Interpretation ID: Maxzone Interpretation EPLLA 571.108_(002) signed

October 4, 2024

VIA EMAIL

Ms. Penny Chiu 

Product Marketing Coordinator 

Maxzone Auto Parts Corp. 

mkt1363@maxzone.com

Dear Ms. Chiu, 

This responds to your email, dated July 7, 2023, seeking a legal interpretation regarding the proper calculation of the “effective projected luminous lens area” (EPLLA) under Federal Motor Safety Standard (FMVSS) No. 108, Lamps, reflective devices, and associated equipment, and the inclusion of a “diffusion element,” as well as the “distinctive water wave pattern” on your product. You also submitted additional information via email to NHTSA staff, such as diagrams of your product and other supporting information, on June 28, 2023, and July 12, 2023, which was taken into consideration in developing this response. 

In responding to this request, NHTSA notes that the contents of this letter do not have the force and effect of law and are not meant to bind the public in any way. This letter is only intended to provide clarity regarding existing requirements under the law at the time of signature. 

Based on the information you have provided and for the reasons explained below, our answer is that the area you describe as the “diffusion element” and the area you describe as having a “distinctive water wave pattern” can be included in the calculation of the EPLLA of your lamp under FMVSS No. 108 only if those elements are not transparent and direct light toward the photometric test pattern. However, based on the information you have provided, we are unable to state whether such elements do or do not perform such a function. 

Background 

NHTSA is authorized by the National Traffic and Motor Vehicle Safety Act (Safety Act, 49 U.S.C. Chapter 301) to issue FMVSS that set performance requirements for new motor vehicles and new items of motor vehicle equipment. NHTSA does not provide approvals of motor vehicles or motor vehicle equipment. Instead, manufacturers are required to self-certify that their products conform to all applicable FMVSSs that are in effect on the date of manufacture before the products can be offered for sale. In so doing, manufacturers must have some independent basis for their certification that a product complies with all applicable safety standards, and they must ensure that the vehicle would comply when tested by NHTSA.1 This requirement does not necessarily mean that a manufacturer must conduct the specific tests set forth in an applicable standard, in this case FMVSS No. 108. Certifications may be based on, among other things, engineering analyses, actual testing, and computer simulations. Whatever the basis for certification, however, the manufacturer must certify that the product complies with a standard as it is written, i.e., that the vehicle will pass all applicable requirements if it is tested exactly according to the standard’s test conditions and other specifications. Manufacturers must also ensure their products are free of safety-related defects. This letter represents NHTSA’s opinion concerning how your product, as you describe it, would be analyzed under FMVSS No. 108. It is not an approval of your product. 

In your July 7, 2023, email, you ask whether the EPLLA of your lamp, as defined in FMVSS No. 108, should include the area you describe as the “diffusion element,” or only the area you describe as the “refractive element.”2 You note that what you describe as the “diffusion element” of your product includes scattering structures as well as a “distinctive water wave pattern,” which you state “serves the purpose of diffusing light” and which you believe contributes to spreading the light emitted from the lamp. Your June 28 email includes two diagrams of the product which you state show the product’s EPLLA3 and the impact of the scattering structures on the surface. Finally, your July 12 email includes an image identifying the elements of your lamp. We note that although your question is regarding your product, which is a turn signal lamp, you have not asked about the EPLLA requirements applicable to a specific type of motor vehicle lamp. Therefore, your question, and this response, may be applicable to multiple lamp types. 

FMVSS No. 108, S6.4.1 states that “[e]ach turn signal lamp, stop lamp, high-mounted stop lamp, and school bus signal lamp must meet the applicable effective projected luminous lens area requirement specified in Tables IV–a, IV–b, and IV–c.” Furthermore, the lens area certification and compliance option in S6.4.3(a) states that “[w]hen a vehicle is equipped with any lamp listed in Table V–b each such lamp must provide not less than 1250 sq mm of unobstructed effective projected luminous lens area in any direction throughout the pattern defined by the corner points specified in Table V–b for each such lamp.” Table V-b includes turn signal lamps, stop lamps, taillamps, and parking lamps. Turn signal lamps certified under the lens area option must provide unobstructed minimum effective projected luminous lens area of 1250 sq mm at a horizontal angle of 45° and a vertical angle of 15°. 

As defined in FMVSS No. 108, EPLLA “means the area of the orthogonal projection of the effective light-emitting surface of a lamp on a plane perpendicular to a defined direction relative to the axis of reference. Unless otherwise specified, the direction is coincident with the axis of reference.”

