Tall industrial structures, from cranes to temporary towers, are closely regulated by the FAA. The agency asserts guidelines for visual safety, ensuring that proper lighting is available for detection. Aircraft pilots rely on obstruction lighting to evade the structures at night.
For wind turbines, the FAA provides several recommendations in relation to the type of lights, flashing efficiency rates and spacing during installation.
FAA Regulations and Wind Turbines
The application of obstruction lighting in wind farms is governed in FAA Advisory Circular AC 70/7460-1K (Chapter 13). When a group of wind turbines is used to form a ‘farm’ the agency asserts that only three turbines exceeding 200 feet (from ground level) can be utilized.
Interestingly, not all of the units require obstruction lighting.
According to the FAA, operators must carefully install the lights, so that spacing does not exceed ½ statute mile. By definition, a statute mile is equivalent to 5,280 feet or 1,609.34 meters.
Flashing and Durability
The FAA cited Type L-864 red flashing luminaries as the standard for illumination at night. In most cases, these are strobe lights (with flashing capabilities), which are used for visual notification. When multiple flashing lights are applied in a wind turbine farm, the luminaries must have simultaneous flashing patterns.
As for materials used, the FAA recommends the use of aluminum (under IFH-1710). At high altitudes, the units are exposed to devastating winds, rough weather and debris. Because of this, ease of maintenance is prioritized by the FAA.
Field-repairable features are required to streamline access and reduce complex maintenance tasks. For obstruction lights on wind turbines, this includes an accessible hinged door that can be locked and secured for protection. To reduce frequency of maintenance, LED lights can be utilized. The luminaries offer 50,000+ hours of illumination and support compatibility with low voltage (DC) sources and photocell sensors.