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 T M5-684/NAVFAC MO-200/AFJMAN 32-1082
NOT GAIN
POLE
SQUARE
PUSH BRACE
(USE LINE POLE)
DETAIL OF POLE
DETAIL OF PLANK ATTACHMENT K
Figure 4-21. Wood-pole push brace
have been set according to the need to bypass light-
a. Porcelain. Porcelain guy strain insulators are
ning strokes around the wood. The insulator should
usually of the interlocked (Johnny ball) type. The
be replaced if deterioration or damage affects its
porcelain is in compression. If breakage occurs the
strength. When a wood insulator replacement is
guy is relaxed, but, due to the interlinkage, does not
needed, provide a fiberglass insulator instead.
part. In replacing the insulator, consideration
should be given to the cause of failure. If the broken
used for guys in lieu of wood. Advantages are their
insulator was too small, replace with a larger and
indefinitely long life; their imperviousness to mois-
stronger one.
ture; and their ability to withstand a direct stroke of
b. Wood. Wood guy insulators may have been in-
lightning without bursting. They do not require arc-
stalled, particularly on higher voltage lines, because
ing horns to bypass the lightning stroke. Fiberglass
of their superior impulse resistance. The size and
insulators are shorter than wood insulators, so they
length of the wood member used would have de-
take up less space. Corrosion or rusting of the metal
pended on the strength required and the voltage of
and fittings will ultimately be the reason for their
the circuit. The wood should have been treated with
replacement.
a nonconducting preservative. Arcing horns may
4-28
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