How to Solder a Spliced Joint to NASA Specifications
This material comes from NASA-STD 8739.4, which is a great reference if you’re interested in best practices for interconnecting cables and wires.
This splice is known as the “Western Union splice”, or the “Lineman’s splice” and is the preferred method for twisting solid-core wire leads together for inline electrical connections.
Developed during the heyday of the telegraph, the Lineman’s splice is designed for connections that will be under tension. It is commonly claimed that, properly made, a Lineman’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 NASA’s Required Workmanship Standards. To wit, in a NASA-approved Lineman’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.