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 TM 5-684/NAVFAC M O - 2 0 0 / A F J M A 3 2 - 1 0 8 2
APPENDIX C
ADDITIONAL WOOD POLE DATA
C-1. Related pole data.
of southern yellow pine and western red cedar.
Douglas fir, western larch, red or jack pine,
This appendix provides related data on wood poles
lodgepole pine, or ponderosa pine are used where
which is not readily available in regard to general
available.
factors affecting pole life. Understanding the influ-
ence of these variables will help maintenance work-
C-5. Influence of local conditions.
ers understand what contributes to the life of a
Preservative treatment only delays the ravages of
wood pole installation both by the quality of its
pests and fungus, and does not eliminate pole decay.
initial treatment and by the actions of the environ-
Local conditions will have a direct influence on the
ment in which the pole is installed.
speed of decay and directly affect the mechanical
C-2. Why wood poles fail.
strength of poles. Pole strengths must be main-
tained above definite minimum requirements to
Wood poles generally fail because of pest damage or
meet safety requirements.
from wood-rotting fungi. A good preservative treat-
a. Adequate strength. Poles must be maintained
ment discourages both. The ability of treated poles
at all times to withstand the applicable loads result-
to resist deterioration depends principally upon the
ing from the conductors and equipment weights car-
thoroughness and quality of the original preserva-
ried, as well as the influence of weather conditions.
tive treatment and to a lesser extent on the type of
In the United States, three loading districts based
wood and local climatic conditions.
on weather conditions are recognized by the NESC.
C-3. Initial installation.
These loading districts are designated as light, me-
dium, and heavy. Loading districts are indicated on
Maintenance personnel should be familiar with how
the general loading map of the United States con-
much pole life is influenced by the quality of the
tained in the NESC.
preservative treatment. It is recommended that re-
b. Cause of damaging actions to wood poles. In-
placement wood poles and crossarms be produced
sects and other pests can attack poles in most geo-
by a treatment plant which is under the National
graphical areas. Termites, wood-boring beetles, and
Rural Electric Cooperative Association's (NRECA)
even carpenter bees and ants, may cause serious
wood quality control (WQC) program. Each wood
damage. Poles that are heavily infested with insects
pole and crossarm should bear the WQC symbol.
attract wood-damaging birds, such as woodpeckers.
This program was set up by the Rural Electrifica-
Fire and improper handling of poles during instal-
tion Administration (REA) with NRECA to ensure a
lation or maintenance can also cause damage.
source of high quality treated wood products for
utility company purchasers. This source should
(1) Termites and other insect damage.
eliminate wood products that have been damaged or
(a) Termites. Two classes of termites attack
improperly prepared by a treatment plant.
poles: the ground-dwelling termites, which are
a. Pole damage. Wood undergoing treatment can
found in practically every state; and the dry-wood
be damaged by too high a temperature or pressure
(or aerial) termites found only in the south. Gener-
or both; use of overseasoned wood; undetected de-
a l l y , the same m e a s u r e s taken to prevent
fects; and improper handling or storage methods.
decay-good preservative treatment-also prevent
b. Improper preparation. Shallow or erratic pen-
termite attack.
etration, low preservative retention, and inad-
(b) Ants. Black and brown carpenter ants are
equate toxicity and permanence of preservative oc-
often a serious problem, especially in cedar poles in
cur when the wood treatment plant has an
the northeastern states. The ants enter the pole
inadequate quality control program resulting in in-
through a check (separation along the grain of the
accurate, inadequate, or uneven treatment cycles
wood occurring across the annual rings) or injury
during the treatment process. Most wood preserva-
and construct galleries that seriously weaken the
tives are restricted-use pesticides which can only be
pole near the ground line. Unlike termites, they do
applied by certified applicators.
not use the wood for food.
(c) Control. Ants may be effectively de-
C-4. Types of wood.
stroyed by injecting about one pint (0.5 liter) of an
Overhead electric distribution circuits and equip-
approved termite repellant into the interconnected
ment are most commonly supported on wood poles
galleries. This can be done with an ordinary grease
C-l
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