View source for Engineering:Western Union splice

{{Short description|Method of joining electrical cable}}
[[File:Western Union splice.jpg|thumb|Figure parts A–D show steps in forming a "short tie" Western Union splice. Figure parts E and F show two possible "long tie" variations. {{refn|Taken from Figures 1 and 2 of <ref name="JMSharp_pp13f">{{cite book |last=Sharp |first=John MacLaren |year=1915 |title=Practical Electric Wiring |publisher=D. Appleton and Company |location=New York and London |url=https://babel.hathitrust.org/cgi/pt?id=wu.89089723613&view=1up&seq=27 |pages=12–14}}</ref> and re-labelled.}}]]

The '''Western Union splice''' or '''Lineman splice''' is a method of joining [[Engineering:Electrical cable|electrical cable]], developed in the nineteenth century during the introduction of the telegraph and named for the [[Company:Western Union#History|Western Union]] telegraph company.<ref>{{cite web |last=Lemau |date=2010-09-26 |title=Conductor splices |website=Electrical Engineering Centre |lang=en-US |url=https://www.electricneutron.com/wiring-techniques/conductor-splices/ |access-date=2020-01-22}}</ref><ref name=":0" /> This method can be used where the cable may be subject to [[Structural load|loading stress]]. The wrapping pattern design causes the join to tighten as the conductors pull against each other.<ref name="NASA">{{cite web|url=http://workmanship.nasa.gov/guidadv_recmeth_wusplice.jsp|title=Western Union/Lineman Splice|publisher=NASA Workmanship Technical Committee|url-status=dead|archive-url=https://web.archive.org/web/20090801165108/http://workmanship.nasa.gov/guidadv_recmeth_wusplice.jsp|archive-date=August 1, 2009}}</ref>

== History ==
In 1915, ''Practical electric wiring'' described it as being, "by far the most widely used splice" in practical electrical wiring work.<ref name="JMSharp_pp13f" /> NASA included the splice in its technical standard ''Workmanship Standard For Crimping, Interconnecting Cables, Harnesses, And Wiring'', first produced in 1998.<ref>{{Cite web|url=https://nepp.nasa.gov/files/27631/NSTD87394A.pdf|title=Workmanship Standard For Crimping, Interconnecting Cables, Harnesses, And Wiring|year=2016|publisher=NASA|page=71|orig-year=1998}}</ref><ref name=":0">{{Cite web|url=https://makezine.com/2012/02/28/how-to-splice-wire-to-nasa-standards/|title=How-To: Splice Wire to NASA Standards {{!}} Make|date=2012-02-28|website=Make: DIY Projects and Ideas for Makers|language=en|access-date=2020-01-22}}</ref> 

== Construction ==
The 1915 textbook ''Practical Electric Wiring'' describes the construction of the Western Union splice; short tie and long tie. The short tie splice has it being formed after [[Engineering:Wire stripper|stripping the insulation]] from a pair of wires for several inches, each, crossing the wires left over right as shown in figure part A; then, a hooked cross (figure part B) is formed holding the crossing point of the two wires, and pulling the right wire tip toward and pushing the left wire tip away from the worker, leaving the tips oriented vertically as shown.<ref name="JMSharp_pp13f" /> The wires are then held with [[Engineering:Pliers|pliers]] to the left of their crossing point while the right splice is formed by continuing to wind the wire tip away from the worker, creating 5–6 twists snug against the core wire and against each preceding twist.<ref name="JMSharp_pp13f" /> NASA recommend "tight, with no gaps between adjacent turns".<ref name="NASA" /> The wires are then again held with [[Engineering:Pliers|pliers]], but on the first-made twist, to the right of the crossing point, and then the left splice is formed by winding the remaining wire tip toward the worker for a comparable 5–6 snug twists.<ref name="JMSharp_pp13f" /><!--Use of the word "counterclockwise" would have required a complicated description of a reference viewing direction, which if axial along the wire could have been clockwise or counterclockwise, depending on which wind of the slice was chosen. It was simpler to describe the process **as it was given in the 1915 source**, which does not use either clockwise reference at all.--> The splice wire ends are then trimmed as needed, and the splice may then be soldered, and/or covered (e.g., with a [[Engineering:Heat-shrink tubing|heat-shrunk tube]] of insulation).<ref name="NASA" />

''Practical Electric Wiring'' described the splice as having two variations, the "short tie" (figure part D) and "long tie" (figure parts E or F), with the latter examples having a "twist between wrappings [that] allows a better chance for [[Chemistry:Solder|solder]] to pass in between the wires". The book suggested the long tie variant more suited to splices where soldering was intended. However, this was not backed up by NASA testing.<ref name="JMSharp_pp13f" />{{r|nasalink}}

===Testing===

The NASA tests included soldering, and were performed to an organizational [[Medicine:Standard operating procedure|standard operating procedure]] (NASA-STD-8739.3) for a solder termination, which includes a number of specific requirements, including "proper insulation spacing"; tight wrapping; trimming of wire ends to prevent protrusions through the solder; and over-sleeving with a transparent or translucent heat shrink seal to cover the completed splice and all exposed metal.{{r|nasalink}}

NASA found both the short and long tie variants to be strong when soldered. The splices were examined in [[Physics:Tensile strength|tensile strength]] ("pull") tests on 16 and 22 [[American wire gauge]] wire; even the short tie variation of the Western Union splice performed well after soldering. The test splices never failed at the splice (instead breaking outside of the splice area), leaving NASA to conclude that "the solder connection at the splice was as strong or stronger than the un-spliced wires".<ref name="NASA" /><ref name=nasalink>{{Cite web|url=https://nepp.nasa.gov/index.cfm/5544|title=Links To Required Workmanship Standards - NASA interconnection standards (including NASA-STD-8739.4)|publisher=NASA|website=nepp.nasa.gov|access-date=2020-01-22}}</ref>

== See also ==
* [[Engineering:T-splice|T-splice]]
* [[Engineering:Rat-tail splice|Rat-tail splice]]

== References ==
{{Include-NASA}}
{{reflist}}


[[Category:Telecommunications equipment]]
[[Category:Electrical wiring]]

{{Sourceattribution|Western Union splice}}