Interpretation ID: nht91-7.49

DATE: December 18, 1991

FROM: Paul Jackson Rice -- Chief Counsel, NHTSA

TO: Masashi Maekawa -- Director, Technical Division, Ichikoh Industries, Ltd.

TITLE: None

ATTACHMT: Attached to letter dated 11-27-91 from Masashi Maekawa to Paul Jackson Rice (OCC 6714)

TEXT:

This responds to your letter of November 27, 1991, asking for an interpretation of Motor Vehicle Safety Standard No. 108 as it relates to a specific vehicle design.

Your letter depicts a combination tail/stop lamp that would be mounted on the deck lid ("Lamp B"), immediately adjacent to a combination tail/stop lamp that is mounted on the vehicle body ("Lamp A"). Each lamp complies with the requirement for effective projected luminous lens area, but neither complies with photometric requirements. You have asked whether, under S5.1.1.6 it is possible to consider the two adjacent lamps as one lamp for purposes of measuring the photometrics for tail and stop lamps, and, if so, whether the requirements for one or two lighted sections will apply.

S5.1.1.6 covers requirements for replacement stop lamps, and does not appear relevant to our question. We have, however, addressed before the question that you raise. It is not possible to consider the two adjacent lamps as one lamp for purposes of measuring the minimum photometrics required under Standard No. 108. We regard the lamp that is located on the body, Lamp A, as the lamp that must be designed to conform to all applicable requirements of Standard No. 108, including photometrics. In that location, Lamp A meets the requirement that stop/taillamps be located as far apart as practicable, whereas Lamp B would not. The requirements that would apply to Lamp A are those for lamps with a single lighted section. Since your letter indicates that Lamp A does not meet photometric requirements, Lamp A would be a nonconforming lamp. Lamp B is permissible as supplementary lighting equipment and need not meet the photometric or location requirements in order for the vehicle to comply with the standard. Thus, Lamp B would be permissible in its present state. (The sole restriction that Standard No. 108 imposes upon supplementary lighting equipment is that it must not impair the effectiveness of required lighting equipment; that possibility does not appear to exist in this design, where the two lamps are intended as complementary).