United States Department of TransportationInterpretation ID: 0784
Sate-Lite Mfg. Co.
6230 Gross Point Road
Niles, IL 60714
Dear Mr. Reagle:
This is in reply to your recent FAX to Pat Boyd of this agency asking for a confirmation of an interpretation of certain reflex reflector requirements of Motor Vehicle Safety Standard No. 108, specifically S5.7.2.1(b) and (c). For your future reference, requests for interpretation should be addressed to the Chief Counsel.
You state that Mr. Boyd informed you that "any retro- reflector would have to be made in intervals of 4 inches" with the 0 degree at the two-inch mark, and that the reflective reading would have to comply with S5.7.2.1(b) or (c). He also informed you that, regardless of whether the segment was 4, 8, or 12 inches in length, the agency will test in 4-inch segments.
This is correct. According to paragraph S5.7.2.2(a) and (b) of Standard No. 108, each reflector shall be installed "with the center of each reflector not more than 100 mm from the center of each adjacent reflector." As 100 mm is approximately 4 inches, this effectively limits the size of a reflector to a maximum length of 4 inches. However, this does not prohibit the mounting of two or three adjacent reflectors in "segments" of 8 or 12 inches, whether separately or in a housing. As Mr. Boyd informed you, each discrete 4- inch segment must comply with paragraph S5.7.2.1(b) or (c).
Paragraphs S5.7.2.1(b) and (c) specify reflectivity values for red and white reflex reflectors respectively "at any light entrance angle between 30 degrees left and 30 degrees right, including an entrance angle of 0 degrees," as well as "any light entrance angle between 45 degrees left and 45 degrees right." Your drawing of a 4-inch reflector correctly depicts the 0 degree light entrance angle at the 2-inch mark, in the center of the reflector. However, SAE Standard J594f, Reflex
Reflectors, January 1977, incorporated by reference in Standard No. 108, requires the measurement of the other light entrance angles also with respect to the center of the reflector, rather than with respect to the ends as pictured in your drawing.
If you have any further questions, you may call Taylor Vinson of this Office (202-366-5263).
Sincerely,
Philip R. Recht Chief Counsel ref:108 d:4/17/95