[Code of Federal Regulations] [Title 49, Volume 4] [Revised as of October 1, 2002] From the U.S. Government Printing Office via GPO Access [CITE: 49CFR393.29] [Page 1062] TITLE 49--TRANSPORTATION CHAPTER III--FEDERAL MOTOR CARRIER SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION PART 393--PARTS AND ACCESSORIES NECESSARY FOR SAFE OPERATION--Table of Contents Subpart B--Lighting Devices, Reflectors, and Electrical Equipment Sec. 393.29 Grounds. The battery ground and trailer return ground connections on a grounded system shall be readily accessible. The contact surfaces of electrical connections shall be clean and free of oxide, paint, or other nonconductive coating.