The "Lockout Mandatory" sign ensures health and safety of employees and individuals in the workplace by establishing the required presence of a locking system to control energy from given machinery, equipment or process. It draws attention to the associated risks with the given action and ensures that the appropriate reaction to given energy emergencies is handled accordingly. 

The sign is best displayed in workplaces with machinery, equipment and certain high energy processes and reactions occur. It should be visible to all employees and individuals in the given space.