The Occupational Safety and Health Standards (OSHA) and American National Standards Institute/National Equipment Manufacturers Association (ANSI/NEMA) Z535 require floor signs. OSHA 29 CFR 1910.145(c)(2 states that caution signs must be used to warn people about the presence of potential hazards. By placing floor signs in strategic locations in your workplace, you can make people aware of the potential hazard there so that they can practice safety.
Based on the ANSI Z535.2-2011 (R2017) Environmental Facility and Safety Signs, you must ensure that hazard-alerting signages are not placed on or adjacent to movable objects like windows, doors, and more.