Interpretation ID: 21012.ztv

Brandon Billingsley, Vice President Marketing
CRS Electronics
Heavy Duty Bus Parts
17850 I-45
Willis, TX 77318

Dear Mr. Billingsley:

We are replying to your letter of November 19, 1999, with respect to your "new overhead LED warning light system for school buses." You ask whether your product will comply with Federal standards.

You call the new technology "strobing LEDs," and say that you are able to "build a warning light module that combines the 'attention grabbing,' authoritative effect of strobe lights and the long life expectancy of LEDs." You have tested "according to the protocols of SAE J887," and report that your product "does indeed exceed the requirements of SAE J887 for strobe lights."

We assume that you wish to offer your product as original equipment on school buses. The acceptability of your product is determined by Federal Motor Vehicle Safety Standard No. 108, Lamps, Reflective Devices, and Associated Equipment. Paragraph S5.1.4 of Standard No. 108 requires each school bus to be equipped with a system of four red signal (or four red and four amber) lamps designed to conform to SAE Standard J887, July 1964. Under this standard, school bus warning system lamps are required to flash alternately in a range of 60 to 120 flashes a minute. Unlike later versions of J887, an optional flash rate in Hz is not specified.

A few years ago we were asked whether a school bus warning system consisting of strobe lights met Standard No. 108. I enclose a copy of our letter of March 29, 1994, to Harry C. Gough. The system we were asked about was described as flashing "on and off four times in a 255 millisecond period and then stays off for 745 milliseconds, then the lamp on the opposite side of the vehicle repeats the aforementioned pattern." We replied that we believed that the light emanating from a strobe lamp under these performance parameters "will be perceived as a single flash of varying intensity and not as four separate flashes, and that when this is followed by an identical pattern on the other side of the bus, the system is one that is alternatively flashing within the meaning of Standard No. 108."

You did not specify the flash rate of your product, but you may use our 1994 interpretation as a guideline for determining whether the light would be perceived "as a single light of varying intensity," and hence compliant with Standard No. 108. If it would not be so perceived, then your lamps would appear to be noncompliant with the Standard's requirements.

The minimum photometric requirements of the 1964 specification are also the ones that apply to your product. I enclose a copy for your information.

If you have questions, you may call Taylor Vinson of this Office (202-366-5263).

Sincerely,
Frank Seales, Jr.
Chief Counsel
Enclosures
ref:108
d.2/29/2000