Interpretation ID: nht70-1.27

DATE: 10/28/70

FROM: ROGER H. COMPTON -- NHTSA OFFICE OF OPERATING SYSTEMS MOTOR VEHICLE PROGRAMS

TO: E. W. BERNITT -- VICE PRESIDENT SAFETY AND QUALITY ASSURANCE AMERICAN MOTORS CORPORATION JEEP CORPORATION

TITLE: NONE

TEXT: Dear Mr. Bernitt:

This is in reply to your letter of October 12, 1970, to Mr. Charles A. Baker of this office in which you requested an interpretation of the phrase "effective projected illuminated area."

Class A turn signal lamps are required by Section S3.1 of Federal Motor Vehicle Safety Standard No. 108, which references SAE Standard J588d in Tables I and III for these lamps. The requirements for the illuminated area of a turn signal lamp are specified in J588d as follows:

"The effective projected illuminated area measured on a plane at right angles to the axis of the lamp must not be less than 12 sq. in. for Class A and 3 1/2 sq. in. for Class B."

In the 45 degree visibility requirements, this standard further states "To be considered visible, the lamp must provide an unobstructed projected illuminated area of outer lens surface, excluding reflex, . . .".

Our interpretation of effective projected illuminated area follows: The effective projected illuminated area is that area of the lens measured on a plane at right angles to the axis of the lamp, excluding reflex reflector, which is not obstructed by an opaque object such as a mounting screw, mounting ring or an ornamental bezel or trim.

The above interpretation allows the area of rings or other configurations (raised portions) molded in the lens to be considered part of the total effective area, even if this area does not contribute significantly to the total light output.

Sincerely,