License plate lamp requirements

From an NTEA member A motor carrier officer issued a warning that our license plate was not properly lighted. What are the requirements? Unlike a typical passenger vehicle, work trucks come in a variety of configurations with numerous locations where a license plate can be installed. Although there is no federal regulation regarding license plate location, many states have some requirements — primarily focused on plate visibility, and maximum and minimum height. Check with your individual state for more information. Requirements for license plate illumination, however, are part of Federal Motor Vehicle Safety Standard (FMVSS) 108: Lamps, Reflective Devices, and Associated Equipment, and Canadian Motor Vehicle Safety Standard (CMVSS) 108. F/CMVSS 108 for a license plate primarily focuses on illumination and photometric testing requirements. For reference, “S6.1.3.3 License plate lamp. The license plate lamp or lamps installed on vehicles other than motorcycles and motor driven cycles must be mounted so as to illuminate the license plate without obstruction from any designed feature unless the lamp or lamps is (are) designed to comply with all the photometric requirements with these obstructions considered.” This section helps with general requirements for license plate illumination. Typically, a license plate is illuminated with either one lamp from the top or two lamps on each side. The lamp system must be installed on a vehicle to provide illumination on all parts of a 6-inch by 12-inch (150 mm by 300 mm) test plate. The test points shown in the image above must register an illumination value of no less than 8 lx {0.75 fc} at each test station target location shown. For a single lamp used to illuminate the license plate, the lamp and license plate holder must bear such relation that at no point on the plate must the incident light make an angle of less than 8 degrees to the plane of the plate (this angle being measured from the edge of the light-emitting surface of the lamp farthest from the surface of the plate). When two or more lamps are used to illuminate the license plate, the minimum 8-degree incident light angle must apply only to that portion of the plate which the particular lamp is designed to illuminate. The test for measuring plate illumination is contained in “S14.2.2.1 Illumination surface. All illumination measurements are made on a rectangular test plate of clean, white blotting paper mounted on the license plate holder in the position normally taken by the license plate. The face of the test plate must be 1/16 of an inch or 1.5 mm from the face of the license plate holder.” While F/CMVSS 108 does not have a lamp height limitation, many states have maximum and minimum height limitations for placement of the license plate itself. A final-stage manufacturer’s decision on number of lamps needed to meet illumination requirements will be based on lamp location and ability to meet the 8-lux requirement. Lighting manufacturers have information that can help you choose the correct lamp for either your single- or two-lamp license plate lighting system.

License plate lamp requirements

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