[Code of Federal Regulations] [Title 49, Volume 4] [Revised as of October 1, 2005] From the U.S. Government Printing Office via GPO Access [CITE: 49CFR234.249] [Page 575-576] TITLE 49--TRANSPORTATION CHAPTER II--FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION PART 234_GRADE CROSSING SIGNAL SYSTEM SAFETY--Table of Contents Subpart D_Maintenance, Inspection, and Testing Sec. 234.249 Ground tests. A test for grounds on each energy bus furnishing power to circuits that affect [[Page 576]] the safety of warning system operation shall be made when such energy bus is placed in service and at least once each month thereafter.