Suppose you lock out the controls to a motor. Will this protect you from inadvertent operation of the motor so that you can safely disconnect the leads?
Theoretically, the answer is yes. You can look at the drawing and see this motor won’t run if there’s no power to its control circuit. The problem here is you’re relying on a single safety point. It is also theoretically possible that someone could remove your lock or something else could happen to permit power to