crimping, interconnecting cables, harnesses, and wiring - NASA

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NASA-STD-8739.4 with Change 6
available in both an insulated and uninsulated version. The splice provides a very small diameter
profile when installed in a harness.
Figure 19-27. Butt Splice
19.14.1 Preparation. The conductor(s) shall be stripped per (par 10.1) and trimmed to length to
allow full insertion into the crimp barrel, such that the conductor ends are visible in the wire
inspection hole (Requirement).
19.14.2 Contact Sizing
a. Single Conductor Configurations. The butt splice contact shall be sized and selected
according to the conductor-crimp combinations listed in MIL-DTL-22520G [Table III], or as
specified by the crimp contact manufacturer (Requirement).
b. Multiple Conductor Configurations. For designs involving the crimping of multiple
conductors in one or both ends of the contact (see Figure 19-28), the equivalent wire size (EWS)
must be determined in order to select the appropriate contact size. To calculate EWS, the sum of
the circular mill area (CMA) of the wires to be spliced, multiplied by 1.25, shall determine the
equivalent wire size and the corresponding initial contact size (Requirement).
Figure 19-28. Butt Splice Prior to Wire Insertion
Figure 19-29. Butt Splice Prior to Crimp Figure 19-30. Properly Crimped Butt Splice
19.14.3 Assembly
a. The conductor(s) shall be fully inserted in the crimp barrel, parallel to each other, and without
modification to the conductor(s) or crimp barrel (see Figure 19-29) (Requirement).
b. Conductor insulation gap(s) should be approximately equal, but shall comply with the
insulation gap requirements specified in (par 10.1.7.b) for each conductor size (Requirement).