33 CFR 67.20-5: -5 Obstruction lights.

The obstruction lights shall be white lights as prescribed in Subpart 67.05 of this part. The lights shall be of sufficient candlepower as to be visible at a distance of at least five nautical miles 90 percent of the nights of the year. The lights shall be displayed not less than 20 feet above mean high water, but not at a height greater than that governed by the requirement in § 67.05-1(f) that mariners be able to see at least one of the lights, regardless of the angle of approach, until within 50 feet of the structure, visibility permitting.