With the air hose in the end ofthe duct and the cord free
to run out, you will be able to blow the cloth through to
the next opening, even on a long run of duct.
Cleaning ducts is accomplished by rodding.
Quick-coupling duct rods (about 1 feet long and 1 inch
in diameter) are connected together with a wire brush
or other duct rod leader at the head to facilitate
cleaning. The rods may be pushed through manually or
by means of power equipment. A 12-gauge galvanized
steel wire attached to the leader is left in the duct for the
cable pulling crew.
Moisture inside a cable causes deterioration of the
insulation; therefore. precautionary measures should
be taken to avoid the accumulation of moisture inside
the cables. Before pulling a cable. ensure that the cable
ends are sealed against moisture invasion.
Figure 4-47 shows a number of ways to rig
manholes for cable pulling. View A shows the cable
pulley attached to a timber block which, in turn, is
supported by a wedge. In view B, the pulley is shown
attached to the manhole wall by means of an embedded
eye. If you use this method. make sure that the lower
sheave is in line and level with the duct in which the
cable is to be pulled. To prevent injury, to the cable by
sharp edges. line the duct mouth with a shield.
Either of the above methods will probably be
satisfactory for most of the jobs you will handle.
Sometimes. however. more complex rigging is called
for, especially in cases when the cable requires heavy
pulling. For jobs of this nature, you will find the other
views in figure 4-47 helpful.
When pulling cables into a long duct. use a feeding
tube or bell for applying a lubricant at the duct mouth.
Make sure you use the lubricant specified by the
manufacturer of the cable.
Make a plank runway to support the reel for
movement over areas where dirt, cinders, or crushed
stone might damage the cable. All cable reels are
marked with an arrow. indicating the direction in
which they must be rolled. Comply with this arrow
when placing the reel at a manhole so that it turns in
the proper direction as cable is pulled from the reel.
Place the reel as near as practical to the manhole and
raise it on reel jacks just enough to clear the ground.
Figure 4-48 shows a reel in proper position over the
manhole so that the bend in the cable is not reversed as
the cable is unreeled. Notice the scuff boot at the edge
Figure 4-47.Manhole rigging for pulling cables.
Figure 4-48.Reel in proper position.