Interpretation ID: Evans_10-005739_108

Mark A. Evans, President
Calcoast - ITL
4072 Watts Street
Emeryville, CA 94608

Dear Mr. Evans:

This is in reply to your letter of July 13, 2010, asking for an interpretation of Federal Motor Vehicle Safety Standard (FMVSS) No. 108.

You asked whether in assessing the performance of replaceable bulb headlamps that use high intensity discharge ballasts under the corrosion test the ballast should be included in the corrosion determination. You stated that some manufacturers believe that the ballast can be treated as a separate component because it is replaceable and therefore should not be counted in assessing the headlamps resistance to corrosion.

The performance requirements for the corrosion resistance test found in paragraph S8.4 are set forth in paragraph S7.5(i) and S7.4(h)(3). These paragraphs require that, after a corrosion test of a headlamp conducted according to paragraph S8.4, "there shall be no evidence of external or internal corrosion or rust visible without magnification." Paragraph S8.4(b) states that the headlamp be subjected to the corrosion resistance test unfixtured. Paragraph S4 defines a headlamp test fixture as a test device "whose mounting hardware and components are those necessary to operate the headlamp as installed" on a motor vehicle.

Since the headlamp is to be tested unfixtured, the agency does not equip a headlamp with mounting hardware and associated components at the time of compliance testing for corrosion resistance. All other components of the headlamp, however, are subject to the corrosion test and are required to comply with the corrosion resistance requirements in paragraphs S7.5(i) and S7.4(h)(3) of FMVSS No. 108. Thus, even though the ballast is deemed to be replaceable, the agency includes it in determining whether the lamp has exhibited signs of corrosion.

If you have further questions, you may refer them to Thomas Healy of this Office (202-366-7161).

Sincerely,

O. Kevin Vincent

Chief Counsel

5/24/2011