Mr. Gary L. King
Supervisor of Regulations & Standards
R&D Dept.
North American Lighting, Inc.
26750 Haggerty Road
Farmington Hills, MI 48331

Dear Mr. King:

This is in reply to your letter of April 24, 2000, asking for a clarification of our views on photometric test requirements for multi-compartment rear combination lamps.

You ask whether it is correct to say that a rear combination lamp system (stop lamp, turn signal lamp, taillamp) which consists of lamps on both the rear deck lid and fender which have the appearance of a single lamp with multiple compartments may be considered two lamps because they are not physically connected. If this is the correct interpretation, you then ask for confirmation that the fender-mounted lamp is the lamp that must meet all photometric requirements applicable to stop lamps, taillamps, and rear turn signal lamps.

We confirm your interpretation as it pertains to the rear combination lamp system you describe. Even though a lamp system design may have the appearance of a single lamp with multiple compartments, the system cannot be considered a single lamp when it is mounted both on the deck lid and adjacent fender. It is impossible for the two portions to share a common housing or lens because the housing and lens must be separated in order for the deck lid to open. Thus, the system you describe consists of two lamps. As we have indicated in previous interpretations, we regard the combination lamp that is mounted on the body as the one that must be designed to comply with Standard No. 108. This is because a body-mounted lamp will be visible at all times, whereas one on the deck lid will not be in its design orientation should the deck lid be ajar when the vehicle is in operation, such as may occur when the driver is carrying a load.

You have also referred to the requirement in S5.3.1 of Standard No. 108 that lighting equipment be mounted on a rigid part of the vehicle, and asked whether the deck lid can be considered a "rigid part." Yes, the deck lid is a rigid part. This specification was adopted primarily to forestall installation of rear reflex reflectors on mud flaps. However, consistent with the discussion in the prior paragraph, in terms of your design, we consider the second lamp to be supplemental lighting equipment because all items required by Standard No. 108 must be mounted on the body. This supplemental lamp may be mounted on the deck lid because the complying lamp will remain in its design orientation regardless of the position of the deck lid.

If you have any questions, you may phone Taylor Vinson of this Office (202-366-5263).

Frank Seales, Jr.
Chief Counsel