members must be stationed along the way to establish a
chain of signal communication from the head of the line
back to the line truck.
Placing the Neutral Conductor
A neutral conductor should always be placed on a
center crossarm pin or on a pole-top pin. Butting the
neutral on a center pole pin gives the lineman a clear
space around the pole to climb through; that is, it
ensures that the hot wires are a considerable distance
When the conductors have been hoisted in place on
the crossarms and dead-ended on one end, you are ready
to start "pulling in"; that is, heaving on the conductors
until each has been raised to proper sag. You can do this
with a tackle equipped with cable grips like those shown
in figure 4-65 or individually, using a cable grip and a
A cable grip is a clamp device that grips the wire
tightly when a strain is applied to the grip.
When you are pulling two or more wires at once, it
is best to use the equalizer, as shown in figure 4-65. This
device distributes the strain equally on all the wires.
Measuring the Sag
When wires have been pulled to approximately the
desired sag, a lineman goes to the center span to
measure the sag. Measurement at the center of each
span ensures uniformity.
Three common ways of
measuring sag are by dynamometer, by timing
vibration, and by the use of targets.
is an instrument that is installed in the pulling line and
that measures the strain of the pull. It is used in
conjunction with a chart that gives the desired pull
tension for a given conductor size, span length, and
temperature. A traction dynamometer, also installed in
the pulling line, provides direct readings on the face of
TIMING VIBRATION.The timing-vibration
process is done by striking the wire sharply near one of
the pole supports and by timing with a stopwatch, the
interval that elapses as the impulse from the blow
travels to the next pole and returns. This system is not
accurate when wind is swinging the line or when the line
is being worked on in an adjacent span.
Figure 4-65.Pulling wires with an equalizer.