MIL-DTL-917F(SH)
3.12.2.1.3 Flexible wiring. Where flexible wiring is required by hinged doors, panels, or sliding
subassemblies, abrasion and chafing shall be minimized by the use of flexible plastic sheaths on wiring. Wire
groups running from hinged panels or doors shall be formed and clamped so that sharp bends do not occur with the
panel or door in either the open or closed position; and, if more than three wires are contained in the group and the
panel or door is required to be removable, a terminal block (or the receptacle portion of a multi-pin connector,
where permitted) mounted on a stationary part of the structure within the enclosure or on the hinged panel or door
shall be used for connections. Flexible harnesses shall be broken down into individual bundles.
3.12.2.2 Slack. Slack shall be provided so as not to impair movement or put undue stresses on the wires or
parts in those places where movement of parts may be expected. Slack shall also be provided to prevent undue
stresses on terminal connections due to shock or vibration. Where soldering is used to connect hook-up wires to the
terminals of replaceable parts, sufficient slack shall be provided for at least two replacements of the part in the event
that the wires are damaged or have to be clipped at the terminals during disassembly. Where solderless lug
terminals are used, sufficient slack shall be provided for two replacements of the terminals on 14 AWG and smaller
wires.
3.12.2.3 Mechanical supports. Electrical connections shall be designed and provided with supports to prevent
breakage and minimize changes in performance due to vibration, inclination, or shock.
3.12.2.3.1 Clamped connections. Where electrical connections are constructed of members in firm contact,
such as parts held together by bolts, the contacts shall not depend on force transmitted through plastic spacers or
other deformable parts. Only metal parts shall be so employed and these electrical connections shall not rely on the
clamping screw, bolt, or fastener threads to carry current. However, stud type semiconductor devices may be
mounted separated from their heat sinks or other mounting surfaces by insulators when direct metallic contact is
incompatible with the circuit requirements, provided the method of mounting conforms to the device manufacturer's
recommendations.
3.12.2.4 External cable connections. Provision shall be made for the connection of external cables to terminal
boards located within the equipment near the cable entrance, except where individual equipment specifications
permit or specify some other methods, such as direct connection to parts, connections using wire nuts, or multi-pin
plug connectors (see 6.2). All terminal boards for external connections shall be accessible from the front of the
enclosure. Circuitous routing of wire shall be avoided.
3.12.2.5 Protection of insulation. Where equipment internal wiring is run through holes in metal partitions,
these holes shall be furnished with grommets for the mechanical protection of insulation which otherwise could be
subject to abrasion. Care shall be exercised in the running of wires to ensure they are not carried over or bent
around any sharp corner or edge. In radio frequency (RF) circuits, the grommets shall be ceramic or
polytetrafluoroethylene.
3.12.2.6 Shielded wire. Wire having metallic shielding unprotected by an outer insulation shall be so secured
as to prevent the shielding from making contact with exposed terminals or conductors. The shielding shall be
terminated as close to the circuit terminals as possible without risk of grounding the terminals. Where grounding of
the shielding is required by the circuit design, the ground connection to the chassis shall be made by means of
terminal lugs, screw type terminals, or bolts.
3.12.2.7 Stud terminals. Stud terminals of potted parts shall be fastened to the insulating strip or plate or the
enclosure itself to conform to the insulation requirements. The soldering of external leads to the stud terminals shall
not cause any degradation in the moisture excluding property of the enclosures.
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