Rule 4501-25-04 | Lamp requirements.
(A) Warning lamps shall have at least twelve square inches of effective illuminated area.
(1) The exposed illuminated area of the lamp shall have no word, letter, nor other device on the lens intended to identify the signal.
(2) The flashing signal from a double-faced signal lamp shall not be obliterated when subjected to external light rays from either in front or behind, at any and all angles.
(B) Each warning lamp shall be powered by an optical element of not less than twenty-one candlepower with reflectorization sufficient to assure visibility for at least one thousand feet to the front and rear of the vehicle.
Supplemental Information