Dr-Fix-It! Notebook Archive:
Twisting a Joint . . .
You probably think nothing of making an electrical connection. Simply bring two wires together, give them a quick twist and then screw a wire-nut on the exposed wire. A few more twists of the wire-nut and the connection is made. Oh, you might want to wrap a little electrician's vinyl tape around the base of the wire-nut for extra safety but that is all there is to it. In almost no time at all, you have made a safe and highly efficient wire connection with a minimum of technical expertise. But such simplicity has not always been the case.
Believe it or nut, the wire-nut is not even as old as the airplane. Credit for the invention of the wire-nut is generally given to William Marr who patented a "pressure type wire connector" in 1914. Marr introduced the new connector under the trade name "Marrette" and millions are still sold daily by that name.
But, back in the days of the Wild West, there was a desperate need to make solid, efficient electrical connections quickly and inexpensively. Through sheer necessity, Western Union Telegraph company pioneered research and development of making wire connections. To complete the ambitious task of building the first transcontinental telegraph line, Western Union engineers launched a Research and Developement Project aimed at gaining more knowledge of the simple wire splice.
The oldest telegraph splice - the original mainstay of telegraph wire connections is known, appropriately enough, as the Western Union joint. 'Cold' (that is; not soldered - just twisted together), it is about 65 percent efficient and retains about 55 percent of the strength of the wire. Soldered, it becomes over 95 percent efficient.
The Western Union joint is made by grasping two opposing wires at a midpoint about four inches from the ends. The loose end of one wire is wrapped around the other wire at least five revolutions - ten revolutions is preferred. The operation is duplicated with the other loose end. A firm snap of the wires pulls the joint tight. Then the loose ends are trimmed flush.
I can't find any historical reference so I can only assume that a certain Mr. McIntire invented the 'McIntire joint'. Because the McIntire joint was more efficient, stronger and vastly simpler to make, The Western Union Telegraph Company adopted its use in place of the 'Western Union joint' on the transcontinental telegraph line.
Just twist two wires together - - - You probably have been making McIntire joints for years and didn't know there was a name for them. The McIntire joint is made by grasping two opposing wires at a midpoint about two inches from the ends and wrapping each end around the wire at least four revolutions. Cold, the McIntire joint ranks as about 70 percent efficient and retains about 75 percent of the strength of the wire. Soldered, it also becomes over 95 percent efficient.
Western Union completed the transcontinental telegraph line on October 24, 1861. Some 53 years later, the technology of wire connections surged ahead with the advent of the wire-nut. For the first time, it was possible for untrained personnel to consistently make strong wire connections that exceeded 90 percent efficiency.
But, even in this modern era, there is room for Civil - War - Era technology. Seven score and four years after the transcontinental telegraph line, it sometimes comes in very handy to know how to make the Western Union joint. It's great for speaker wire connections and perfect for under-the-dash wiring because it won't pull apart and is highly resistant to vibration fatigue.
Friends who are in the business of 'pulling' data / com wires live by the rule that computer intranet cabling must be clean and pure with absolutely NO splices. ( PSSSST . . . Don't tell anybody but, in a more than one 'emergency' situation, I have successfully used the Western Union joint on cat-5 ethernet connections and noticed no degradation of data or transfer speed! )
So, take a few seconds to learn a couple of old telegraph splices. You can help preserve a bit of electrical history that dates back to the days of the Wild West. Best of all, these techniques are still useful today. After all, you never can tell when you might need to twist up a joint.