[Code of Federal Regulations]
[Title 49, Volume 4]
[Revised as of October 1, 2003]
From the U.S. Government Printing Office via GPO Access
[CITE: 49CFR393.27]

[Page 1102]
 
                        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. 393.27  Wiring specifications.

    (a) Wiring for both low voltage (tension) and high voltage (tension) 
circuits shall be constructed and installed so as to meet design 
requirements. Wiring shall meet or exceed, both mechanically and 
electrically, the following SAE Standards as found in the 1985 edition 
of the SAE Handbook:
    (1) Commercial vehicle engine ignition systems-SAE J557-High Tension 
Ignition Cable.
    (2) Commercial vehicle battery cable-SAE J1127-Jan 80-Battery Cable.
    (3) Other commercial vehicle wiring-SAE J1128-Low Tension Primary 
Cable.
    (b) The source of power and the electrical wiring shall be of such 
size and characteristics as to provide the necessary voltage as the 
design requires to comply with FMVSS 571.108.
    (c) Lamps shall be properly grounded.

    Note: This shall not prohibit the use of the frame or other metal 
parts of a motor vehicle as a return ground system provided truck-
tractor semitrailer/full trailer combinations are electrically 
connected.

[53 FR 49397, Dec. 7, 1988]