Quantcast Section XVI- Aerial Lift Requirements

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TM 5-684/NAVFAC MO-200/AFJMAN 32-1082
(a) Fasten the wire tongs to the conductor.
(a) Water resistiuity. Water having a resistiv-
(b) Remove the tie or clamp from the conduc-
ity greater than 1500 ohm-centimeters can usually
be obtained from city water system hydrants. This
tor.
(c) Move the conductor clear of the work area
is an acceptable low-level resistivity. Water resistiv-
and secure the wire tong.
ity changes inversely with temperature and must be
(d) Remove old insulator.
measured periodically during washing operations,
(e) Mount new insulator.
especially in hot weather. In no case should water
(f) Return conductor to insulator.
be used having a resistivity of below 1,000 ohm-
(g) Tie or clamp conductor to insulator.
centimeters. No soap, detergents, anti-freeze, or al-
(h) Remove wire tongs.
cohol should be added.
(3) Crossarms: In replacing crossarms, apply
(b) Nozzle type. A jet nozzle is more suited to
steps (a), (b), and (c) for all lines. Then remove
transmission (high-voltage) systems because wind
crossarm and insulators and replace with new cross-
effects the spray less and the spray range is greater.
The spray nozzle is suited for distribution (medium-
arm with new insulators in place. Then apply steps
voltage) systems.
(f), (g), and (h).
d. Washing energized insulators. Hand cleaning
(c) Apparatus. Consult manufacturers when
washing nonceramic insulators. Bushings made of
of de-energized insulators is described in chapter 3,
porcelain must be treated with great care and the
section IV ANSI/IEEE 957 provides a guide for
effects of water pressure and volume and the me-
cleaning insulators.
(1) Facility procedures. Each facility should de-
chanical support provided the bushing must be con-
velop procedures based on their level of voltages,
sidered. Energized washing of surge arresters may
contaminants, and available equipment. Using ad-
impose severe electrical stresses on the arresters
due to voltage imbalance and should not be done
vice from the local utility concerning their energized
without the consent of the arrester manufacturer.
insulator washing practices is recommended.
(2) Energized cleaning methods. Energized
(4) Safety. Follow facility rules and general in-
cleaning methods include the use of high pressure,
dustry practices as covered in ANSI/IEEE 957. The
medium-pressure, and low-pressure water; com-
OSHA safe working distance (from Table V-l of
pressed air with abrasive dry cleaning compounds;
Subpart V, Section 1926.950) is the minimum dis-
and wiping with burlap cleaning hammocks using
tance recommended for personnel adjacent to ener-
hot sticks. All of these procedures are covered in
gized objects at any time. This distance applies to
ANSI/IEEE 957.
the phase-to-phase voltage and is 2 feet (0.6 meters)
(3) Technical considerations of pressurized wa-
for 2.1- to 15-kilovolt energized parts and 2.33 feet
ter cleaning. Certain items influence the effective-
(0.71 meters) for 15.1- to 35-kilovolt energized
ness of pressurized water cleaning performance and
parts.
e. Other procedures. Cutting out and replacing
the leakage current that can pass to the operator's
body from the water stream. These items are the
live conductors requires supporting the conductors
nozzle conductor distance, the water's resistivity,
and providing a temporary jumper to bypass the
current while the splice is completed. The bypass
the water pressure, and the nozzle-orifice diameter.
uses hot-line clamps as `does tapping a conductor.
Wind can interfere with the efficiency of the water
Installation of hot-line clamps, armor rods, and vi-
spray. The washing interval must be such as to
bration dampers should follow manufacturer's hot-
avoid flashover accidents during hot-line washing,
line instructions. Phasing-out requires a phase-
which can occur when the acceptable limit of con-
tamination has been exceeded. Some points, covered
tester, which should be connected in accordance
in more detail in ANSI/IEEE 957, are as follows:
with the manufacturer's instructions.
Section XVI-AERIAL LIFT REQUIREMENTS
4-66. Aerial lift construction.
Subpart V Paragraph 1926.556 and to be at least as
safe as the equipment was before modification.
Aerial lifts are required to be constructed to meet
ANSI/SIA A92.2. Aerial lifts can be field modified
4-67. Aerial lift specifics.
for uses other than those intended by the manufac-
OSHA has defined equipment which must meet
turer, provided the modification has been certified
aerial lift rules and electrical tests.
in writing by the manufacturer or other equivalent
a. Type of aerial lifts. Aerial lifts include the fol-
entity (such as a nationally-recognized testing labo-
lowing types of vehicle-mounted aerial devices used
ratory) to conform with ANSI/SIA A92.2 and OSHA
4-35





 


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