TM 5-684/NAVFAC MO-200/AFJMAN 32-1082
4-7. Voltage terminology usage in this
work, is the one used in this manual, unless other-
wise stated. Therefore, primary circuits have a
medium-voltage rating; secondary circuits have a
The convention understood by most persons quali-
fied to perform various electric line-work opera-
tions, that is, for aerial, underground, and at-grade
Section III - TYPES OF MAINTENANCE
4-8. Component line maintenance.
nents mentioned assumes all work will be done on
unenergized lines (unless specifically noted other-
The various components which make up an over-
wise) and that all clearance procedures required to
head line system include poles to carry and insula-
provide service, as mandated by TM 5-682, NAF-
tors to support the line, along with line connectors
VAC P-1060, or AFM 32-1078, have been followed.
and guys. Most poles encountered will be wood, and
most primary line conductors will be bare. There
4-9. Other types of line maintenance.
are conditions, though, which justify the increased
Trees adjacent to overhead lines pose a line clear-
cost of metal or concrete poles or primary overhead
ance problem, requiring both checking for interfer-
insulated lines or cables. Increasing use of armless
construction will minimize, but not completely
ences and trimming on a planned time cycle. Main-
eliminate the use of crossarms. Pad-mounted,
tenance methods on energized overhead power lines
compartmental-type transformers are also replac-
require special training and tools to meet safety
ing, to a large degree, many unaesthetic aerial plat-
requirements, but can reduce service interruption
form-mounted, transformer installations. The dis-
times where operational requirements do not per-
mit the necessary outage period.
cussion of maintenance necessary for the compo-
Section IV - WOOD POLES
4-10. Life span of wood poles.
in figure 4-3. The format shown should be revised
as needed to meet local requirements.
The average life span of a full-length pressure-
(1) Interpretation of pole brands. An under-
treated wood pole can be maintained and even ex-
standing of the brands on the side of a pole is nec-
tended another 10 to 20 years with a proper inspec-
essary for proper inspection, record keeping, and
tion, treatment, and reinforcement program.
reporting. An example is shown in figure 4-4. The
4-11. Supplementary data on wood poles.
brand is near eye level and is generally burned into
the wood, though some pole suppliers use a counter-
Pertinent information is covered in appendix C on
sunk aluminum disk.
why poles fail, initial installation, types of wood
(2) Pole brand indications. The codes for spe-
used for poles, influence of local conditions, and
cies and preservatives treatments are as follows:
(a) Timber species are coded as SP-south-
4-12. Wood pole record keeping and inspec-
ern pine; WC-western red cedar; DF-Douglas fir;
WL-western larch; NP-northern (red or Jack)
Proper record keeping is the basis for a systematic
pine; LP-lodgepole pine; WP-ponderosa pine.
program of pole inspection and maintenance. These
(b) Preservatives are the oil-borne type
records will determine courses of actions based on
coded as A for pentachlorophenol; B for copper
actual examinations, eliminate much guesswork,
naphthenate; C for creosote, and the water-borne
extend actual pole life, and accumulate the histori-
type coded as CCA for chromated copper arsenate
cal data required to evaluate future pole mainte-
and ACZA for ammoniacal copper zinc arsenate.
Only copper naphthenate is a nonrestricted-use pes-
a. Essential record data. The first point is to
record the pole location, identification number, date
(c) Retentions are shown with a number for
of installation, and a manufacturer's pole brand.
the pounds per cubic foot. On poles which show no
Then poles should be rated based on the initial pole
retention figure, the pole was not pressure treated
scheduling inspections. Ratings should indicate
and should be rejected.
soundness of pole, any treatment provided during
(3) More data. See AWPA M6 for more complete
inspections, and any failed poles marked for safety
information on brands.
because replacement or reinforcing is needed imme-
b. Initial pole scheduling inspections. Two types
diately. A sample format for recording data is shown
of initial pole scheduling inspections should be pro-