S.C. Code Regs. 38-393.31. Overload protective devices

(a) The current to all low tension circuits shall pass through overload protective devices except that this requirement shall not be applicable to battery to starting motor or battery to generator circuits, ignition and engine control circuits, horn circuits, electrically operated fuel pump circuits, or electric brake circuits. (b) Trucks and truck tractors meeting the definition of a commercial motor vehicle and manufactured after June 30, 1953 shall have protective devices for electrical circuits arranged so that: (1) The headlamp circuit or circuits shall not be affected by a short circuit in any other lighting circuits on the motor vehicle; or (2) The protective device shall be an automatic reset overload circuit breaker if the headlight circuit is protected in common with other circuits.