Interpretation ID: nht75-3.4

DATE: 11/05/75

FROM: AUTHOR UNAVAILABLE; F. Berndt; NHTSA

TO: General Electric Company

TITLE: FMVSS INTERPRETATION

TEXT: This is in reply to your letter of July 8, 1975, to Ed Leysath of this agency concerning wattage requirements for Type 1A and 2A headlamps.

Your specific question is whether the wattage specifications in Federal Motor Vehicle Safety Standard No. 108 for Type 1A and 2A headlamps are design wattages or maximum wattages.

Paragraph S4.1.1.21(b) of Standard No. 108 specifies that, "Each Type 1A headlamp shall be designed for a maximum of 50 watts. Each Type 2A headlamp shall be designed for a maximum of 60 watts for each filament." (Emphasis added.) It follows, therefore, that the 50 - and 60-watt values are design wattages. You are correct in your interpretation that a tolerance of approximately 7.5% applies to these values, and that an ampere value of 4.20 for a 50-watt filament and 5.02 for a 60-watt filament is permitted. The 7.5% tolerance as you know is the average actual maximum wattage (as opposed to design wattage) rating of headlamps listed in Table 2 of SAE Standard J573 as determined by multiplication of the maximum amperage times the design volts.

Sincerely,

ATTACH.

GENERAL ELECTRIC COMPANY

July 8, 1975

Ed Leyseth -- National Highway Traffic Safety Administration, Department of Transportation

Subject: FMVSS 108 - Section 4.1.1.2.1

Dear Mr. Leyseth,

On March 26, 1975 I wrote to Bill Eason and requested an interpretation of the wattage requirements of the rectangular headlamp system. (copy enclosed). To date we have heard nothing and we urgently need your reply.

I would appreciate your help in providing us with your interpretation as quickly as possible.

Very truly yours,

Frank W. Bowers -- Manager, Product Reliability

attach: copy of 3/26/75 letter March 26, 1975

William Eason -- National Highway Safety Administration, Department of Transportation

Subject: FMVSS 108 - Section 4.1.1.21

Dear Mr. Eason:

I have heard that the Department of Transportation has interpreted Section 4.1.1.21(6) of FMVSS as far as the wattage limitation on Type 1A and Type 2A rectangular headlamps is concerned.

It is my understanding that the 50 watt limit on the Type 1A and the 60 watt limit on the 2A apply as design maximums and that a tolerance of approximate 7.5% applies to these values. This, then, would permit a max. ampere value of 4.20 for a 50 watt filament and 5.02 for a 60 watt filament. If a 40 watt filament is used than its max. amperes would be 3.36.

I agree with this interpretation and understand that these are the figures that SAE is proposing.

I would appreciate it very much if you would confirm that this interpretation is correct since design and certification of the product depends upon an accurate interpretation of the standard.

Thanks very much for your help in this matter.

Very truly yours,

F. W. Bowers -- Manager, Product Reliability

bcc: R. G. Burnor #1200