Interpretation ID: nht91-4.3

DATE: May 22, 1991

FROM: Paul Jackson Rice -- Chief Counsel, NHTSA

TO: George D. Powley -- Project Engineer, Truck-Lite Co., Inc.

TITLE: None

ATTACHMT: Attached to letter dated 4-29-91 from George D. Powley to Paul Jackson Rice (OCC 6011)

TEXT:

This responds to your letter of April 29, 1991, with respect to the orientation of electrical contact blades on sealed beam headlamps.

Truck-Lite would like to produce both a large rectangular Type 2B1 sealed beam headlamp and a small rectangular Type 2A1 headlamp using the same blade orientation. Specifically, you would like to use the 2B1 orientation on the 2A1 unit. You do not feel that this would affect adversely the lamp's "ability to interchange with existing lamps in motor vehicles presently in the field."

The basic dimensional requirements for sealed beam headlamps are set forth in SAE Standard J1383 APR85 Performance Requirements for Sealed Beam Headlamps, incorporated by reference in Motor Vehicle Safety Standard No. 108. However, in reference to the Figures of J1383 which set forth the dimensions, "only those dimensions marked 'I' for interchangeability are applicable." (Section S7.3 of Standard No. 108). Our examination of the Figures indicate that the electrical contact blade orientation dimensions for Type 2A headlamps are marked "I", and thus must be met by Type 2A headlamps designed to comply with Standard No. 108. On the other hand, the contact blade orientation dimensions for Type 2B headlamps do not appear to be marked "I", and the manufacturer may depart from the ones indicated without violating Standard No. 108.

This means that you could not use a Type 2B1 blade orientation on a Type 2A1 headlamp as you wish. On the other hand, you could use the Type 2A orientation on the Type 2B, if you find it feasible to do so.

You also indicated that Koito is currently selling Type 2A1 headlamp with a non-standard contact blade orientation. I have forward a copy of this letter to our Office of Vehicle Safety Compliance for appropriate action. Thank you for calling this matter to our attention.