Interpretation ID: nht70-1.31

DATE: 01/09/70

FROM: AUTHOR UNAVAILABLE; C. A. Baker; NHTSA

TO: Dr. N. Kinon

TITLE: FMVSS INTERPRETATION

TEXT: Thank you for your letter of November 14, 1969, concerning electrically heated windshields.

At present, we do not have a Federal Motor Vehicle Safety Standard which deals specifically with electrically heated windshields. This does not mean, however, that various states may not have restrictions covering this matter. Standard No. 205 stipulation both visibility and structural performance requirements for glazing surfaces used in automobiles as well as in other vehicles. If the product you manufacture meets the requirements of Standard No. 205, then it is acceptable under our existing regulations.

We assume from previous conversations with Mercedes Benz that this electrically heated windshield would be offered as an optional piece of equipment. We understood that it would be used as a supplement to the standard blower-type defrosting system. If this is actually the case, then the electrically heated windshield would not have to meet the performance requirements of Standard No. 108, but the blower-type unit would have to pass the defrosting test.

We recognize that the automotive industry has shown an increasing interest in using electrically heated glass to defrost windows. At present, several manufacturers offer electrically heated glass in the rear window (backlight) as an optional piece of equipment. Assuming that this product helps defrost glazing surfaces, we recognize that it has a safety potential that should be effectively utilized.

On the other hand, we also recognize that this product could interfere with visibility, depending upon the wire size pattern and location. This is an area which needs further study.