crimping, interconnecting cables, harnesses, and wiring - NASA

Page 87 of 114
NASA-STD-8739.4 with Change 6
termination (Requirement). Splices using the crimp ferrule method may be of the end-type or
parallel type. End type splices (see Figure 19-25) are used to terminate two or more conductors
in a “pig-tail” configuration, and to “dead-end” a single conductor. Parallel splices (see Figure
19-26) are used to dress and terminate multiple conductors, of the same or different gauges, in a
parallel configuration.
Figure 19-25. End Type Splice Figure 19-26. Parallel Type Splice
19.13.1 Preparation. The splice is accomplished using a crimp ferrule. The type of crimp barrel
to be used should be specified on the engineering documentation. For nickel-plated wire, or
silver plated wire in applications above 150º C, the nickel-plated crimp barrel is recommended.
Determine the size of the crimp barrel based on the manufacturer’s specifications.
a. For the end type splice the wires being spliced shall be inserted into the barrel parallel to each
other and all wires shall be seated against the bottom of the barrel (Requirement).
b. For the parallel type splice the wires shall be inserted into the ferrule parallel to each other
(Requirement). The wire ends shall be at least flush with the ends of the ferrule and shall not
extend more than two wire diameters beyond the end of the ferrule (Requirement). Proper
insulation spacing shall be maintained to prevent insulation from being crimped (Requirement).
19.13.2 Crimping. Use the crimping tool identified in the engineering documentation or the
crimp ferrule’s data sheet. Crimp and inspect per manufacturers instructions. The contact shall
be deformed only by tool indenters (Requirement). Indents shall be symmetrical and centered on
the crimp barrel (Requirement). There shall be no exposed base metal or other damage
(Requirement).
NOTE: This type of crimped connection will typically be installed with
a crimp tool with 2 indenter blades instead of the normal 4
indenter blades.
19.14 Butt Splice
The butt splice (see Figure 19-27) is one of the simplest and most often used of the crimp splices,
and obtains its name from the alignment of the conductors in the crimp barrel. The crimp is