Rubber Insulating Insulator Hoods
Pin type or post type of distribution primary
insulators can be covered by hoods. The insulator hood
properly installed will overlap the line hose, providing
the lineman with complete shielding from the
Insulator hoods, like all other rubber insulating
protective equipment, must be treated with care, kept
clean, and inspected at regular intervals. Canvas bags
of the proper size attached to a handline should be used
to raise and lower the protective equipment when it is
to be installed and removed.
handles are knotted through holes in the overlap area of
Rubber Insulating Blankets
Odd-shaped conductors and equipment usually
can be covered best with a rubber insulating blanket.
The blankets, like other protective equipment, must
receive careful treatment. The rubber insulating
blankets are stored in canvas rolls or metal canisters to
protect them when they are not in use. The blankets can
be held in place by ropes or large wooden clamps.
In-service care of insulating blankets is specified
in ANSI/ASTM D1048 standard.
A conductor cover, fabricated from high-dielectric
polyethylene, clips on and covers conductors up to 2
inches in diameter. A positive air gap is maintained by
a swinging latch that can be loosened only by a one-
quarter turn with a clamp stick.
Insulator covers are fabricated from high-
dielectric polyethylene and are designed to be used in
conjunction with two conductor covers. The insulator
cover fits over the insulator and locks with a conductor
cover on each end. A polypropylene rope swings under
the crossarm and hooks with a clamp stick, thus
preventing the insulator cover from being moved
upward by bumping or wind gusts.
High-dielectric-strength polyethylene crossarm
covers are used to prevent tie wires from contacting the
crossarm when conductors adjacent to insulators are
being tied or untied. It is designed for single- or
double-arm construction with slots provided for the
double-arm bolts. Flanges above the slots shield the
ends of the double-arm bolts.
Polyethylene-constructed pole covers are
designed to insulate the pole in the area adjacent to
high-voltage conductors. The pole covers are available
in various lengths. Positive-hold polypropylene rope
Hard hats, or safety hats, are worn by linemen,
cablemen, and groundmen to protect the worker
against an impact from falling or moving objects and
against accidental electrical contact of the head and
energized equipment. In addition, hard hats protect the
worker from sunrays, cold, rain, sleet, and snow. The
first combined impact-resisting and electrical-
insulating hat was introduced in 1952. The hat was
designed to roll with the punch by distributing the
force of a blow over the entire head. This feature is
accomplished by a suspension band which holds the
hat about an inch away from the head and lets the hat
work as a shock absorber.
The hard hat is made of fiber glass, or plastic
material, and has an insulating value of approximately
20,000 volts. New helmets are manufactured to
withstand a test of 30,000 volts without failure. The
actual voltage that the hat will sustain while being
worn depends upon the cleanliness of the hat, weather
conditions, the type of electrode contacted, and other
variables. The wearing of safety hats by linemen and
cablemen has greatly reduced electrical contacts.
Physical injuries to the head have been practically
eliminated as a result of workers on the ground wearing
protective helmets. The Occupational Safety and
Health Act of 1970 and most companies' safety rules
require linemen, cablemen, and groundmen to wear
safety hats while performing physical work.
Specifications for safety hats are found in ANSI
Standard Z89.1, Protective Headwear for Industrial