43. CATENARY LIGHTING
Lighted markers are
available for increased night conspicuity of
high-voltage (69KV or greater) transmission line
catenary wires. These markers should be used on
transmission line catenary wires near airports,
heliports, across rivers, canyons, lakes, etc.
The lighted markers should be manufacturer
certified as recognizable from a minimum
distance of 4,000 feet (1219m) under nighttime
conditions, minimum visual flight rules (VFR)
conditions or having a minimum intensity of at
least 32.5 candela.
The lighting unit should
emit a steady burning red light. They should be
used on the highest energized line. If the
lighted markers are installed on a line other
than the highest catenary, then markers
specified in paragraph 34 should be used in
addition to the lighted markers. (The maximum
distance `:' between the line energizing the
lighted markers and the highest catenary above
the lighted marker should be no more than 20
feet (6m).) Markers should be distinctively
shaped, i.e., spherical, cylindrical, so they
are not mistaken for items that are used to
convey other information. They should be visible
in all directions from which aircraft are likely
to approach.
The area in the immediate
vicinity of the supporting structure's base
should be clear of all items and/or objects of
natural growth that could interfere with the
line-of sight between a pilot and the
structure's lights. Where a catenary wire
crossing requires three or more supporting
structures, the inner structures should be
equipped with enough light units per level to
provide a full coverage.
Catenary lights are now
available which can be mounted on the energized
power line and be lighted [energized] by the
electrical field of the power line itself. The
P&R PowerLITE cylindrical light is some 24"
long, steady red, and emits more than the 32,5
candella of the FAA advisory. PowerLITEs are
most effective, and smaller, on 230500 KV
systems. They need much more capacitance areas
at 69-132 KV.
Note that the FAA specifies
that the "lights be installed on the highest
energized line. If the lighted markers are
installed on a line other than the highest
catenary then [passive ] markers should be used
[on the shieldwire] in addition to the lighted
markers."
The ideal arrangement from
the standpoint of initial cost and installation
for both day and night conspicuity is to have
the lighted marker mounted on the shield wire
next to the passive daytime marker. Contact P&R
for the new ShieldLITE product line.
34. MARKERS
Markers are used to
highlight structures"" when it is impractical to
make them conspicuous by painting. Markers may
also be used in addition to aviation orange and
white paint when additional conspicuity is
necessary for aviation safety. They should be
displayed in conspicuous positions on or
adjacent to the structures so as to retain the
general definition of the structure. They should
be recognizable in clear air from a distance of
at least 4,000 feet (1219m) and in all
directions from which aircraft are likely to
approach. Markers should be distinctively
shaped, i.e., spherical or cylindrical, so they
are not mistaken for items that are used to
convey other information. They should be
replaced when faded or otherwise deteriorated.
a. Spherical Markers:
Spherical markers are used to identify overhead
wires. Markers may be of another shape, i.e.,
cylindrical, provided the projected area of such
markers will not be less than that presented by
a spherical marker.
1. Size and Color.
The diameter of the markers
used on extensive catenary wires across canyons,
lakes, rivers, etc., should be not less than 36
inches (91 cm). Smaller: 20-inch (51 cm) ,
spheres are permitted on less-, extensive power
lines or on power lines below 50 feet (15m)
above the ground and within 1,500 feet (458m) of
an airport runway end. Each marker should be a°
solid color such as aviation orange, white, or
yellow.
2. Installations.
(a) Spacing. Markers
should be spaced equally along the wire at
intervals of approximately 200 feet - (61 m) or
a fraction thereof. Intervals between markers-
should be less in critical area near runway ends
(i.e., 30 to 50 feet (10m to 15m)). They should
be displayed on the highest wire or by another
means at the same height as the highest wire.
Where there is more than one wire at the highest
point, the markers may be installed alternately
along each:
if the distance between
adjacent markers meets the spacing standard.
This method allows the weight and wind loading
factors to be distributed.
(b) Pattern. An
alternating color scheme provides the most
conspicuity against all backgrounds. Mark
overhead wires by alternating solid colored
markers of aviation orange, white, and yellow.
Normally, an orange sphere is placed at each end
of a line and the spacing is adjusted (not-to
exceed 200 feet (61m)) to accommodate the rest
of the markers. .When, less than four markers
are' used they should all be aviation orange.
