Table 2-2.-Wiring Circuit Function Code
point. Stamp wires which are 3 to 7 inches long
in the center. You don't need to stamp wires less
than 3 inches long.
Wiring and Cable Identification Codes
To make maintenance easier, each of the
connecting wires in an aircraft have an identi-
fication. The identification is a combination of
letters and numbers. The marking also identifies
the circuit it belongs to, gauge size, and other
information relating the wire to a wiring diagram.
This marking is the cable identification code. The
accompanying discussion explains the code used
in aircraft wiring. You can find complete details
in the Military Specification: Wiring, Aerospace
Vehicle, MIL-W-5088.
NOTE: Stranded conductor wire is used for
flexibility in installation and service. Wire sizes
approximate American Wire Gage (AWG). How-
ever, they vary sufficiently so it is improper to
refer to aircraft wire as AWG.
NOTE: For an in-depth study of wiring
specifications, limitations, and repair, you should
refer to NA01-1A-505.
The basic wire identification code for circuits
is read from left to right, except circuit function
letters R, S, T, or Y. Look at figure 2-12 as you
read this section.
Unit number. Where two or more identical
items of equipment are in the same aircraft, use
prefix unit numbers 1, 2, 3, 4, etc., to differentiate
between wires and cables. To make it easier to
interchange items, identical wiring is located
in left and right wings, nacelles, and major
interchangeable structural assemblies, without
using the unit number. Use the unit number for
circuit functions R, S, T, and Y, only where
complete duplicate equipment is installed. Unit
numbers don't apply to duplicate components
within a single complete equipment, such as
duplicate indicators or control boxes.
C i r c u i t function l e t t e r ( e x c e p t R , S , T ,
and Y). The circuit function letter identifies the
circuit function (table 2-2). When using a wire
or cable for more than one circuit function,
the circuit function letter of the predominant
circuit applies. When functional predominance is
questionable, use the circuit function letter for the
wire or cable having the lowest wire number.
Wire number. The wire number consists of
one or more digits. It identifies the different wires
in a circuit. A different number is used for wire
