Table 2-4. Mechanical and dielectrical strength of strain insulators.
b. Location of strain insulators in exposed guys. Whenever practicable, locate strain insulators
in exposed guys outside the zone of exposure.
(1) Locate the strain insulators at least 8 feet (2.43 m).
(2) When the guy is exposed to a power line by being attached to a jointly used pole, do not
use a strain insulator near the top of the pole. The effect of a strain insulator is nullified if it is within the
zone of exposure.
PART D - PROTECTING POLES AGAINST LIGHTNING
1.
General. The installation of lightning protection wires on poles is generally confined to areas
where there is a possibility of severe lightning. The pole locations where lightning protection must be
installed will be specified in the detailed plan. Bare copper or copper-steel wire may be attached to the
pole by means of galvanized staples to provide lightning protection. The staples are spaced every 18
inches (46 cm). The location of the vertical run of the protection wire on the pole depends on the types
of attachments on the pole. On poles carrying open wire, only the vertical run usually is located on the
face of the pole and just clear of the crossarms. On poles carrying cable only, the vertical run usually is
located on either the face or the back of the pole. For lightning protection purposes, poles supported by
pole-to-tree or pole-to-pole guys are considered to be unguyed poles.
a. Installation of lightning protection on poles supporting open wire only.
(1) Extend the protection wire down from the roof of the pole on the side of the pole opposite
the proposed vertical run. Run the protection wire up over the roof of the pole and down the pole to a
point above ground level. Cut the wire at this point. Keep the wire straight and flush against the pole.
Attach the wire to the pole with staples.
2-35
SS0439
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