1 Letter to Helen A. Rychlewski, responding to letter received June 7, 1995, available at https://www.nhtsa.gov/interpretations/aiam5591.
2 Your submission also cites to the definition of “Diffusion Element” in Society of Automotive Engineers standard J2999. This definition is not incorporated into FMVSS No. 108.
3 The image submitted appears to indicate that your calculated EPLLA is 5648.159 sq mm.

FMVSS No. 108 also defines “effective light-emitting surface” as “that portion of a lamp that directs light to the photometric test pattern, and does not include transparent lenses, mounting hole bosses, reflex reflector area, beads or rims that may glow or produce small areas of increased intensity as a result of uncontrolled light from an area of ½° radius around a test point.” 

The definition of “effective light-emitting surface” was added to FMVSS No. 108 in a final rule published on August 11, 2004 (2004 final rule).4 This action amended the standard for turn signal lamps, stop lamps, taillamps, and parking lamps to increase compatibility with the requirements of the Economic Commission for Europe and to improve the visibility of these lamps. In the 2004 final rule, NHTSA responded to comments on the proposed amendments and definitions. In so doing, we noted that “transparent lenses cannot be included in the determination of the effective light-emitting surface.”5 Furthermore, we also stated the following:

“[T]here does not appear to be any substantive change in determining the effective projected luminous lens area. However, the proposed definition clearly stated that only the portion of the lamp that directs light to the photometric test pattern may be included in the determination of the effective light-emitting surface. … we believe that transparent lenses do not direct light to the photometric test pattern and may not be included in the calculation. However, portions of translucent lenses intended to deliberately scatter the beam pattern within the allowable photometry (e.g., frosted or stippled lenses), are permissible as part of the effective projected luminous lens area.”6 

This statement makes clear that EPLLA does include translucent structures that direct light to the photometric test pattern by diffusing or scattering light, even if such structures are on otherwise transparent lenses. 

Discussion 

We now turn to your questions regarding your product. We understand you to be asking two distinct but related questions. First, whether the area that you describe as the “diffusion element” may be included for EPLLA? Second, does the presence of what you describe as the “distinctive water wave pattern” allow an area to be included in the EPLLA? We take these questions in turn. 

Regarding the first question, the definition of effective light-emitting surface makes clear that the area of transparent lenses may not typically be included in the calculation of the effective light

4 69 FR 48805 (Aug. 11, 2004). See also Letter to Dennis Moore, Nov. 15, 2006, at https://www.nhtsa.gov/interpretations/06-003601as.
5 69 FR 48805, 48811 (Aug. 11, 2004). This statement was consistent with a June 14, 2000, letter of interpretation in which we stated that the transparent lens covering a large lamp assembly was not the “outer lens surface” of a turn signal lamp that is part of that assembly for the purposes of calculating its visibility requirements. Letter to Shigeyoshi Aihara, June 14, 2000, at https://www.nhtsa.gov/interpretations/20836ztv.
6 69 FR 48805, 48811 (Aug. 11, 2004).

emitting surface. As explained in the 2004 final rule, such elements do not direct light toward the photometric test pattern. 

However, as we have stated in the past, areas of otherwise transparent lenses that incorporate scattering structures, such as frosted or stippled lenses, as well as certain cuts such as prism or pillow cuts and other similar structures, are not “transparent” for purposes of determining the effective light-emitting surface. Rather, these areas are “translucent” and may be included in the calculation of EPLLA, so long as such elements direct the light to the photometric test pattern. Based on the submitted materials, it appears that the area of the “diffusion element” you describe on the lens on your product has such cuts. If these cuts direct light toward the photometric test pattern, then the area of these cuts may be counted as part of your product’s EPLLA. 

We now turn to your second question regarding the “distinctive water wave pattern.” Similarly, if the “distinctive water wave pattern” has the effect of scattering light and directing the light toward the photometric test pattern, then its area may be included in the calculation of the effective light-emitting surface (and therefore, EPLLA). We note, however, that we are unable to determine whether the wave pattern has such an effect based on the information you have provided. As previously stated, the manufacturer must certify the product as compliant with the applicable standards and must exercise reasonable care in making such a certification. 

I hope this information has been helpful. If you have further questions, please contact Eli Wachtel of my staff at (202) 366-2992. 

Sincerely,
ADAM RAVIV
Adam Raviv Chief Counsel

Dated: 10/4/24
Ref: Standard No. 108