Disconnecting Means for Access Control Power Supply

Question; Do Access Control System Power Supplies that are hard wired, (not cord connected) do they require a disconnecting means with in site of the actual controller and if required must it have the ability to be locked in the on position in order to prevent accidental de-energization by non-authorized persons? My gut tells me its a requirement, my heartburn is I cannot find the code article that dictates the need for a disconnecting means. Help!