Lesson 2/Learning Event 5
b. Cable Forms. Cables are formed into single-leg and multileg types
to meet application requirements. Assume, for example, that a cable will be
used to interconnect the equipment side of line protectors to horizontal
terminal strips. The cable is formed into a single-leg type for attachment
to the line protectors using the vertical fanning strip. The cable is then
run either overhead or through the underfloor cable vault to the horizontal
terminal strips where it is formed into multileg types.
(1) Single-leg form (figure 2-7).
A single-leg cable form is made by
paralleling all the wires in the unsheathed cable portion and sewing
(lacing) the grouped wires at the exit of the skinners. The skinners may
exit either in pairs or quads, depending on the type of cable. In a paired
cable, the wires are twisted together in pairs; in a quadded cable, the
wires are twisted together in groups of four. The sewing procedure always
starts with the forming of the butt, proceeding toward the end wires.
(2) Multileg cable form (figure 2-8). A multileg cable form is made by
dividing the wires into groups and paralleling the wires in the groups. The
cable sewing always starts with the butt first, proceeding up the paralleled
wires to the end wires, bringing out the skinners on the top leg.
Then
follows the sewing procedures on the remaining three legs, with skinners
dropping out where they can attach to horizontal terminal strips.
c. Typical Installation.
Typical installations
of
single-leg
and
multileg cable forms are shown in figures 2-9 and 2-10.
d. Termination of Skinners.
Although the task of installing a cable
usually is performed by an installation team, the technical controller may
be called upon to assist.
Specifically, he will be asked to attach
skinners, because the job is time consuming and can be conveniently divided
into sectional work.
Moreover, after installation has been completed the
technical controller may have to disconnect and reconnect pairs during
maintenance tests.
For these reasons he should be familiar with the
recommended method shown in figure 2-11.
105
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