Figure 4-48 shows that the face of any pole is on the
inside of any curve the pole may have. This allows the
wire strain on the crossarm to be against the curve of the
pole. This also dictates positioning of the gain on the
face of the pole, except for gains on comer poles, when
lower crossarms are mounted at a 90-degree angle to the
main distribution line.
The roof or top of the pole (fig. 4-48) is cut sloping
at a 15-degree angle from the face to the back of the
pole; however, on the new pressure-treated poles, roofs
are not required.
A gain should be one-half inch deep in the center,
slightly concave, and located 12 inches from the top of
the pole. The width of the gain should be the height of
the crossarm to be used. Spacing of succeeding gains
depends on the voltage of the lines to be placed on that
level. This information is contained in the project
specifications and drawings for any new work for which
you are tasked.
To drill holes for mounting crossarms, use a
template that can be used to mark the center, or draw
two diagonal pencil lines across the gain. The
intersection of these two lines determines the center of
Figure 4-48.The parts of a pole.
the gain and the place to drill the hole. The nominal size
hole is 1 1/16 inch for a 5/8-inch through bolt.
The depth for a pole hole depends on the length of
the pole and the composition of the soil. A hole in firm,
rocky terrain does not need to be as deep as a hole in soft
soil. Table 4-1 gives recommended depths for poles
from 20 to 60 feet long in firm soil and in rock.
A pole set in sandy or swampy soil must be
supported by guys or braces, or by cribbing. "Cribbing"
means placing some firm material around the part of the
pole that is below the ground. One method of cribbing is
to sink an open-bottom barrel in the hole, set up the pole
in the barrel, and then fill the space around the base of
the pole with concrete or small stones after the pole has
been plumbed (brought to the vertical). Another
method of cribbing is shown in figure 4-49.
There may be a power-driven hole digger available,
but in the absence of one of these, the holes must be dug
by hand tools (fig. 4-50). You use a "digging bar" to
loosen the soil. You can remove about the first 2 feet of
depth with a short-handled shovel. Below that, you
loosen the earth with an earth auger or long-handled
shovel, and haul it up with a long-handled device, called
A hole should have a diameter about 6 inches larger
than that of the base of the pole to allow room for
tamping backfill. It should be a little larger at the
bottom to allow for plumbing the pole.
When a earth auger is available, the job of erecting
poles is relatively simple. A sling is placed around the
approximate midpoint of the pole, and the winch heaves
it up, and it is held in place by a pole claw (fig. 4-51).
Table 4-1.Depth for Setting Poles in Soil or Rock