California Code, Vehicle Code - VEH § 36610

(a) The limitations as to height of vehicles contained in Chapter 3 (commencing with Section 35250) of Division 15 do not apply to implements of husbandry incidentally operated, transported, towed, or otherwise moved over a highway.

(b) Notwithstanding subdivision (a), when an implement of husbandry is transported or moved over a highway as a load on another vehicle and the load exceeds 14 feet in height, the vehicle and load shall not be operated for a distance in excess of 25 miles from the point of origin of the trip. The operator of the transporting vehicle shall be a farmer or a person regularly employed by a farmer or farm corporation, and the operator transporting the vehicle shall have in his or her immediate possession a writing signed by the farmer or farm corporation agent which states the origin and destination of the trip.