8.9.3 Material and Construction
The data plate shall be such material and construction that the letters and figures stamped, etched, cast, or otherwise applied to the face shall remain permanently and readily legible. The height of the letters and figures shall be not less than 3.2 mm (0.125 in.).
All data plates not located in the controller shall be provided with either
(a) a durable means that prevents common contaminants (such as paint, adhesives, oil, and grease) from adhering to the data plate parent surface and permits the removal of these contaminants, without obscuring the Code-required data
(b) letters and figures that are raised or depressed a minimum of 0.8 mm (0.03125 in.) from the plate surface face and have a minimum character-stroke width of 0.5 mm (0.02 in.)
If the plates are exposed to weathering or a chemical atmosphere, then a durable means shall be provided to protect the information from deterioration while permitting the information to be easily read.
Existing Code data plates that comply with the edition of the Code under which they were installed and have legible accurate information do not have to be changed to comply with these material and construction requirements.