crimping, interconnecting cables, harnesses, and wiring - NASA

19. SPLICING
19.1 General
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NASA-STD-8739.4 with Change 6
Splices may be configured as a simple splice, having one conductor joined to another conductor,
or as a complex splice with one or more conductors joined to one or more other conductors.
Splices may be completed using crimping or soldering processes.
19.2 General Information
Unless identified as part of the design in the manufacturing/engineering documentation, splices
shall be considered repairs and shall be handled in accordance with paragraph 4.5.2
(Requirement).
19.2.1 Soldered splice terminations shall comply with NASA-STD-8739.3. Solder connections
shall be inspected prior to and after shrink tube heat application (Requirement).
19.2.2 All areas that will be under insulation sleeving shall be cleaned with an approved solvent
as defined by NASA-STD-8739.3 Table 6.1 (Requirement). Cleaning solution application shall
be controlled to minimize propagation to other areas of the harness or cable being spliced
(Requirement).
19.3 Design Considerations
The use of splices in a harness design should be minimized as much as possible. The simplest
and most reliable wiring design is one that results in the routing of a dedicated, continuous, and
unbroken conductor from point to point. The following shall be incorporated into any splice
design:
19.3.1 Shrink sleeving over the splice area shall be protected from cold flow and abrasion
(Requirement).
19.3.2 Splices shall be covered with a single layer of heat-shrinkable tubing or insulation
material that meets or exceeds the minimum electrical isolation specified in the engineering
documentation (Requirement). The tubing/insulation shall completely encapsulate the splice
body and extend over the wires’ insulation a minimum of two times (2X) the diameter of the
largest wire in the splice (Requirement). Additional layers of tubing/insulation may be added to
increase electrical isolation or to provide additional environmental or mechanical protection.
Each additional layer shall overlap the underlying layer by at least two (2) diameters of the
largest wire in the splice at each end (Requirement).
19.3.3 Splices shall be staggered to minimize buildup of the wire bundle diameter
(Requirement).
19.3.4 Splices shall not be located in areas of the cable where flexing may occur or in bend radii
where the primary insulation may be compromised (Requirement).
19.3.5 There shall be no splices within two harness diameters of a breakout (Requirement).
19.3.6 Splices, including location and type, shall be identified and fully defined on the
associated drawings (Requirement).