For an individual turbine it is recommended to fit a 5NM white light, flashing Morse Code “U”, mounted at a minimum height of 15 metres above the Highest Astronomical Tide (HAT) but below the turbine blades. As it should be seen from all directions, a minimum of two are recommended. The tower should also be painted yellow all around to a height of 15 metres above the HAT or to the height of the AtoN.
For marking groups of structures (wind farms), the recommendation calls for a 5NM yellow light on each Significant Peripheral Structure (SPS) which should be seen in all directions. This requires two or three lights and it is recommended that they are synchronised. It is further recommended that all SPS lights are synchronised. In the case of large wind farms the SPSs should not normally be more than 3NM apart. Selected Intermediate “IPS” structures on the periphery of a wind farm, other than the SPSs, should be marked with flashing yellow lights, with a range of not less than 2NM. The flash character should be distinctly different from those of the SPSs. The lateral distance between an SPS and intermediate structure should not be greater than 2NM.