Some commenters on my post about using a washer as a soldering aid noticed my sloppy splicing technique and were kind enough to educate me about the so-called â€śWestern Union splice,â€ť aka the â€śLinemanâ€™s splice,â€ť which is the preferred method for twisting solid-core wire leads together for inline electrical connections.
Developed during the heydey of the telegraph, the Linemanâ€™s splice is designed for joining wires that will be under tension. It is commonly claimed that, properly made, a Linemanâ€™s splice is stronger than the wires of which it is composed. In any case, it is a time-proven method, and, coolest of all, one of NASAâ€™s Required Workmanship Standards. To wit, in a NASA-approved Linemanâ€™s splice:
- The conductors shall be pre-tinned.
- There shall be at least 3 turns around each conductor and the wraps shall be tight with no gaps between adjacent turns.
- The wraps shall not overlap and the ends of the wrap shall be trimmed flush prior to soldering to prevent protruding ends.
- Conductors shall not overlap the insulation of the other wire.
Though the Linemanâ€™s splice was originally used without solder, today soldering is common. And NASA insists on it:
- Solder shall wet all elements of the connection.
- The solder shall fillet between connection elements over the complete periphery
of the connection.
This material comes from page 84 of NASA-STD 8739.4 (PDF), which is a great reference if youâ€™re interested in best practices for interconnecting cables and wires.