Keep Wires Locked Together With The Linesman Splice

Wire splicing and soldering is a basic skill that any DIY enthusiast can master — but it all starts with a solid connection between the two wires. That’s where the Linesman splice comes in.

Connecting two wires can be done with a wire stripper and electrical tape, but to make a proper connection you should solder them together, or at least use wire nuts. Wire nuts are screwed clockwise over the end of a pigtail splice or twist and fold as shown in the video above. Wire nuts connect and protect the wires, but often times you will need an inline splicing technique that doesn’t change the diameter of the wire.

The Linesman splice or Western Union splice (it was developed during the introduction of the telegraph) is an inline wire connecting technique that binds two wires together in such a way that if the wires are pulled apart, the connection will tighten.

Jump to :58 in the video above to see how Linesman splice is done. According to Make, this splice is the preferred connection method of NASA. Here’s how they suggest doing it (referenced from page 84 of NASA-STD 8739.4):

  1. The conductors shall be pre-tinned.
  2. There shall be at least three turns around each conductor and the wraps shall be tight with no gaps between adjacent turns.
  3. The wraps shall not overlap and the ends of the wrap shall be trimmed flush prior to soldering to prevent protruding ends.
  4. Conductors shall not overlap the insulation of the other wire.

Enjoy your stronger and space-ready connections.

How to Twist Wires for Soldering [Wire Barn — YouTube]


  • The end product is a great way to provide a high resistant joint if the cable has any sort of movement and solder is not encasing all the joint. A very poor joint even with it soldered.

    The second way is the better type of joint if running the maximum current through the cable.
    Surprised NASA allow any joint within a cable, full stop.

  • The modified linesman splice in that video is nothing like the one in the NASA documentation. As @swimwiz says, the version in the video will give high resistance – very poor way to join wires. The actual version in the NASA documentation is a very good way of doing it.

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