Where opening of a disconnect would create a hazard, I don’t think you could omit the lock. For example, if the switch served lighting indoors or outdoors, operating the switch at night could create a hazard. An open disconnect for a storm-water pump could create a flooding hazard, and may not be evident until an area becomes ‘submersed.’ There are a number of situations where preventing a switch from being operated (opened or closed) at the wrong time could be considered “practical safeguarding of persons and property.”
But then, I wonder if any switch manufacturer provides printed instructions on proper “use” of the dimple?
