Interpretation ID: aiam4695
U.S.A. P.O. Box 6555 Cypress
CA 90630;
Dear Mr. Maeda: This is in reply to your letter of September 28, l990 requesting an interpretation of Motor Vehicle Safety Standard No. 108. Table IV of the standard establishes a minimum 'edge to edge separation distance' between turn signal lamps and tail or stop lamps installed on motorcycles. You have asked whether the edge in question is the outer edge of the lamp assembly itself, or the edge of the reflector in the lamp. The minimum edge to edge separation distance is measured from the edge of the illuminated surface of one lamp to another, that is to say, from the edge of the effective projected luminous area of one lens to the edge of the effective projected luminous area of the other. It is unclear from the drawing you enclosed of the 'tail/brake lamp' whether the edge of its effective projected luminous area of the lens is at the edge of the reflector, or at the edge of the lamp (as appears to be the case with the 'turn signal'). If the former, the distance is measured between the edge of the tail/stop lamp reflector to the edge of the turn signal lamp assembly as you have initially indicated. Sincerely, Paul Jackson Rice Chief Counsel;