T M 5-684/NAVFAC
Figure 4-8. Steel reinforcing for a wood pole
b. Weathering. Crossarms may lose their strength
the same schedule and in the same way as the
because of cracks caused by weather separations. If
crossarm it supports.
cracks are near through-bolts or dead-end bolts, re-
place the arm because the crack may allow the bolt
4-21. Pole platforms.
to pull through.
Platforms supported by one or more poles are used
c. Twisting. Twisted arms may be caused by an
to mount transformers, regulators, or other heavy
unbalanced strain or insufficient guying. Where
equipment above-ground. They are usually built
twisted arms impair the safety of the line, or create
with wooden stringers and flooring, or with wood
an unsightly appearance, the condition should be
flooring on steel beams. Many platforms now in use
are composed of untreated timbers; these should be
4-20. Pole braces.
treated with suitable preservative to extend their
useful life. When replacement is necessary, use fully
Braces are used to position crossarms in relation to
treated timbers or consider installing ground-
the supporting structure. Only metal braces should
be used. A crossarm brace should be maintained on