[Code of Federal Regulations] [Title 47, Volume 1] [Revised as of October 1, 2004] From the U.S. Government Printing Office via GPO Access [CITE: 47CFR17.51] [Page 856] TITLE 47--TELECOMMUNICATION CHAPTER I--FEDERAL COMMUNICATIONS COMMISSION PART 17_CONSTRUCTION, MARKING, AND LIGHTING OF ANTENNA STRUCTURES--Table of Contents Subpart C_Specifications for Obstruction Marking and Lighting of Antenna Structures Sec. 17.51 Time when lights should be exhibited. (a) All red obstruction lighting shall be exhibited from sunset to sunrise unless otherwise specified. (b) All high intensity and medium intensity obstruction lighting shall be exhibited continuously unless otherwise specified. [40 FR 30267, July 18, 1975, as amended at 61 FR 4364, Feb. 6, 1996]