that would affect structure integrity. Take
sonic readings in lines with the largest
cracks and follow up with a bore test if
decay is suspected.
4.6. CROSSARM INSPECTION AND
TREATMENT. Inspect crossarms during
structure inspections or when conditions
warrant a special inspection. Make periodic
inspections of spar arms and X-braces.
Inspect the crossarm thoroughly from each
pole in case of a multiple structure. Check
crossarms for any damage caused by
lightning, woodpeckers, etc. Inspect for
checks, splits, or decay pockets, particularly
at holes bored through the arm.
Note checks across the top of the crossarm
which may hold moisture. Bore the crossarm
from below to drain the moisture. Keep bore
holes at least I foot apart. Use increment
borer or brace and bit to inspect for decay.
NOTE: Because of the scarcity and high cost
of quality wood spar arms, the Mid-Pacific
region has been replacing deteriorated spar
arms with I-beams of a high-strength,
corrosive-re-sistant steel (Cor-Ten).
V. DETERMINING THE SERVICEABILITY OF
5.1. GENERAL. The decision to treat or
replace a decayed pole shall depend upon
the remaining strength or serviceability of the
pole. The permissible reduced circumference
of a pole is a good measure of serviceability;
it may be determined by using the following
discussion and tables.
5.2. DECAY CLASSIFICATION. Decay at
the groundline shall be classified as:
(1) General external decay,
(2) External pocket,
(3) Hollow heart, or
(4) Enclosed pocket.
External decay may extend around the pole
and cover a large area of the circumference
or it may be limited to a small area
representing only a portion of the circumfer-
ence. If the decay is limited to a portion of the
pole not exceeding 6 inches in width and 5
inches in depth, it shall be classified as an
"External Pocket," otherwise, external decay
shall be classified as "General External Decay."
5 . 3 . P E R M I S S I B L E R E D U C E D
CIRCUMFERENCE SAFETY FACTORS.
Wood pole transmission lines are designed
using a pole strength safety factor of 4 (SF
4), and the groundline circumference of a
pole is used as a measure of pole strength.
reduced circumferences (caused by general
external decay) and reduced safety factors.
Circumference reductions to compensate for
other categories of decay,
should be applied to the circumferences in
circumference and the corresponding pole
If the reduced circumference indicates a pole
safety factor less than that specified
or stubbed immediately. Poles meeting or
exceeding the specified safety factors should
be treated as specified in
as outlined in
The tables should be used in accordance
with the following instructions:
5.3.1. General external decay. - After
cutting away all decayed wood,
measure the circumference above or
below the decayed section to determine
the original (SF 4) circumference. Then
measure around the pole where the
d e c a y w a s r e m o v e d ; t h i s
m e a s u r e m e n t i s t h e r e d u c e d
circumference. Check the original and
reduced circumference. Check the
original and reduced circumferences
5.3.2. External pocket. - Remove
d e c a y e d w o o d a n d m a k e
measurements of the dept h and width
of the pocket. Measure the pole for the
original (SF 4) circumference. Refer to
reduction. After the circumference
9 (FIST 4- 6)