Quantcast Wood pole reinforcement

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TM 5-684/NAVFAC MO-200/AFJMAN 32-1082
minimum pole-setting depths are given in table 4-2.
good. In such cases, especially if the pole contains
several lines or equipment, pole reinforcing may be
In other types of soil, pole-setting depths need to be
a more economical (and fully satisfactory) solution
increased or decreased, in accordance with the local
than providing a new pole. The pole must be sound
utility's practice, dependent upon whether the
from about 15 inches (400 millimeters) above the
ground tends to be swampy or rocky.
ground line to the pole top, and preservative should
be applied under pressure to prevent spread of the
Table 4-2. Pole setting depth
groundline decay into healthy wood.
Pole length. overall
Setting depths
c. Pole treatment. Poles in place are exposed to
Straight lines
Curves, corners
weathering and decay, which is usually most severe
and points of
at the ground line. In some cases, the upper part of
extra strain
the pole will have decayed to only a small degree,
Feet
Feet
Meters
Feet
Meters
Meters
and preservative treatment to extend its useful life
5.5
30
. . . . 9.0
1.7
5.5 . . . . . . . . . . . . . 1.7
will be economical. Poles may have to be straight-
. . . , 9.0
6.0
1.8
6.0 . .. . . . . . . . . . . 1.8
35
6.5..
40
. . . . 9.0
6.0
1.8
ened because deterioration or replacement has
45
. . . . 9.0
6.5
2.0
7.0..
caused them to be out of line. Guying, raking, or
50
. . . . 9.0
7.0..
77.5 .
otherwise sustaining the pole load may permit line
55
. . . . 9.0
7.5
2.3
8.0
straightening, if the butt of the pole is kicked over
. . . . 9.0
8.0
2.4
8.5
60
while leaving the top of the pole in the same place,
. . . . 9.0
9.0
2.8
9.5 . . . . . . . . . .
70
or if both the top and the butt of the pole are moved
as necessary.  Moving the butt means that
4-18. Wood pole reinforcement.
groundline treatment will also be necessary. The
Pole reinforcement technology has developed sev-
cost of pole replacement, particularly of a large,
eral methods of pole repair which can restore poles
heavily-loaded pole, can justify considerable effort
to their original groundline strength. Engineer-
and expense in extending the useful life of a pole in
place. See section VI for information on treatment.
ing personnel should evaluate the selected method
to ensure that the proposed installation is ade-
4-17. wood pole replacement.
quate.
It is recommended that new poles be fully treated
a. Stub pole. A length of pole of the same size as
with a NRECA WQC pressure treatment to ensure
the existing pole, and long enough to extend from
that the maximum service life potential is obtained.
the butt of the pole to about 5 feet (1.5 meters)
Butt treatment and similar partial treatment meth-
above the ground line, is set flush alongside the
ods are not acceptable.
existing pole. Follow criteria for setting a new pole
a. Installation. When a new pole does not have to
and band it to the existing pole at the top and about
be replaced in the same h.ole as the old one, setting
15 inches (400 millimeters) above the ground line.
the new pole near the old location, including `attach-
Figure 4-7 shows details for fastening the stub pole
ment of the equipment and conductors to the new
to an existing pole.
pole before removing the old one, may be more con-
b. Steel reinforcing. If several poles need reinforc-
venient and safer.
ing, steel reinforcing may be more economical than
(1) Line wires. Before any pole is cut off, the
the use of stub poles. The steel reinforcement con-
top of the pole must be held or guyed in four direc-
sists of a "C" shaped galvanized steel section (as
tions. In most cases, the line wires can be relied on
shown in figure 4-8), which is pneumatically driven
to hold the pole in conformity with the line direc-
to below the pole butt and then strapped to the
tion, while guys or pike poles are required to hold it
existing pole. The equipment for driving the rein-
in the other directions.
forcing is specifically designed for the purpose, but
(2) Service-drop conductors. Free service-drop
its use will be more economical than digging Holes
conductors; do not count on them to hold a pole
because any strain might pull the service-drop
for several stub poles. Although the steel reinforcing
brackets off the buildings.
can be installed by in-house forces, it would prob-
(3) Energized replacement. If a pole must be
ably be advantageous to have this work done by a
replaced with conductors energized, the wire must
firm specializing in this service. Steel reinforcing
be properly covered with rubber protective equip-
also provides extra protection from vehicles in con-
ment designed for this purpose, so work on the pole
gested areas. Engineering is required to ensure
can be done safely as covered in section XV
proper installation since the overall strength of the
b. Pole setting. Poles need to be set in accordance
steel truss and pole combination depends on the
strength of the banding system.
with ground conditions. For normal firm ground,
4-10





 


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