ELECTRICAL MAINTENANCE PRACTICES
3-1. Installation Inspection of Wires and Cables.
Installation inspection of wires, cables, and their
components is explained in the following paragraphs.
Refer to TM 55-1500-323-24 for wire maintenance
Inspection Requirements. Wires and cables
shall be inspected for adequacy of support, protection,
and general condition throughout. The desirable and
undesirable features in aircraft wiring are outlined below
and indicated as conditions that should or should not
exist. Inspect aircraft wiring as follows:
Ensure wires and cables are supported by
cushion clamps, grommets, or other approved devices,
at intervals of not more than 24 inches, except when
contained in troughs, ducts, or conduits. The supporting
devices must be of a suitable size and type, and the
wires and cables must be held securely in place without
damage to the insulation.
Provide adequate stand-off support where
wires are routed over any structural member in such a
manner that chafing is likely to occur. Ensure that the
use of proper insulating material, is wrapped over wire
or cable to protect against chafing, is not being used in
applications where stand-off supports could be installed.
Ensure phenolic blocks, plastic liners, or
rubber grommets are installed in holes in bulkheads,
floors, or structural members through which wiring must
pass and it is impossible to install off-angle clamps to
maintain wiring in a fixed position away from edges of
holes. In such cases, additional protection, in the form
of plastic tubing or insulating tape is optional.
Ensure wires and cables in junction
boxes, panels, and bundles are properly supported and
laced to provide proper grouping and routing.
Make sure any retaining screw or
bulkheads, panels, etc. , does not
Ensure clamps and retaining screws are
properly mounted and secured so that any movement of
wires and cables is restricted to the span between points
of support. Movement of wires and cables should not
be transmitted to soldered or mechanical connections
such as terminal posts or connectors.
supported and bound so that interference with other
wires, cables and equipment does not exist.
adequately supported to prevent excessive movement
in areas of high vibration.
Ensure insulating tubing and tape is
secured in place by tying or with clamps.
Ensure continuous lacing is not used,
except in panels and junction boxes where this practice
is optional. Lacing installed in this manner outside
junction boxes shall be removed and replaced with
Ensure that tapes (such as friction tape)
which will dry out in service, produce chemical reactions
with wire or cable insulation, or absorb moisture, are not
Ensure minimum use of insulating tubing
is made when used to protect wire and cable from
abrasion, chafing, exposure to fluids, and other
conditions which could affect cable insulation. Use of
insulating tubing for support of wires and cables
Do not use moisture-absorbent material
as fill for clamps or adapters.
Check that wires and cables are not tied
or fastened together in conduit or insulating tubing.
Check that cable supports do not restrict
the wires or cables in such a manner as to interfere with
operation of equipment shock mounts.