![]() ![]() Twenty-five (25) feet (7.62 m) is the maximum allowable distance between the highest wire installed with marker balls and the highest wire without marker balls, and shall not violate the sag requirements of the transmission line design.ĭ. Wire Sag, or droop, will occur due to temperature, wire weight, wind, etc. When less than four markers are used, they should all be aviation orange. Normally, an orange marker is placed at each end of a line and the spacing is adjusted to accommodate the rest of the markers. Unlighted markers should be installed by alternating solid-colored markers of aviation orange, white, and yellow. An alternating color scheme provides the most conspicuity against all backgrounds. This method distributes the weight and wind-loading factors. Where there is more than one wire at the highest point, the markers may be installed alternately along each wire if the distance between adjacent markers meets the spacing standard of 200 feet or less. They should be displayed on the highest wire or by another means at the same height as the highest wire. There should be less space between markers in critical areas near runway ends. Unlighted markers should be spaced equally along the wire at approximately 200-foot (61-m) intervals, or fraction thereof. Each marker should be a solid color, specifically aviation orange, white, or yellow.Ī. Smaller 20-inch (51-cm) spheres are permitted on less extensive catenary wires or on power lines below 50 feet (15 m) AGL and within 1,500 feet (458 m) of an airport runway end. The diameter of the markers used on extensive catenary wires (catenary wires that cross canyons, lakes, rivers, etc.) should not be less than 36 inches (91 cm). Markers may be of another shape, i.e., cylindrical, provided the projected area of such markers is not less than that presented by a spherical marker. Spherical markers are used to identify overhead wires and catenary transmission lines that are less than 69 kV. They should be replaced when faded or otherwise deteriorated. Unlighted markers should be distinctively shaped, i.e., spherical or cylindrical, so that they are not mistaken for items that are used to convey other information. They should be recognizable in clear, daytime visibility from a distance of at least 4,000 feet (1,219 m) and in all directions from which aircraft are likely to approach. Unlighted markers should be displayed in conspicuous positions on or adjacent to the structures so as to retain the general definition of the structure. Unlighted markers may also be used in addition to aviation orange and white paint when additional conspicuity is necessary for aviation safety. Unlighted markers are used to identify structures and to make them more conspicuous when it is impractical to paint them. In some circumstances, such as river and canyon crossings, the FAA recommends an alternating pattern of Orange, Yellow, and White. In some cases, these colors prove to be more visible, depending on the surrounding terrain. 557) however, yellow and white are available as an option. ![]() Our standard color is “International Danger Orange ” (U.S. The Marker is then securely bolted around the wire, clamping down on the bushings. This Marker Ball installs easily on any wire 1/8″ – 1″ (custom wire sizes are available) through the use of two UV-resistant neoprene strip bushings installed on the wire to match the diameter of the openings (boss) in the Marker. Available in Orange (standard), Yellow or White.Designed for neutral wires, guy wires, and conductor wires up to 69KV only.Requires only four bolts to clamp it to the wire.Heavy duty construction, made from UV-stabilized ABS plastic with UV-resistant Korad™ coating.Available in four diameters: 9″, 12″, 20″ or 24″.Marker Balls are typically used in airport and heliport approach areas and where power lines span long distances crossing canyons, lakes and rivers. This product is available in our webstore – Shop NowĪerial Marker Balls help save lives and protect expensive infrastructure by making power lines and guy wires more visible to low-flying planes and helicopters. ![]()
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