Interpretation ID: aiam2475
Exterior Lighting Development
Chrysler Corporation
P.O. Box 1118
Detroit
MI
48231;
Dear Mr. Weil: This is in reply to your letter of September 16, 1976, to Mr. Brooks o this agency on photometric test requirements of multiple compartment and multiple lamp configurations. You have asked for our concurrence on two interpretations of Standard No. 108, as discussed below.; In your 'example 1', on vehicles designed with a two lamp system parking and (or taillamp) and turn signal functions are combined in each lamp of the two lamp system. You have asked whether the second lamp in this system would be treated as supplemental and need not meet the photometric requirements for required lamps.; The answer is no. As you are aware the photometric requirements o multiple lamps or multiple compartment lamps, where a tail or parking lamp is combined with the turn signal lamp, are partially determined by Note 4 to SAE Standard J588e *Turn Signal Lamps*. Note 4 establishes permissible ratios of intensity between functions *i*. *e*. that the intensity of the tail or parking lamps shall not be so great as to diminish the effectiveness of the turn signal function. Where two lamps are used and the distance between filament centers does not exceed 22 inches (as appears to be the case here) the combination of the lamps must be used to meet the photometric requirements for the corresponding number of lighted sections. (Paragraphs 3.1 of J585d, J588e). Further, the ratio of the turn signal to the tail or parking lamps must be computed with all the lamps lighted (Note 4). With reference to those vehicles designed with a two-lamp system (your example 1), your first answer is the correct one, the lamps would be photometered together to meet the two compartment requirements for the two lamp functions performed, as specified in Table 1 of Standard No. 108.; With respect to your example 2, a multiple compartment lamp with on compartment performing turn signal and parking or tail lamp functions, and the other portion the function of parking or tail lamp only, photometric requirements for the tail lamp function are determined on the basis of the output of the two compartments. The single compartment parking lamp may, however, be treated as a 'supplemental' lamp, except that the candlepower ratios (with turn signal lamp) must be met with both parking lamp compartments illuminated.; Sincerely, Frank A. Berndt, Acting Chief Counsel