue, it is depending on the adhesive to flow between the two wires.
So,
Make lists when I find these
Step down I found but not these
Have the heat shrink adhesive water resistant
And the wire Loom with the strip a good tip
High temp engine bay electric tape cloth etc, is by far the #1, electric tape is NOT all the same, sticky nasty mess after 40 miles.
Learned the lesson “If you don’t find the time to do it right the first time, you’ll find the time to do it right the second time when it fails”
Spent 4 hours rewriting a buddies lights after learning this in this site, he thought I was crazy, and 3 years out all his intermittent fog and KC lights “magically” finally stopped ha. He now admits Magic is details ha.
@mrblaine got me started on non-insulated butt connectors and adhesive shrink tubing with a tool that has a stake crimp. Now I’m addicted. I could go for hours. It’s very satisfying.
So, there's another way to do this, use a uninsulated butt connector that fits two wires in one side, and strip double length of the third wire, fold it over so its double sized, and stick it in the other side. Then double heat shrink, smaller on single wire side, then larger over the entire thing.
I wish me and Hear would have thought of doing it that way.
Pictures help some folks understand the nuance. These are both marked 3/16" 3-1 ratio
The consequence of that big difference happens when you use it on smaller wires that still should be within the rated shrunk size.
Below is 1/4" 4-1, 1/4" 3-1, 3/16" 3-1, and 1/8" 3-1
When you shrink them onto the same splices, the larger 3/16 3-1 doesn't shrink far enough to reliably squeeze the melted adhesive out the end to show it works as it should.
1/4" 4-1 with the adhesive pushed out, 3/16" that almost got it done, and then the 1/8" with lots of visible adhesive.
Not that it will matter for most connections but if you are splicing multiples and need to keep the bundle as small as possible to fit into your loom size, you can see the oversize 3/16" winds up with a large wall thickness after shrinking even compared to the larger 1/4". This is another reason I use the Wirefy stuff, it is listed as a dual wall, but it is the thinnest dual wall adhesive lined I've been able to find. Doesn't mean I think the Wirefy is the best, it is just the thinnest I've found.
The consequence of that big difference happens when you use it on smaller wires that still should be within the rated shrunk size.
Below is 1/4" 4-1, 1/4" 3-1, 3/16" 3-1, and 1/8" 3-1
When you shrink them onto the same splices, the larger 3/16 3-1 doesn't shrink far enough to reliably squeeze the melted adhesive out the end to show it works as it should.
1/4" 4-1 with the adhesive pushed out, 3/16" that almost got it done, and then the 1/8" with lots of visible adhesive.
Not that it will matter for most connections but if you are splicing multiples and need to keep the bundle as small as possible to fit into your loom size, you can see the oversize 3/16" winds up with a large wall thickness after shrinking even compared to the larger 1/4". This is another reason I use the Wirefy stuff, it is listed as a dual wall, but it is the thinnest dual wall adhesive lined I've been able to find. Doesn't mean I think the Wirefy is the best, it is just the thinnest I've found.
Exactly. I'm always worried about that "crotch" that is created on a 3 way splice. I've even dabbed a bit of RTV in there "just in case" in addition to using the meltable inner wall heat shrink.
I found a few more pieces to mess with. When we started, all we could readily get was the 3M stuff from Del City and they didn't have 3/16" at that time, you got 1/4" and 1/8" so we wound up using a lot of 1/4" 3-1 on small connections. It made for a very bulky connection. Later we were able to source the more appropriate 3/16" that is on the end to show the difference.
This was alot of good info. I've never thought that much about this stuff.
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