Splicing Wire the NASA Way

[dacap06]

40 years ago as a freshman in college, I ran across the lineman's splice technique and promptly forgot about it. I just ran across it again, as NASA uses it as their standard for solid wire. With a bunch more EE experience under my belt I now appreciate the importance, simplicity, and beauty of it, although I can't use it professionally since IT cable work normally requires no splices at all due to the high frequency signals involved.

I just thought I'd share, thinking y'all might find it as useful for boat work if multistrand wire is not involved. Enjoy!

[pdqaltair]

Please correct me if I am wrong.

The linesman's splice is for solid wire only and nearly all marine wire is finely stranded. It would be impossible to execute properly with stranded wire. Yes, you can twist wires together, but you cannot form them to function as intended. If you read the referenced NASA quality document, the illustrations seem to make this clear. Certainly a good method for solid wire.

Thus, I believe this method is generally not applicable.

[Dubbinchris]

This is very similar to the manner in which I will splice stranded wire. Of course I can't make it coil up against itself like with solid wire but it's pretty close. After soldering it gets shrink tube over it.

[H and E]

I have been using that type of splice for years on stranded wire. If critical I solder it. Some I have just used electrical tape others shrink tube. I have some on the boat that are soldered with shrink tube. Now days I tend to use crimp connectors most of the time.

[Maine Sail]

No wire twisting of any kind eg: Western Union/Lineman's Splice etc. meets the minimum ABYC Electrical safety standards and counts as a "mechnical connection".

As has been accurately pointed out by NASA and others a WU splice is for solid wire, not the finely stranded wire we use on boats...

[pdqaltair]

I think the posters are missing a key point. Without the hard first turn and the rigidity of solid wire, this is NOT a mechanical connection. Done with solid wire, it is as strong as the wire. A crimp is as strong as the wire. In stranded wire, if this gets hot enough to melt the solder (fire or short), the wire will start to open up and it will fall apart. Stranded wire is not "pretty close" and not stay that way when it's hot, certainly not as the size goes up.

NASA did not show stranded wire, as they did in every other example. In the other hand, solid wire does not crimp well and it has less surface for solder, so this is the best method for solid wire.

Different horses for different courses, not another way to splice stranded wire.

[Silvio]

So,
What is the best practice then for splicing stranded wire?

[blutoyz]

So the general consensus here is that this is NOT the recommended method for saltwater connections with stranded wire?

Just want to be sure, I have lots of wiring to ring out on my "new" boat this spring.

[Maine Sail]

Originally Posted by Silvio

So,
What is the best practice then for splicing stranded wire?

A properly crimped butt splice made with the proper tools.. If you use factory made adhesive lined heat shrink butts they will be impervious to water. These same type of splices are used on millions of 240V artesian well pump motors. These adhesive lined butt splice crimps are used in a 100% submerged environment for 20+ years at a time...

[Barquito]

As has been accurately pointed out by NASA and others a WU splice is for solid wire, not the finely stranded wire we use on boats...

Begs the question: Why would NASA be using solid wires? Maybe this is just for ground based applications.

As a mental exercise, would the addition of a big blob of solder actually cause more fatigue at the transition between solder and wire with movement?