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No, there are no requirements to color machine guards yellow, orange, or any other color. According to 1910.144(a)(3), yellow shall be the basic color for designating “caution” and for marking physical hazards such as: striking against, stumbling, falling, tripping, and “caught in between.” However, this regulation was not meant to state directly or by implication that all machine guards be painted yellow.
According to the Safety Color Code (ANSI Z535.1-1998), yellow is the basic color for designating caution and for marking physical hazards such as “caught in between.” Also, ANSI Z535.1-1998 designates orange as the color for identifying hazardous machine parts which may crush or otherwise injure, as well as for identifying exposed parts. Orange also is used to indicate “warning.” Note: The later editions of ANSI Z535.1 no longer contain the safety color meanings.
The coloring of machine guarding yellow, orange, or any color is not required but can encourage employees not to remove the guarding unless they are trained and authorized. Lockout/tagout under 1910.147 may be required when maintenance is performed on the gears under the guard.