Interpretation ID: 77-1.38

TYPE: INTERPRETATION-NHTSA

DATE: 03/04/77

FROM: AUTHOR UNAVAILABLE; F. Berndt; NHTSA

TO: Wesbar Corporation

TITLE: FMVSS INTERPRETATION

TEXT: Thank you for your frank letter of January 13, 1977, commenting upon the lack of clarity you feel exists in my letter to you of December 6, 1976, interpreting Motor Vehicle Safety Standard No. 108.

As a lawyer it is obvious to me that the best regulatory practice is to be as specific as possible in establishing requirements and prohibitions. When a regulation itself is unclear, however, its interpretation may necessarily be imprecise. Because the term "optical combination" in S4.4.1 is not defined, my answers were necessarily worded in general terms though with the thought of establishing a general framework of guidance for you. They were not intended to be "a masterpiece of bureaucratic weasel words." My letter meant, in plain English, that where tail lamps and clearance lamps are in a single compartment we don't want one lamp to perform, or to be perceived as performing, the function of the other. It is evident from your letter and others that our previous interpretations of the term "optical combination" have been found to be ambiguous and lacking in the objective criteria that a Federal motor vehicle safety standard must provide. We have reviewed the matter, and now wish to modify our previous interpretation. In our view a lamp is "optically combined" when the same light source (i.e. bulb) and the same lens area fulfill two or more functions (e.g. taillamp and stop lamp, clearance lamp and turn signal lamp). A dual filament bulb would be regarded as the "same light source". In determining conformance, the photometric requirements for clearance and taillamp functions, where two bulbs are located in a single compartment, must be met with only the bulb energized that is designed to perform the specific function. But the 15 candlepower maximum under Standard No. 108, however, would be determined with both the taillamp and clearance lamp bulb energized. Further, the lamp must be located to meet requirements for both clearance and taillamps. Our re-interpretation means that the issue of light spill-over from one area of the lamp to another is irrelevant to conformance.

SINCERELY,

January 13, 1977

Frank Berndt Acting Chief Counsel U.S. Dept. of Transportation National Highway Traffic Safety Administration

Refer: N40-30 Your letter of December 6, 1976

A combination of a Christmas holiday with the family in Arizona and year end activity here in our plant has prevented our sending you a reply to the referenced letter at an earlier date.

As far as we are concerned, your response to our October 28 letter is a masterpiece of bureaucratic weasel words and one which avoids positive answers or defensible positions on the specific questions we submitted.

Discussing first your lengthy second paragraph; from line 6 we quote: ". . . . Standard 108 does not require separate compartments (i.e. and opaque barrier) for tail lamps and clearance lamps . . . " Perhaps you can give some scientific explanation how two lamps can be in the same compartment and not interfere optically with one another. The degree of candlepower emanating from each bulb is dependent on their respective candlepowers and in the case of tail and clearance lamp bulbs, the lumens generated are not very far apart since clearance lamp bulbs deliver 2 c.p. and tail lamp bulbs 3 c.p. If tail lamp and clearance lamp bulbs were positioned relatively close together in the single compartment (a condition you state is permissible) I submit that a "driver in a following vehicle" could not possibly interpret one lamp from the other.

May we refer you to line 15 of the second paragraph of your letter and we quote: "there is no appreciable amount of incidental light emitted from the lens of the clearance lamp . . . " To any engineer or attorney involved with compliance regulations, the words "appreciable amount" are incongruous when applied to a standard such as 108, the purpose of which is to spell out specific optical values, tests, and locations for lights. DOT 108 standard permits no deviation from the SAE standards referenced, which standards positively indicate optical values for lamps. Nor does DOT 108 permit any option on the number and types of lamps required on a trailer or where these lamps shall be located. "Appreciable" has no measureable value, therefore, we ask, whose judgement will prevail when evaluating the design and testing of a lamp, the manufacturer or your compliance people. How would you legally defend your position that a light has an "appreciable" amount of spill, hence is illegal, in the absence of an applicable photometric standard.

We also object to the language: "The amount of light spill appears to be so small . . ." (sce para. 2 line 17). What numerical candlepower value do you assign to the words "appears to" as a measure of whether or not a lamp conforms to the published standard? Would we receive approval from your compliance group on a lamp we have marked "DOT" on the basis of our contention that to us the lamp "appears to" meet the photometric standards?

How evasive can a response to our specific question be than your blanket reply of: "If you apply this general principle to the questions you asked, then I think you will have the answers."

We refer you to page 2, lines 2, 3, and 4 of your letter, which we quote: "The principle is necessarily dependent upon the candlepower output of any lamp to which it is applied, a value not given in your questions." Of course we didn't specify "candlepower output". Those values are specified in DOT 108. Or perhaps you were unaware that clearance lamp bulbs and tail lamp bulbs are manufactured to *SAE J573f which specified: Typical Service Trade No. Mean Spherical Candela M ** 57 2 candlepower at 14 volts T *** 1157 3 candlepower at 14 volts

* Photometric tests performed under SAE J592e and SAE J585d are always made using 2 c.p. and 3 c.p. bulb respectively.

** M - Marker, Clearance, Identification

*** T - Tail

These are the lamps and respective candlepowers you will find in all tail lamps and clearance lamps.

Therefore, with such a small candlepower difference between clearance and tail lamp output, the "spill" (to quote your letter) from one to the other, with bulbs exposed in the same compartment, equate one another.

We read with surprise in your letter that "certification is dependent upon a manufacturer's good faith in attempting to achieve compliance." We would like to believe that statement, but the actual experiences of many trailer manufacturers with your compliance people, doesn't bear out what you say. The compliance man recognizes but one criteria: does it or does it not meet the specific requirements of the published standard.

At this moment in time the DOT is quibbling over a specific interpretation of S 4.4.1 with such indecisive language as: "appears to be", "appreciable amount", "good faith". It could be that your indefinite position merely covers a too hasty interpretation by one of your staff, but whatever the reason, please either resolve this problem in terms of specific numbers, or rewrite S 4.4.1 so that there can be no possible misinterpretation of your requirements.

You asked the writer to comment on combining tail and clearance lamp. This combination for boat trailers and some camping trailers is an extremely sensible approach. The 108 standard blankets big semi trailers and small duck boat trailers with the same sets of rules, which rules for a semi trailer are as totally practical as they are totally impractical for a small boat trailer.

In the matter of boat trailers, the over 80" lighting requirements are almost impossible to meet. For example, consider a boat trailer carrying a sail boat. It is virtually impossible to locate an identification light bar that won't be swept off or severely bent when the boat is launched. Use of an identification light bar on a trailer should be eliminated. Very few are operable after a launching.

The trailer manufacturer certifies his trailer as meeting the DOT standards, when it leaves his plant. The dimensions of the boats that trailer may carry vary wiedely and many a trailer's actual width is exceeded by the hull it carries. This is knowledge the trailer manufacturer would not have when he produced the trailer.

It would be economical as well as practical to permit a boat trailer manufacturer to mount his tail lamp in such a position that it would serve the dual purpose of clearance and tail lamp, with no detriment to safety. If anything, we would consider such an arrangement a safer condition than the use of seperate lights.

In conclusion, would you please give us specific answers to the questions posed in paragraph 6 of letter of October 28, 1976, at your earliest convenience. For your convenience a copy of same is attached.

B. R. Weber Executive Vice President

cc: SEN. WILLIAM PROXMIRE; SEN. GAYLOR NELSON