Interpretation ID: 19837.ztv

[       ]

Dear [     ]:

This is in reply to your letter of March 26, 1999, asking for an interpretation of Federal Motor Vehicle Safety Standard No. 108 as it relates to a new product you are developing. Because the product is new, you have commented that you would appreciate our "discretion and confidentiality."

As Taylor Vinson of this Office explained to you on April 9, 1999, our interpretations are a matter of public record, and lighting devices must be described with sufficient detail for the interpretation to be understandable. However, we can, on request, withhold from copies of the interpretation available to the public any material that identifies the addressee and company. You agreed to this treatment of your letter.

You are about to begin the design of a rear identification lamp system which would be a "light bar" with three identification lamps contained within a single lens/base. The lamps would be spaced on 6 to 8-inch centers. You have asked if this conforms to Standard No. 108 "as long as each individual lamp meets the requirements for an identification lamp and as long as there are three distinct 'hot spots' shining through the single lens."

Identification lamps must meet the requirements of SAE Standard J592e Clearance, Side Marker, and Identification Lamps, July 1972, incorporated by reference in Standard No. 108. Paragraph 2.4 of SAE J592e defines identification lamps as "lamps used in groups of three." This can be interpreted as meaning that the lamps must be separate, individual units. However, we would view this aspect of the identification lamp requirement as met if the light bar were constructed so that the three lamps would be perceived as individual lamps. This does not appear to be the case with your system. We interpret your description as indicating that the entire light bar would be illuminated with the hot spots intended to be discernable from the rest of the light bar. If our understanding is correct, your system would not meet the identification lamp requirement of Standard No. 108. However, if you design the light bar with three chambers behind the single lens so that the assembly when lit has the appearance of three separate lamps with no spillover between the chambers, we would consider that as a design that meets this requirement of Standard No. 108.

You have also asked whether this product can also incorporate "a set of brake lights to act as a 'third eye' brake light, similar to those required for automobiles." In other words, the identification lamp bar would act as a supplementary stop lamp when the brakes are applied.

Standard No. 108 permits supplementary lamps as long as they do not impair the effectiveness of the lighting equipment required by the standard (S5.1.3). The function of the identification lamps is to indicate the presence of a large vehicle in the roadway. This effectiveness of this function would not be impaired by an increase in intensity of the lamps when the brake pedal is applied. Therefore, your product can incorporate a supplementary stop lamp function.

If you have any questions you may call Taylor Vinson (202-366-5263).

Sincerely,
Frank Seales, Jr.
Chief Counsel
ref:108
d.6/23/99